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

Transcript of ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG...

Page 1: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

ELF AERODYNAMIC ANALYSIS

By Resolved Analytics

Page 2: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

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

Page 3: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

Computational Fluid Dynamics Model Results – 20 mph

CD = 0.32

Page 4: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

Computational Fluid Dynamics Model Results – 20 mph

Page 5: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

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

Page 6: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

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

Page 7: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

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

Page 8: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

Body Taper Front to Rear

Baseline

Tapered

Page 9: ELF AERODYNAMIC ANALYSIS By Resolved Analytics. Free Body Diagram Forces on the ELF, FDFD FLFL FGFG F RR F D = ½ ρυ 2 C D A F RR = C RR F G P = Fv F G.

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.