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[fp024f] Rear Fender Study

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Yosuke Yamamoto edited this page May 9, 2021 · 60 revisions

fp024f - Rear Fender Study

Introduction

Since there was room to raise the rear fender deck by 50 mm, I simulated some rear fender models of 50mm higher deck with some aerodynamic devices.

Simulation Models

Model Car Overview

fp024f_cfd_car-overview

Rear Fender Models

List of Rear Fender Models

  • Control ( Recalculated: fp024c - Side Mirror C & Fr Fender Louver C3 )
  • 50mm Higher Deck
  • 50mm Higher Deck + Fairing Fin
  • 50mm Higher Deck + Fairing Box
  • 50mm Higher Deck + Fairing Fin + Upper Fence
  • Control + Radiator Outlet Louvre
  • 50mm Higher Deck + Radiator Outlet Louvre

GIF Animations of the Models

fp024f_cfd-gif_rr-fender-50mm-higher-deck_comparisons

fp024f_cfd-gif_rr-fender-50mm-higher-deck_louvre-comparisons

Still Images of the Each Model

fp024f_cfd-label-small_00_control

fp024f_cfd-label-small_01_rr-fender-50mm-higher-deck

fp024f_cfd-label-small_02_rr-fender-50mm-higher-deck_fairing-fin

fp024f_cfd-label-small_03_rr-fender-50mm-higher-deck_fairing-box

fp024f_cfd-label-small_04_rr-fender-50mm-higher-deck_fairing-fin_upper-fence

fp024f_cfd-label-small_10_control_radiator-louvre

fp024f_cfd-label-small_11_rr-fender-50mm-higher-deck_radiator-louvre

Simulations

SimScale Project URL: https://www.simscale.com/workbench/?pid=6664511854195853653&mi=spec%3A9f1f9ba5-3e8f-4cc6-bf71-eb8d96356531%2Cservice%3ASIMULATION%2Cstrategy%3A11943

Conditions

  • Freestream Velocity Magnitude Value : 30 [m/s]
  • Ride Height : Front / Rear = 110 [mm] / 110 [mm]

Results - Coefficieints

  • NOTE
    • RF: Radiator Flow

fp024f: Control

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0263 0.0013 0.0211 0.0039
Cd 0.5688 0.4574 0.0491 0.0623
Cl -0.1923 -0.2300 0.0304 0.0073
Clf -0.0698 -0.1137 0.0363 0.0076
Clr -0.1225 -0.1163 -0.0059 -0.0003
CoP 0.6369 0.5056 -0.1936 -0.0379
L/D -0.3380 -0.5029 0.6187 0.1179
RF 0.1628 m3/s

fp024f: Rr Fender 50mm Higher Deck

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0258 0.0007 0.0212 0.0039
Cd 0.5684 0.4556 0.0492 0.0636
Cl -0.1941 -0.2326 0.0306 0.0078
Clf -0.0713 -0.1155 0.0365 0.0078
Clr -0.1229 -0.1170 -0.0059 0.0000
CoP 0.6328 0.5031 -0.1925 0.0044
L/D -0.3416 -0.5105 0.6224 0.1227
RF 0.1620 m3/s

fp024f: Rr Fender 50mm Higher Deck - Fairing Fin

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0258 0.0005 0.0212 0.0041
Cd 0.5681 0.4569 0.0492 0.0620
Cl -0.1980 -0.2355 0.0306 0.0069
Clf -0.0732 -0.1173 0.0365 0.0076
Clr -0.1248 -0.1183 -0.0059 -0.0006
CoP 0.6303 0.5022 -0.1930 -0.0916
L/D -0.3486 -0.5156 0.6207 0.1120
RF 0.1620 m3/s

fp024f: Rr Fender 50mm Higher Deck - Fairing Box

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0264 0.0038 0.0212 0.0014
Cd 0.5671 0.4594 0.0493 0.0584
Cl -0.1949 -0.2372 0.0307 0.0117
Clf -0.0710 -0.1148 0.0366 0.0072
Clr -0.1239 -0.1225 -0.0059 0.0045
CoP 0.6356 0.5162 -0.1925 0.3842
L/D -0.3437 -0.5163 0.6225 0.1999
RF 0.1626 m3/s

fp024f: Rr Fender 50mm Higher Deck - Fairing Fin - Upper Fence

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0248 -0.0005 0.0215 0.0039
Cd 0.5691 0.4582 0.0497 0.0613
Cl -0.1958 -0.2342 0.0311 0.0073
Clf -0.0730 -0.1176 0.0371 0.0075
Clr -0.1227 -0.1165 -0.0059 -0.0002
CoP 0.6269 0.4977 -0.1911 -0.0315
L/D -0.3440 -0.5111 0.6265 0.1186
RF 0.1913 m3/s

fp024f: Control - Radiator Louvre

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0278 0.0032 0.0210 0.0036
Cd 0.5662 0.4565 0.0492 0.0605
Cl -0.1839 -0.2219 0.0303 0.0077
Clf -0.0641 -0.1077 0.0362 0.0074
Clr -0.1197 -0.1141 -0.0059 0.0003
CoP 0.6512 0.5144 -0.1945 0.0388
L/D -0.3247 -0.4861 0.6159 0.1276
RF 0.2447 m3/s

fp024f: Rr Fender - 50mm Higher Deck - Radiator Louvre

Coef. Whole Car Body Fr Wheel Rr Wheel
Cm 0.0263 0.0018 0.0212 0.0033
Cd 0.5674 0.4562 0.0492 0.0620
Cl -0.1890 -0.2281 0.0306 0.0086
Clf -0.0682 -0.1123 0.0364 0.0076
Clr -0.1208 -0.1159 -0.0059 0.0010
CoP 0.6391 0.5079 -0.1931 0.1129
L/D -0.3331 -0.5000 0.6205 0.1380
RF 0.2358 m3/s

Comparisons

Comparisons of Coefficients

Comparison of the Whole Body Coefficients

Coef. Control 50mm H-D
Std		 50mm H-D
Fin		 50mm H-D
Box		 50mm H-D
Fin+UprFence		 Control
+ Rad. Louver		 50mm H-D
Std
+ Rad. Louver
Cd 0.5688 0.5684 0.5681 0.5671 0.5691 0.5662 0.5674
Cl -0.1923 -0.1941 -0.1980 -0.1949 -0.1958 -0.1839 -0.1890
Clf -0.0698 -0.0713 -0.0732 -0.0710 -0.0730 -0.0641 -0.0682
Clr -0.1225 -0.1229 -0.1248 -0.1239 -0.1227 -0.1197 -0.1208
CoP 0.6369 0.6328 0.6303 0.6356 0.6269 0.6512 0.6391
L/D -0.3380 -0.3416 -0.3486 -0.3437 -0.3440 -0.3247 -0.3331
RF m3/s 0.1628 0.1620 0.1620 0.1626 0.1913 0.2447 0.2358

Differences from "Original Rear Fender (Control)" - Coefficients

Coef. Control 50mm H-D
Std		 50mm H-D
Fin		 50mm H-D
Box		 50mm H-D
Fin+UprFence		 Control
+ Rad. Louver		 50mm H-D
Std
+ Rad. Louver
∆Cd 0.0000 -0.0004 -0.0007 -0.0017 0.0003 -0.0026 -0.0014
∆Cl 0.0000 -0.0019 -0.0058 -0.0026 -0.0035 0.0084 0.0033
∆Clf 0.0000 -0.0015 -0.0034 -0.0012 -0.0032 0.0057 0.0016
∆Clr 0.0000 -0.0004 -0.0024 -0.0014 -0.0003 0.0027 0.0017
∆CoP 0.0000 -0.0040 -0.0066 -0.0013 -0.0100 0.0143 0.0022
∆L/D 0.0000 -0.0035 -0.0106 -0.0056 -0.0060 0.0133 0.0049
∆RF m3/s 0.0000 -0.0008 -0.0008 -0.0002 0.0285 0.0819 0.0730
fp024f_cfd-graph_rr-fender_coef-diff
  • "Rr Fender 50mm Higher Deck + Fin" increases front and rear downforces best.
  • Front and rear downforce increasements of "Rr Fender 50mm Higher Deck + Box" are around half compared to the "Fin" type.
  • "Rr Fender 50mm Higher Deck + Box" has slight adavntage with drag decreasement compared to the "Fin" type
    • It may be possible to reduce drag by developing "Box" shape.
  • "Rr Fender 50mm Higher Deck + Fin + Upper Fence" spoils the rear downforce improved by "Fin" shape, but it has the effect of increasing the radiator flow which will be described later.
  • Radiator outlet louvres reduce downforce, but "Rr Fender 50mm Higher Deck + Radiator Louvre" reduces the reduction.

Comparison of Raditator Flows and Distributions

Comparison of Radiator Flows

fp024f_cfd-graph_rr-fender_radiator-flow
  • 4 cases: "Control", "Rr Fender 50mm Higher Deck", "Rr Fender 50mm Higher Deck + Fin" and "Rr Fender 50mm Higher Deck + Box" are almost the same.
  • "Rr Fender 50mm Higher Deck + Fin + Upper Fence" has the highest radiator flow rate among the models without louvers, which is about 18% higher.
  • "Rr Fender-50mm Higher Deck + Radiator Louvre" has about 3.6% less radiator flow rate than "Control + Radiator Louvre".
    • But as mentioned above, it has less adverse effect on downforce.

Comparison of Raditator Flow Distributions

fp024f_cfd-gif_radiator-flow_comparison

fp024f_paraview_radiator_control

fp024f_paraview_radiator_50mm-higher-deck

fp024f_paraview_radiator_50mm-higher-deck_fairing-fin

fp024f_paraview_radiator_50mm-higher-deck_fairing-box

fp024f_paraview_radiator_50mm-higher-deck_fairing-fin_upper-fance

fp024f_paraview_radiator_control_louvre

fp024f_paraview_radiator_50mm-higher-deck_louvre

Comparisons of Floor Pressure

Animation PNG of the all cases

fp024f_cfd-apng_floor-pressure_comparison

Animation PNG of comparisons with/without Radiator Louvre

fp024f_cfd-apng_floor-pressure_comparison_control-louver

fp024f_cfd-apng_floor-pressure_comparison_50mm-higher-deck-louver

  • The radiator outlet louvres seem to reduce downforce by reducing the low pressure on the underside of the floor.

Animation PNG of comparison between Rr Fender "Control" and "50mm Higher Deck" with Radiator Louvre

fp024f_cfd-apng_floor-pressure_comparison_control-50mm-higher-deck-louver

  • Comparing the 2 models with radiator louvers, "50mm Higher Deck" seems to have a slightly stronger low pressure on the underside of the floor.

Summary

  • The "50mm Higher Deck" models generally tend to have better aerodynamic performance than the "Control" model.
  • The "50mm Higher Deck" model reduces the drop in aerodynamic performance when a radiator outlet louver is installed.
  • Among the "50mm Higher Deck" models,
    • "Fin" type increases downforce both front and rear best,
    • "Box" type has a potential for low drag shapes,
    • "Upper Fence" spoils the increase in "Fin" type rear downforce, but increases the radiator flow.
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