research article enhancement of impinging jet...

Research ArticleEnhancement of Impinging Jet Heat Transfer Using Two ParallelConfining Plates Mounted near Rectangular Nozzle Exit

Yoshiaki Haneda1 Akiko Souma1 Hideo Kurasawa1 Shouichiro Iio2 and Toshihiko Ikeda2

1 Nagano National College of Technology Nagano 381-8550 Japan2 Shinshu University Nagano 380-8553 Japan

Correspondence should be addressed to Yoshiaki Haneda hanedanagano-nctacjp

Received 1 October 2013 Accepted 16 January 2014 Published 25 March 2014

Academic Editor Toshiyuki Gotoh

Copyright copy 2014 Yoshiaki Haneda et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Impinging jet heat transfer on a target plate was enhanced by using two parallel confining plates mounted between a rectangularnozzle end plate and a jet target plate The target plate was set equal to 2 3 4 and 5 times the jet exit width ℎ and the gap ratio oftwo parallel confining plates119882ℎ were changed from 27 to 80 only by impinging length119867 = 5ℎ and from 27 to 67 by119867 = 5ℎTwo confining parallel platesmounted near the jet exit produced swing-type flow under some conditions As a result themaximumNusselt number attained around the stagnation point was augmented by about 50 compared to the one for normal impinging jetwithout the two parallel plates and then spatial mean Nusselt number was increased by about 40

1 Introduction

Impinging jets have been used in several industrial processesfor example for cooling of steel glass electronic componentsand gas turbine vanes for drying of paper film and textilesand for freezing food and tissue in cryosurgery because thehigh heat and mass transfer coefficients can be obtainedaround a jet stagnation region and the heat transfer charac-teristics can be easily controlled In the meantime Deo et al[1] have examined characteristics of turbulent jets issuingfrom rectangular nozzles with and without two parallel platesattached as sidewalls to the slotrsquos short sides They reportedthat the potential core of the jet without sidewalls wasshorter than that with sidewalls and the centerline turbulenceintensity of the jet with sidewalls became asymptotical closerto the nozzle exit than that of the jet without sidewalls Theresults suggest that a characteristic of impinging jet heattransfer on a target plate with sidewalls is different from thatwithout sidewalls

By theway jets often impinge onto a target bodymountedin confined spaces for manufacturing processes of frozenfood and heat treatment of electronic components and so

forth San et al [2] and Lin et al [3] have studied heat transferon a surface for mounting an end plate flush with a jet exitGao and Ewing [4] have examined static and fluctuatingwall pressure and heat transfer on a surface for unconfinedjets and confined jets with an end plate They found thatthe location of the decrease in the heat transfer and thefluctuating wall pressure in the confined jets shifted laterallyoutward as a nozzle-to-plate distance increased Fitzgeraldand Garimella [5] have studied characteristics of the flowfield of an axisymmetric confined and submerged turbulentjet impinging normally on a flat plate experimentally Theymapped the toroidal recirculation pattern in the outflowregion characteristic of confined jets with an end plateFenot et al [6] have showed the independence of heattransfer coefficients and effectiveness from a jet injectiontemperature for confined and unconfined jets The resultsshowed that the influence of confinement was weak but ithad a great impact on effectiveness More recently San andShiao [7] have examined the effects of jet plate size andplate spacing for mounting removable bars between an endplate mounted flush with a jet exit and a target plate on theheat transfer characteristics for a confined circular air jet

Hindawi Publishing CorporationJournal of FluidsVolume 2014 Article ID 873684 11 pageshttpdxdoiorg1011552014873684

2 Journal of Fluids

End plateHoneycombWire mesh

Cooler Blower

Static pressure hole

Inverter

1000

Wire mesh

200

300

Flowmeter

Targ

et p

late

Confining plate

100

80

100 100 Sound absorption material

Noise absorbing duct

(a)

W

H

z

xy

Confining plate

Target plate

End plate

hX

Y

200Z

(b)

Figure 1 Schematic illustrations of experimental setup and the coordinate systems

vertically impinging on a flat plate They showed the effectsof the jet plate width-to-jet diameter ratio on the stagnationNusselt number In addition San et al [8] have also studiedimpingement heat transfer of staggered arrays of air jetsconfined with an end plate and the removable bars

Yet up to date there have been few investigations con-cerning heat transfer of a rectangular impinging jet confinedwith an end plate target plate and two confining platesmounted in parallel with long sides of the rectangular nozzleexitThe objective of this work is to examine the flowfield andheat transfer influenced by two parallel plates mounted neara rectangular nozzle exit Measurements of the heat transferand fluctuating pressure on a target plate were performedfor the impinging jet with nozzle-to-target plate distancesand with confining plate-to-plate distances Flow field for theimpinging jet was qualitatively visualized using a smoke-wiremethod and smoke method The experimental facilities usedin this study are presented in the next section The resultsof experiments are then presented and discussed Finally theconclusions obtained here are presented

2 Experimental Apparatus and Procedure

Figure 1 shows schematic illustration of experimental setupand the coordinate system The facility used to produce ajet consisted of a blower a cooler for maintaining the airtemperature within 2∘C of an ambient temperature an orificeflow meter pipes made from polyvinyl chloride some noiseabsorbing ducts and a contraction A honeycomb of length80mm with hexagon cells of 4mm and wire meshes wereinstalled in the connection part of the ducts for rectificationThe nozzle contraction had an area ratio of about 133 1 andemploys a smooth contraction profile based on sine curveand following the curve had parallel section with the lengthof 10mm connecting to the exit to enhance flow uniformityA rectangular nozzle exit contracted had a cross-section area

with the length of 200mm and the width ℎ of 15mm whoseoutlet rimwas arranged flushmountwith an end plateThe jetissuing horizontally through the exit impinged onto a targetplate perpendicularly mounted in the middle plane of thejet The nozzle-to-target plate spacing 119867 was set equal to119867ℎ = 2 3 4 and 5 where those places corresponded to apotential core region of the free jet used in the present studyTwo parallel confining plates having the length of 200mmwhose length andwidth were equal to the length of the nozzleexit and the 119867 value respectively were mounted betweenthe end plate and the target plate for each position 119867 Thespacing between the two confining plates mounted in parallelwith the long sides of the exit 119882 was set equal to 119882ℎ =27 33 4 53 and 67 for 119867ℎ = 2 3 and 4 and to 27 334 53 67 and 8 for 119867ℎ = 5 only The intersection betweenthe geometric jet central axis and a target plate was defined asthe origin of coordinate and the 119911 axis was taken across thelength of the jet exit from the origin

For the measurements of pressure and heat transfer onthe target plate the jet exit velocity obtained from flow ratedivided by the cross-section area of the nozzle exit was setat 10ms resulting in a Reynolds number Re based on thenozzle width ℎ and kinematic viscosity ] of about 9500For only flow visualization using a smoke-wire method thevelocity was set at 5ms to obtain good quality pictures ofthe flow field The adjustment of the flow rate was carriedout by changing the rotational frequency of the blower withan inverter The flow rate was almost constant without theadjustment of its rotational frequency in all cases even if theconfining plate-to-plate spacing and the nozzle exit-to-targetplate distance changed

The target plate for the measurements of fluctuatingpressure on the surface consisted of three pieces as shownin Figure 2 The middle sliding plate was manually traversedalong the 119911 direction within the region minus8 le 119911ℎ le 8 A smallpressure hole with 05mm in diameter and 5mm in depth

Journal of Fluids 3

240

15

B

A

A

Stoppered plate

Sliding plate z direction

A-A section400340

(a)

15

5

B detailed illustration

empty05

Pressure transducer

(b)

Figure 2 Target plate used in the pressure measurement

was drilled from the front surface at its geometrical centerand a differential pressure transducer used in measurementof the pressure was screwed into a blind hole drilled intothe wall to the small hole The transducer output signalwas amplified using a strain amplifier module The voltagesignals from the amplifier were recorded onto a data loggerin 30000 data points at a frequency of 5000Hz Timeaveraged mean pressure and root mean square values of thefluctuating pressure were calculated from the data recordedwith a personal computer The pressure on the target platewas measured at 5mm interval by traversing the sliding platewithin the region minus8 le 119911ℎ le 8

The smoke wire method was used for the visualizationof confined flow field The smoke wire was consisted oftwo nichrome wires with 50 120583m in diameter which wereuniformly twisted together It was individually placed at thecenter of the nozzle exit and a little downstream along the 119910axis It was coated by paraffin oil before each test and heatedby impulse direct current Pictures of the resultant whitestreak lines were taken using digital camera and stroboscopelight Additional flow visualization was conducted oil mistgenerated froma smoke generatorwas absorbed to the blowerand the oil mist gushed out of the nozzle was observed witha video camera

For the measurements of local heat transfer three stain-less steel strips 20120583m thick 8mm wide and 260mm longwere glued in parallel with each other along the 119911-directionThese strips were electrically connected in series and wereheated by passing alternating electric current Distributionof the heated surface temperature was measured with 49thermocouples allocated to contact with the back surface ofthe central strip at 5mm interval so as to cover the regionfrom 119911ℎ = minus8 to 119911ℎ = 8 Heat fluxwas basically uniformbutcorrection was carried out for its nonuniformity produced bythe conductive loss toward the back surface of the target plateon which glass wool with 20mm in thickness was mountedThe radiative heat loss to the ambient was neglected as theradiative heat loss was evaluated to be less than 3 of the total

heat fluxThus LocalNusselt number to be used hereafterwasevaluated by the following equation

Nu =119902netℎ

120582 (119879119908minus 119879119900) (1)

where 120582 is the fluid thermal conductivity 119879119908is the local heat

transfer surface temperature 119879119900is the jet temperature and

119902net is the corrected heat flux and evaluated as follows

119902net =119876

119878minus 119902119888

119902119888=120582119901(119879119908minus 119879119887)

120575

(2)

where 119876 is the total electric power input 119878 the total areaof the heated strips 120575 the thickness of the target plate120582119901the thermal conductivity of the target plate and 119879

119887the

back surface temperature of the target plate measured withadditional 13 thermocouples attached to the back surface ofthe target plate itself and evaluated from the temperaturemeasured with the 13 thermocouples

In this experiment the uncertainty associated with the jetexit velocity and local Nusselt number was estimated to be47 and 78 with a 95 confidence level respectively

3 Result and Discussion

Preliminary experiment for a free jet issuing from therectangular exit was performed The jet velocity for the freejet was measured over the jet central axial range from theexit to 20ℎ with a hot-wire anemometer Figure 3 shows thedistributions of centerline mean velocity presented by119880

119898119880119900

and of root mean square value 1199061015840 of fluctuating velocitynormalized by 119880

119898versus 119883ℎ The results of the previous

rectangular jet with aspect ratio 15 (Alnahhal and Panidis[9]) and of the two-dimensional jet (Bradbury [10]) werealso shown in Figure 3 to compare them with present results

4 Journal of Fluids

0004

001

01

115

05 1 10 40

PresentPresent

Alnahhal (AR15)Bradbury

Xh

UmU

ou998400 Um

Closed parks UmUoOpen parks u998400Um

Slope (minus12)

Figure 3 Distributions of normalized centerline mean velocity andturbulence intensity

The jet potential core region where the values of 119880119898119880119900are

equal with approximately one is 119883ℎ le 5 The normalizedcenterline velocity 119880

119898119880119900 in the region of 119883ℎ ge 7 decays

almost proportional to minus one-half power of 119883ℎ thatis the jet typically have characteristics of a two-dimensionaljet On the other hand the normalized turbulence intensity1199061015840

119880119898 near the jet exit is about 048 and their values in

119883ℎ ge 9 became approximately 02 that value is almost thesame as the result of a two-dimension jet [10]

Normalized mean streamwise velocity119880119880119898 and turbu-

lence intensity 1199061015840119880119898 along the lateral (119884) and spanwise (119885)

directions against 2119884119887119910(119887119910is the distance where the mean

streamwise velocity is half of the centerline velocity at theeach 119883ℎ location) and 119885ℎ are presented in Figures 4(a)-4(b) respectively Solid line in Figure 4(a) is the distributionobtained byGoertlerrsquos solution for a two-dimensional jetThemean velocity and turbulence intensity shown in Figure 4(a)are approximately uniform over the region 2119884119887

119910le |06|

at 119883ℎ = 1 In contrast the uniform regions of the meanvelocity decrease at 119883ℎ = 3 5 and the normalized turbu-lence intensity 1199061015840119880

119898 becomes the saddleback distribution

and the 1199061015840119880119898value increases with increase of 119883ℎ value

The mean velocity along 119885 axis was almost uniform over theregion minus6 le 119885ℎ le 6 even at119883ℎ = 5 in Figure 4(b)

31 Flow Field Characteristics The mean and fluctuatingpressure on the target plate was measured to consider theflow field near its surface and the characteristics of theimpingement heat transfer and the association with thefluctuating pressure Figures 5(a)ndash5(d) show the distributionsof time averaged pressure along 119911 axis for119867ℎ = 2 3 4 and5 The 119875 is the time averaged gauge pressure measured onthe target plate and the 119875

119900119898is time averaged gauge pressure

measured on the target plate at 119911ℎ = 0 for normal impingingjet without the two confining platesThe open both sides areaamong the nozzle end plate confining plates and plate is lessthan or equal to the nozzle exit area only for 119882ℎ = 2733 and 119867ℎ = 2 The 119875 values measured in the region

Uo = 10ms

UU

mu998400 Um

0

05

1

0 1 2 3minus3 minus2 minus1

2Yby

Goertler

Closed marks UUm

Open marks u998400Um

135

135

Xh

(a) Along the 119884axis

UUm

Uo = 10ms

UU

mu998400 Um

0

05

1

0 2 4 6 8 10Zh

u998400Um

minus10 minus8 minus6 minus4 minus2

135

135

Xh

(b) Along the 119885axis

Figure 4Distributions of normalizedmean velocity and turbulenceintensity at different downstream locations

minus6 lt 119911ℎ lt 6 in all cases for 119867ℎ = 2 and 3 and two casesfor 119867ℎ = 4 and 5 with the two confining plates howeverare larger than that for the normal impinging jet The shapeof the pressure distribution with the two confining plates isprobably rather convex for the top around 119911ℎ = 0 or flatin the region minus6 lt 119911ℎ lt 6 for 119867ℎ = 2 3 and 4 Incontrast for 119867ℎ = 5 not all the 119875 values measured forthe presence of the two confining plates are larger than thatfor the normal impinging jet and the shape of the pressuredistribution is concave for the top around 119911ℎ = 0 for119882ℎ =53 The concave shape may be due to presence of a pair ofrecirculation regions around the 119911ℎ = 0 The mean pressuredistributions for all cases are approximately symmetrical for119911 = 0Therefore it is thought that there are not the asymmetrycharacteristics of the flow on the 119911 axis

Figures 6(a)ndash6(d) show the distributions of the fluctu-ating pressure on the target plate for 119867ℎ = 2 3 4 and 5The 1199011015840 shown in Figure 6 is the root mean square value offluctuating pressure The 1199011015840 values increase in most casesowing to mounting the two confining plates The 1199011015840 valuesfor each location of119867ℎ vary with the119882ℎ value

Journal of Fluids 5

0

1

2

3

27334

5367

Wh

0 2 4 6 8zh

minus8 minus6 minus4 minus2

PP

omHh = 2

Normal impinging jet

(a) 119867ℎ = 2

0 2 4 6 8zh

27334

5367

Wh


1

2


Hh = 3

PP

om

(b) 119867ℎ = 3

27334

5367

Wh

0 2 4 6 8zh


1

2

PP

om

Hh = 4


(c) 119867ℎ = 4

0

1

2

27334

53678

Wh

0 2 4 6 8zh


PP

om

Hh = 5


(d) 119867ℎ = 5

Figure 5 Distribution of time averaged pressure on the target plate with confining plates

Table 1 Difference in flow patterns by several conditions

119867ℎ = 2 119867ℎ = 3 119867ℎ = 4 119867ℎ = 5

119882ℎ = 27 (b) (a) (a) (a)119882ℎ = 33 (b) (a) (a) (a)119882ℎ = 4 (b) (b) (b) (a)119882ℎ = 53 (b) (b) (b) (b)119882ℎ = 67 (b) (b) (b) (b)119882ℎ = 8 (b)

Therefore the relation between fluctuating pressure at119911ℎ = 0 and the confining plate-to-plate spacing ratio isshown in Figure 7 The 1199011015840

119900119900

and 1199011015840119900

are the root mean squarevalue of fluctuating pressure on the target plate at 119911ℎ =0 without and with the two confining plates respectivelyThe 119882ℎ positions of the maximum 1199011015840

119900119900

1199011015840

119900

value exist ateach nozzle-to-target plate spacing119867ℎ and those positionsincrease with an increase in the119867ℎ value

The flow fields of the impinging jet without or withthe two confining plates were qualitatively examined bymeans of smoke wire visualization Figures 8(a)ndash8(d) showthe instantaneous photographs taken from side view for theabsence of the two confining plates with 119867ℎ = 2 3 4and 5 respectively The vortices of the jet generated nearthe long side of the exit were approximately symmetric

for the center axis of the jet In addition in the case ofeach impinging distance the jet issued out approximatelyhorizontally

Figures 9(a)-9(b) exemplify the instantaneous pho-tographs taken from side view for presence of the twoconfining plates with 119867ℎ = 3 for 119882ℎ = 33 and 4respectively In the case of 119882ℎ = 33 the direction ofthe flow changed into the upper part and flowed toward thebottom after the flow impinged in the upper confining plateand a recirculation was formed in the bottom of the regionsurrounded with the plates In contrast the flow swung upand down for the jet center surface for119882ℎ = 4

Even in the case of other conditions we can classify it intotwo flow patterns such as Figure 10The flow pattern (a) is thetype that the flow is inclined to either upper part or bottom

6 Journal of Fluids

0

01

02

03

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 2


(a) 119867ℎ = 2

0

01

02

03

04

05

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 3


(b) 119867ℎ = 3

0

01

02

03

04

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 4


(c) 119867ℎ = 4

0

01

02

03

04

27334

53678

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 5


(d) 119867ℎ = 5

Figure 6 Distribution of fluctuating pressure on the target plate with confining plates

1

2

3

4

5

6

7

8

2 3 4 5 6 7 8

23

45

Hh

Wh

p998400 op

998400 oo

Figure 7 Relation between fluctuating pressure and the confiningplate-to-plate distance ratio

and the pattern (b) is the type that the jet flow swings upand downThe presence of the two confining plates mountednear the exit generated the perturbational flow field like

that for using a two-dimensional suddenly expanded nozzle[11] The differences in the flow patterns by the experimentconditions are shown in Table 1 Signs (a) and (b) in Table 1show two kinds of flow patterns shown in Figure 10The clearmechanisms to become two kinds of the flow patterns arenot clear however the conditions are guessed as follows Inthe cases of 119882 lt 119867 the jet is drawn to a either side ofconfining plate due to the Coanda effect because of smallergap between the jet and the confining plates Disruption ofpressure balance between the upper and lower region of thejet for some reason might cause the jet incline to oppositeside In these cases it seems that the vibration of the flow alongspanwise also occurs locally

32 Heat Transfer Characteristics Figure 11 shows the distri-butions of local Nusselt number on the target plate along 119911axis for normal impinging jet without confining plates For119867ℎ = 2 3 and 4 corresponded to a potential core region ofthe free jet used in the present study the Nu values over therange minus6 le 119911ℎ le 6 are closely the same The Nu values for119867ℎ = 5 corresponded to a transition region of the free jetare almost the same as values in the case of 119867ℎ = 2 3 and4 For all the cases the maximum Nu values obtained near

Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5

Figure 8 Photographs taken from side view without confining plates

119911ℎ = plusmn67 resulted from that turbulent intensity measuredalong the 119911 axis in the preliminary study for the free jet hadbeen maximum near the short sides of the exit By the waythe Nu values at the geometric stagnation point were largeabout 11 compared with the results reported by Gardonand Akfirat [12] This discrepancy may have resulted in thedifference in the turbulence intensity near the exit and inthe development process of the turbulence along the jet axisreported by them

Figures 12(a)ndash12(d) show local Nusselt number Nu mea-sured along the 119911 axis for the presence of the two confiningplates at 119867ℎ = 2 3 4 and 5 The solid lines shown inthe figures are the Nu values for the normal impinging jetshown in Figure 11 As the impinging jet flow passed throughboth open sides for the presence of the two confining platesdisappearance of the maximum Nu recognized near 119911ℎ =plusmn67 for the normal impinging jet brought almost uniformityof the Nu values over the whole region on the target plateexcept some conditions The Nu value over the range minus6 le119911ℎ le 6 for the presence of the two confining plates is largerthan Nu value for normal impinging jet

Figure 13 shows the relation between the enhancementratios of the Nu values obtained at the geometric stagnationpoint and 119882ℎ values Nu

119900119900and Nu

119900are the mean values

measured two or three times at 119911ℎ = 0 for the normalimpinging jet and local Nusselt number at 119911ℎ = 0 for thepresence of the two confining plates respectively Maximumenhancement ratio of local Nusselt number achieved hereis about 50 for 119867ℎ = 3 and 4 The enhancement oflocal Nusselt number obtained here probably results fromthe swing-type flow shown in Figure 10 The difference inheat transfer enhancement ratio seems to depend on thedifference in the oscillation frequency of the swing-typeflow when we take the visualization result of the flow intoconsideration Haneda et al [13 14] Fu et al [15ndash17] Lin etal [18] and Chaniotis et al [19] have reported impinging jetheat transfer enhanced owing to oscillating flow The 119882ℎvalues that obtainedmaxima of Nu

119900Nu119900119900for each119867ℎ value

are different from the 119882ℎ values that obtained maxima of1199011015840

119900119900

1199011015840

119900

Narayanan et al [20] andGao andEwing [4] have alsoreported that peak fluctuating wall pressure disagreed with

8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4

Figure 9 Photographs taken from side view for119867ℎ = 3 with confining plates

Nozzleexit

Confining plate

Targ

et p

late

(a) Inclined-type flow

Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow

Figure 10 Flow patterns obtained by the all experimental conditions

Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh



Figure 11 Distribution of local Nusselt number for the normal impinging jet

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5

Figure 12 Distribution of local Nusselt number for presence of confining plates

the peak in an impinging jet heat transfer except stagnationregion

Finally the enhancement of spatial meanNusselt numberaveraged over the region minus8 le 119911ℎ le 8 is shown inFigure 14 Nu

119898119900and Nu

119898are the arithmetic mean value of

the spatial mean Nusselt number calculated from Nu values

measured two or three times for normal impinging jet andthe spatial mean Nusselt number for the presence of thetwo confining plates respectively The spatial mean Nusseltnumber is enhanced by installing the two confining platesin all cases The maximum enhancement of mean Nusseltnumber increased by about 40 for119882ℎ = 53 and 119867ℎ =

10 Journal of Fluids

1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh

Figure 13 Enhancement of local Nusselt number at 119885ℎ = 0

2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o

Figure 14 Enhancement of spatial mean Nusselt number (minus8 le119911ℎ le 8)

4 Thus the presence of the two confining plates mountednear the exit is effective to improve the spatial mean Nusseltnumber as well as local Nusselt number

4 Conclusion

The aim of this study is to investigate the effect of theconfining plates mounted in parallel with long sides of arectangular nozzle on the flow field and impinging jet heattransfer Mean and fluctuating pressure and heat transferon a target plate were measured for several kinds of spac-ing between two confining plates at each impinging platedistance and the flow field was visualized with a smokewire method and a smoke method Time averaged pressureand fluctuating pressure on the surface of the target platevaried with the spacing between the two confining platesand became large owing to the presence of the two confiningplates

The result of flow visualization showed two kinds offlow patterns one was a declined flow type and anotherwas a swing-type flow for the presence of the two confining

plates This complicated flow enhanced the heat transfer onthe target plate and brought almost uniform local Nusseltnumber over the whole region on the target plate Theenhancement ratio of local Nusselt number and spatial meanNusselt number for the presence of the two confining platesare about 50 and 40 respectively

Nomenclature

119887119910 Jet half-velocity width along lateral

coordinate (mm)119867 Distance between nozzle end plate and

target plate (mm)ℎ Jet nozzle width (mm)Nu Local Nusselt number on the target plateNu119898 Spatial mean Nusselt number of Nu withconfining plates

Nu119898119900 Arithmetic mean value of spatial meanNusselt number of Nu

Nu119900 Local Nusselt number at the origin with

confining platesNu119900119900 Arithmetic mean value at the originwithout confining plates

119875 Time averaged gauge pressure on thesurface of target plate (Pa)

119875119900119898 Time averaged gauge pressure on the

surface of target plate at the origin withoutconfining plates (Pa)

1198751015840 RMS value of fluctuating pressure on the

surface of target plate (Pa)1199011015840

o RMS value of fluctuating pressure on thesurface of target plate at the origin withconfining plates (Pa)

1199011015840

119900119900

RMS value of fluctuating pressure on thesurface of target plate at the origin withoutconfining plates (Pa)

119876 Total electric power (W)119902119888 Conductive heat loss per unit area toward

the back surface of target plate (Wm2)119902net Corrected heat flux (Wm2)Re Reynolds number based on the jet exit

velocity ℎ and ]119878 Area of heated strip (m2)119879119887 Temperature on the rear surface of target

plate (K)119879119908 Temperature on the surface of heated strip

(K)119880 Jet mean streamwise velocity (ms)119880119898 Jet mean streamwise velocity on119883 axis

(ms)119880119900 Exit mean centerline velocity (ms)1199061015840 RMS value of velocity fluctuation (ms)119882 Distance between confining plates (mm)119883 Axial coordinate from the center of jet exit

(mm)

Journal of Fluids 11

119909 Axial coordinate from geometricalstagnation point on target plate (mm)

119884 Lateral coordinate for free jet (mm)119910 Lateral coordinate on the target plate

(mm)119885 Spanwise coordinate for free jet (mm)119911 Spanwise coordinate on the target plate

(mm)120575 Thickness of target plate (mm)120582 Thermal conductivity of air (WmK)120582119901 Thermal conductivity of target plate(WmK)

] Kinematic viscosity of air (m2s)

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] R C Deo G J Nathan and JMi ldquoComparison of turbulent jetsissuing from rectangular nozzles with and without sidewallsrdquoExperimental Thermal and Fluid Science vol 32 no 2 pp 596ndash606 2007

[2] J San C Huang and M Shu ldquoImpingement cooling of aconfined circular air jetrdquo International Journal of Heat andMassTransfer vol 40 no 6 pp 1355ndash1364 1997

[3] ZH Lin Y J Chou andYHHung ldquoHeat transfer behaviors ofa confined slot jet impingementrdquo International Journal of Heatand Mass Transfer vol 40 no 5 pp 1095ndash1107 1997

[4] NGao andD Ewing ldquoInvestigation of the effect of confinementon the heat transfer to round impinging jets exiting a long piperdquoInternational Journal of Heat and Fluid Flow vol 27 no 1 pp33ndash41 2006

[5] J A Fitzgerald and S V Garimella ldquoA study of the flow field ofa confined and submerged impinging jetrdquo International Journalof Heat and Mass Transfer vol 41 no 8-9 pp 1025ndash1034 1998

[6] M Fenot J-J Vullierme and E Dorignac ldquoLocal heat transferdue to several configurations of circular air jets impinging ona flat plate with and without semi-confinementrdquo InternationalJournal of Thermal Sciences vol 44 no 7 pp 665ndash675 2005

[7] J San and W Shiao ldquoEffects of jet plate size and plate spacingon the stagnation Nusselt number for a confined circular air jetimpinging on a flat surfacerdquo International Journal of Heat andMass Transfer vol 49 no 19-20 pp 3477ndash3486 2006

[8] J San Y Tsou and Z Chen ldquoImpingement heat transfer ofstaggered arrays of air jets confined in a channelrdquo InternationalJournal of Heat and Mass Transfer vol 50 no 19-20 pp 3718ndash3727 2007

[9] M Alnahhal and T Panidis ldquoThe effect of sidewalls on rectan-gular jetsrdquo Experimental Thermal and Fluid Science vol 33 no5 pp 838ndash851 2009

[10] L J S Bradbury ldquoThe structure of a self-preserving turbulentplane jetrdquo Journal of Fluid Mechanics vol 23 part 1 pp 31ndash641965

[11] S Goppert T Gurtler HMocikat andH Herwig ldquoHeat trans-fer under a precessing jet effects of unsteady jet impingementrdquoInternational Journal of Heat and Mass Transfer vol 47 no 12-13 pp 2795ndash2806 2004

[12] R Gardon and J C Akfirat ldquoHeat transfer characteristics ofimpinging two-dimensional air jetrdquo ASME Journal of HeatTransfer vol 88 pp 101ndash108 1966

[13] Y Haneda Y Tsuchiya K Nakabe and K Suzuki ldquoEnhance-ment of impinging jet heat transfer by making use of mechano-fluid interactive flow oscillationrdquo International Journal of Heatand Fluid Flow vol 19 no 2 pp 115ndash124 1998

[14] Y Haneda Y Tsuchiya H Kurasawa K Nakabe and K SuzukildquoFlow field and heat transfer of a two-dimensional impingingjet disturbed by an elastically suspended circular cylinderrdquoHeatTransfermdashAsian Research vol 30 no 4 pp 313ndash330 2001

[15] W Fu K Wang and W Ke ldquoAn investigation of block movingback and forth on a heat plate under a slot jetrdquo InternationalJournal of Heat andMass Transfer vol 44 no 14 pp 2621ndash26312001

[16] W-S Fu and K-N Wang ldquoAn investigation of a block movingback and forth on a heat plate under a slot jet Part II (the effectsof block moving distance and vacant distance)rdquo InternationalJournal of Heat and Mass Transfer vol 44 no 24 pp 4649ndash4665 2001

[17] W Fu C Tseng C Huang and K Wang ldquoAn experimentalinvestigation of a block moving back and forth on a heat plateunder a slot jetrdquo International Journal ofHeat andMass Transfervol 50 no 15-16 pp 3224ndash3233 2007

[18] Y Lin M Hsu and C Hsieh ldquoEnhancement of the convectiveheat transfer for a reciprocating impinging jet flowrdquo Interna-tional Communications in Heat and Mass Transfer vol 30 no6 pp 825ndash834 2003

[19] A K Chaniotis D Poulikakos andY Ventikos ldquoDual pulsatingor steady slot jet cooling of a constant heat flux surfacerdquo ASMEJournal of Heat Transfer vol 125 no 4 pp 575ndash586 2003

[20] VNarayanan J Seyed-Yagoobi andRH Page ldquoAn experimen-tal study of fluid mechanics and heat transfer in an impingingslot jet flowrdquo International Journal of Heat and Mass Transfervol 47 no 8-9 pp 1827ndash1845 2004

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


FluidsJournal of

Atomic and Molecular Physics

Journal of



Advances in Condensed Matter Physics

OpticsInternational Journal of



AstronomyAdvances in

International Journal of


Superconductivity


Statistical MechanicsInternational Journal of


GravityJournal of


AstrophysicsJournal of


Physics Research International


Solid State PhysicsJournal of

Computational Methods in Physics

Journal of



Soft MatterJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


Journal of

Biophysics


ThermodynamicsJournal of

2 Journal of Fluids

End plateHoneycombWire mesh

Cooler Blower

Static pressure hole

Inverter

1000

Wire mesh

200

300

Flowmeter

Targ

et p

late

Confining plate

100

80

100 100 Sound absorption material

Noise absorbing duct

(a)

W

H

z

xy

Confining plate

Target plate

End plate

hX

Y

200Z

(b)

Figure 1 Schematic illustrations of experimental setup and the coordinate systems

vertically impinging on a flat plate They showed the effectsof the jet plate width-to-jet diameter ratio on the stagnationNusselt number In addition San et al [8] have also studiedimpingement heat transfer of staggered arrays of air jetsconfined with an end plate and the removable bars

Yet up to date there have been few investigations con-cerning heat transfer of a rectangular impinging jet confinedwith an end plate target plate and two confining platesmounted in parallel with long sides of the rectangular nozzleexitThe objective of this work is to examine the flowfield andheat transfer influenced by two parallel plates mounted neara rectangular nozzle exit Measurements of the heat transferand fluctuating pressure on a target plate were performedfor the impinging jet with nozzle-to-target plate distancesand with confining plate-to-plate distances Flow field for theimpinging jet was qualitatively visualized using a smoke-wiremethod and smoke method The experimental facilities usedin this study are presented in the next section The resultsof experiments are then presented and discussed Finally theconclusions obtained here are presented

2 Experimental Apparatus and Procedure

Figure 1 shows schematic illustration of experimental setupand the coordinate system The facility used to produce ajet consisted of a blower a cooler for maintaining the airtemperature within 2∘C of an ambient temperature an orificeflow meter pipes made from polyvinyl chloride some noiseabsorbing ducts and a contraction A honeycomb of length80mm with hexagon cells of 4mm and wire meshes wereinstalled in the connection part of the ducts for rectificationThe nozzle contraction had an area ratio of about 133 1 andemploys a smooth contraction profile based on sine curveand following the curve had parallel section with the lengthof 10mm connecting to the exit to enhance flow uniformityA rectangular nozzle exit contracted had a cross-section area

with the length of 200mm and the width ℎ of 15mm whoseoutlet rimwas arranged flushmountwith an end plateThe jetissuing horizontally through the exit impinged onto a targetplate perpendicularly mounted in the middle plane of thejet The nozzle-to-target plate spacing 119867 was set equal to119867ℎ = 2 3 4 and 5 where those places corresponded to apotential core region of the free jet used in the present studyTwo parallel confining plates having the length of 200mmwhose length andwidth were equal to the length of the nozzleexit and the 119867 value respectively were mounted betweenthe end plate and the target plate for each position 119867 Thespacing between the two confining plates mounted in parallelwith the long sides of the exit 119882 was set equal to 119882ℎ =27 33 4 53 and 67 for 119867ℎ = 2 3 and 4 and to 27 334 53 67 and 8 for 119867ℎ = 5 only The intersection betweenthe geometric jet central axis and a target plate was defined asthe origin of coordinate and the 119911 axis was taken across thelength of the jet exit from the origin

For the measurements of pressure and heat transfer onthe target plate the jet exit velocity obtained from flow ratedivided by the cross-section area of the nozzle exit was setat 10ms resulting in a Reynolds number Re based on thenozzle width ℎ and kinematic viscosity ] of about 9500For only flow visualization using a smoke-wire method thevelocity was set at 5ms to obtain good quality pictures ofthe flow field The adjustment of the flow rate was carriedout by changing the rotational frequency of the blower withan inverter The flow rate was almost constant without theadjustment of its rotational frequency in all cases even if theconfining plate-to-plate spacing and the nozzle exit-to-targetplate distance changed

The target plate for the measurements of fluctuatingpressure on the surface consisted of three pieces as shownin Figure 2 The middle sliding plate was manually traversedalong the 119911 direction within the region minus8 le 119911ℎ le 8 A smallpressure hole with 05mm in diameter and 5mm in depth

Journal of Fluids 3

240

15

B

A

A

Stoppered plate


A-A section400340

(a)

15

5


empty05

Pressure transducer

(b)






Nu =119902netℎ

120582 (119879119908minus 119879119900) (1)




119902net =119876

119878minus 119902119888

119902119888=120582119901(119879119908minus 119879119887)

120575

(2)


119887the





119898119880119900




4 Journal of Fluids

0004

001

01

115

05 1 10 40

PresentPresent


Xh

UmU

ou998400 Um


Slope (minus12)












119910le |06|








Uo = 10ms

UU

mu998400 Um

0

05

1


2Yby

Goertler

Closed marks UUm


135

135

Xh


UUm

Uo = 10ms

UU

mu998400 Um

0

05

1

0 2 4 6 8 10Zh

u998400Um


135

135

Xh





Journal of Fluids 5

0

1

2

3

27334

5367

Wh

0 2 4 6 8zh


PP

omHh = 2


(a) 119867ℎ = 2

0 2 4 6 8zh

27334

5367

Wh


1

2


Hh = 3

PP

om

(b) 119867ℎ = 3

27334

5367

Wh

0 2 4 6 8zh


1

2

PP

om

Hh = 4


(c) 119867ℎ = 4

0

1

2

27334

53678

Wh

0 2 4 6 8zh


PP

om

Hh = 5


(d) 119867ℎ = 5



119867ℎ = 2 119867ℎ = 3 119867ℎ = 4 119867ℎ = 5



119900119900

and 1199011015840119900


119900119900

1199011015840

119900






6 Journal of Fluids

0

01

02

03

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 2


(a) 119867ℎ = 2

0

01

02

03

04

05

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 3


(b) 119867ℎ = 3

0

01

02

03

04

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 4


(c) 119867ℎ = 4

0

01

02

03

04

27334

53678

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 5


(d) 119867ℎ = 5


1

2

3

4

5

6

7

8

2 3 4 5 6 7 8

23

45

Hh

Wh

p998400 op

998400 oo





Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5





119900119900and Nu





119900119900

1199011015840

119900


8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Journal of Fluids 3

240

15

B

A

A

Stoppered plate


A-A section400340

(a)

15

5


empty05

Pressure transducer

(b)






Nu =119902netℎ

120582 (119879119908minus 119879119900) (1)




119902net =119876

119878minus 119902119888

119902119888=120582119901(119879119908minus 119879119887)

120575

(2)


119887the





119898119880119900




4 Journal of Fluids

0004

001

01

115

05 1 10 40

PresentPresent


Xh

UmU

ou998400 Um


Slope (minus12)












119910le |06|








Uo = 10ms

UU

mu998400 Um

0

05

1


2Yby

Goertler

Closed marks UUm


135

135

Xh


UUm

Uo = 10ms

UU

mu998400 Um

0

05

1

0 2 4 6 8 10Zh

u998400Um


135

135

Xh





Journal of Fluids 5

0

1

2

3

27334

5367

Wh

0 2 4 6 8zh


PP

omHh = 2


(a) 119867ℎ = 2

0 2 4 6 8zh

27334

5367

Wh


1

2


Hh = 3

PP

om

(b) 119867ℎ = 3

27334

5367

Wh

0 2 4 6 8zh


1

2

PP

om

Hh = 4


(c) 119867ℎ = 4

0

1

2

27334

53678

Wh

0 2 4 6 8zh


PP

om

Hh = 5


(d) 119867ℎ = 5



119867ℎ = 2 119867ℎ = 3 119867ℎ = 4 119867ℎ = 5



119900119900

and 1199011015840119900


119900119900

1199011015840

119900






6 Journal of Fluids

0

01

02

03

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 2


(a) 119867ℎ = 2

0

01

02

03

04

05

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 3


(b) 119867ℎ = 3

0

01

02

03

04

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 4


(c) 119867ℎ = 4

0

01

02

03

04

27334

53678

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 5


(d) 119867ℎ = 5


1

2

3

4

5

6

7

8

2 3 4 5 6 7 8

23

45

Hh

Wh

p998400 op

998400 oo





Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5





119900119900and Nu





119900119900

1199011015840

119900


8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



4 Journal of Fluids

0004

001

01

115

05 1 10 40

PresentPresent


Xh

UmU

ou998400 Um


Slope (minus12)












119910le |06|








Uo = 10ms

UU

mu998400 Um

0

05

1


2Yby

Goertler

Closed marks UUm


135

135

Xh


UUm

Uo = 10ms

UU

mu998400 Um

0

05

1

0 2 4 6 8 10Zh

u998400Um


135

135

Xh





Journal of Fluids 5

0

1

2

3

27334

5367

Wh

0 2 4 6 8zh


PP

omHh = 2


(a) 119867ℎ = 2

0 2 4 6 8zh

27334

5367

Wh


1

2


Hh = 3

PP

om

(b) 119867ℎ = 3

27334

5367

Wh

0 2 4 6 8zh


1

2

PP

om

Hh = 4


(c) 119867ℎ = 4

0

1

2

27334

53678

Wh

0 2 4 6 8zh


PP

om

Hh = 5


(d) 119867ℎ = 5



119867ℎ = 2 119867ℎ = 3 119867ℎ = 4 119867ℎ = 5



119900119900

and 1199011015840119900


119900119900

1199011015840

119900






6 Journal of Fluids

0

01

02

03

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 2


(a) 119867ℎ = 2

0

01

02

03

04

05

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 3


(b) 119867ℎ = 3

0

01

02

03

04

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 4


(c) 119867ℎ = 4

0

01

02

03

04

27334

53678

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 5


(d) 119867ℎ = 5


1

2

3

4

5

6

7

8

2 3 4 5 6 7 8

23

45

Hh

Wh

p998400 op

998400 oo





Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5





119900119900and Nu





119900119900

1199011015840

119900


8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Journal of Fluids 5

0

1

2

3

27334

5367

Wh

0 2 4 6 8zh


PP

omHh = 2


(a) 119867ℎ = 2

0 2 4 6 8zh

27334

5367

Wh


1

2


Hh = 3

PP

om

(b) 119867ℎ = 3

27334

5367

Wh

0 2 4 6 8zh


1

2

PP

om

Hh = 4


(c) 119867ℎ = 4

0

1

2

27334

53678

Wh

0 2 4 6 8zh


PP

om

Hh = 5


(d) 119867ℎ = 5



119867ℎ = 2 119867ℎ = 3 119867ℎ = 4 119867ℎ = 5



119900119900

and 1199011015840119900


119900119900

1199011015840

119900






6 Journal of Fluids

0

01

02

03

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 2


(a) 119867ℎ = 2

0

01

02

03

04

05

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 3


(b) 119867ℎ = 3

0

01

02

03

04

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 4


(c) 119867ℎ = 4

0

01

02

03

04

27334

53678

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 5


(d) 119867ℎ = 5


1

2

3

4

5

6

7

8

2 3 4 5 6 7 8

23

45

Hh

Wh

p998400 op

998400 oo





Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5





119900119900and Nu





119900119900

1199011015840

119900


8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



6 Journal of Fluids

0

01

02

03

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 2


(a) 119867ℎ = 2

0

01

02

03

04

05

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 3


(b) 119867ℎ = 3

0

01

02

03

04

27334

5367

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 4


(c) 119867ℎ = 4

0

01

02

03

04

27334

53678

Wh

0 2 4 6 8zh


p998400 Pom

Hh = 5


(d) 119867ℎ = 5


1

2

3

4

5

6

7

8

2 3 4 5 6 7 8

23

45

Hh

Wh

p998400 op

998400 oo





Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5





119900119900and Nu





119900119900

1199011015840

119900


8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Journal of Fluids 7

End

plat

e

Targ

et p

late

Nozzle exit

(a) 119867ℎ = 2

End

plat

e

Targ

et p

late

Nozzle exit

(b) 119867ℎ = 3

End

plat

e

Targ

et p

late

Nozzle exit

(c) 119867ℎ = 4

End

plat

e

Targ

et p

late

Nozzle exit

(d) 119867ℎ = 5





119900119900and Nu





119900119900

1199011015840

119900


8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



8 Journal of Fluids

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

Confining plate

Confining plate

exit

End

plat

e

Smoke wire method

Targ

et p

late

Confining plate

Confining plate

Nozzle exit

End

plat

e

Smoke method

(a) 119882ℎ = 33Ta

rget

pla

te

Nozzle exit

Confining plate

Smoke wire method

Confining plate

Targ

et p

late

Nozzle exit

Confining plate

Confining plate

Smoke method

End

plat

e

End

plat

e

(b) 119882ℎ = 4


Nozzleexit

Confining plate

Targ

et p

late


Nozzleexit

Confining plate

Targ

et p

late

(b) Swing-type flow


Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Journal of Fluids 9

40

50

60

70

80

23

4

5

HhN

u

0 2 4 6 8zh




40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 2

(a) 119867ℎ = 2

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 3

(b) 119867ℎ = 3

40

50

60

70

80


Nu

0 2 4 6 8zh


27334

5367

Wh

Hh = 4

(c) 119867ℎ = 4

40

50

60

70

80


Nu

0 2 4 6 8zh


8

27334

5367

Wh

Hh = 5

(d) 119867ℎ = 5




119898119900and Nu





1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




1

11

12

13

14

15

16

2 3 4 5 6 7 8Wh

Nu o

Nu o

o

23

45

Hh


2 3 4 5 6 7 8

23

45

Hh

Wh

1

11

12

13

14

15

Nu m

Nu m

o



4 Conclusion




Nomenclature













1199011015840

119900119900








(mm)









References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics











References


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



research article enhancement of impinging jet...

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