elf aerodynamic analysis by resolved analytics. free body diagram forces on the elf, fdfd flfl fgfg...
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ELF AERODYNAMIC ANALYSIS
By Resolved Analytics
Free Body Diagram
Forces on the ELF,
FD
FL
FG
FRR
FD = ½ ρυ2CDAFRR = CRRFG
P = Fv
FG = 500 lbs - FL
CD = ???CRR = 0.005A = 1.39 m2
FM
Computational Fluid Dynamics Model Results – 20 mph
CD = 0.32
Computational Fluid Dynamics Model Results – 20 mph
Addition of Floor
Addition of floor improved Cd by ~ 3.5% Created an “up-wash” effect in rear of vehicle
by keeping flow attached under the vehicle
Addition of Doors/Windows
Sides completely closed in Model results show increase in Cd and more
recirculation along side walls vs. interior of vehicle
Baseline
With Doors
Body Taper Front to Rear
~3 degree taper angle from front to rear Slight Decrease in Frontal Area due to
geometry of cut Model results show Increase in Cd and less
interior recirculation than baseline
Tapered Panel Front ViewTapered Panel Top Plan View
Body Taper Front to Rear
Baseline
Tapered
Body Taper Front to Rear
BaselineTapered
Plan View, Cut Just Along Upper Wheel Well.Baseline Has More Narrow Wake (slightly). Flow Struggles to “Hug” Side Panel of Tapered Vehicle behind Wheel Wells. Tapered Vehicle Has Same “Blockage” Due to Wheel Wells.