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[fp024d] Windscreens

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Yosuke Yamamoto edited this page Feb 12, 2019 · 111 revisions

fp024d - Windscreens

Introduction

A windscreen is installed in a formula car for the following purposes.

  • Reducing the wind flow hitting the driver's head
  • Reducing the influence of turbulent flow which the cockpit opening generates

In this study, several characteristic shapes of windscreens ware simulated and compared to know fundamental characteristics of windscreens.

Models

Model Car Overview

fp-024d_cfd_car-model_overview

Windscreen Models

fp-024d_cfd_windscreens

Original Windscreen - Height 40mm

  • Height 40mm








No Windscreen











Height 40mm - Low at Center

  • Height 40mm
  • Low at Center (0mm)








Height 80mm

  • Height 80mm








Height 80mm - Low at Center

  • Height 80mm
  • Low at Center (0mm)









Simulations

SimScale Project: https://www.simscale.com/workbench/?pid=4379859629083448095&mi=spec%3A7ff5efa4-88d1-4330-a7f0-8d62f6e30e4a%2Cservice%3ASIMULATION%2Cstrategy%3A91

Conditions

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

Results - Coefficients

Original Windscreen (Height 40mm)

Coef. Whole Car Body & Head Body Head Fr Wheel Rr Wheel
Cd 0.5679 0.4565 0.4718 -0.0153 0.0491 0.0624
Cl -0.1925 -0.2303 -0.2465 0.0162 0.0306 0.0072
Clf -0.0688 -0.1128 -0.1155 0.0026 0.0365 0.0076
Clr -0.1237 -0.1175 -0.1310 0.0136 -0.0059 -0.0004
CoP 0.6428 0.5101 0.5316 0.8380 -0.1923 -0.0525
L/D -0.3389 -0.5046 -0.5225 -1.0553 0.6230 0.1162

No Windscreen

Coef. Whole Car Body & Head Body Head Fr Wheel Rr Wheel
Cd 0.6224 0.5131 0.5038 0.0093 0.0483 0.0610
Cl -0.1901 -0.2289 -0.2490 0.0200 0.0306 0.0082
Clf -0.0544 -0.0983 -0.1098 0.0114 0.0364 0.0075
Clr -0.1357 -0.1306 -0.1392 0.0086 -0.0058 0.0007
CoP 0.7136 0.5706 0.5592 0.4289 -0.1892 0.0909
L/D -0.3054 -0.4461 -0.4941 2.1524 0.6342 0.1348

Height 40mm - Low at Center

Coef. Whole Car Body & Head Body Head Fr Wheel Rr Wheel
Cd 0.5786 0.4678 0.4713 -0.0035 0.0488 0.0620
Cl -0.1882 -0.2257 -0.2413 0.0155 0.0303 0.0072
Clf -0.0673 -0.1111 -0.1168 0.0057 0.0362 0.0076
Clr -0.1209 -0.1147 -0.1244 0.0098 -0.0058 -0.0004
CoP 0.6423 0.5079 0.5158 0.6298 -0.1928 -0.0491
L/D -0.3252 -0.4826 -0.5119 -4.4327 0.6217 0.1166

Height 80mm

Coef. Whole Car Body & Head Body Head Fr Wheel Rr Wheel
Cd 0.5703 0.4586 0.4721 -0.0135 0.0491 0.0627
Cl -0.1860 -0.2226 -0.2370 0.0144 0.0299 0.0067
Clf -0.0679 -0.1113 -0.1137 0.0023 0.0358 0.0077
Clr -0.1181 -0.1113 -0.1234 0.0121 -0.0059 -0.0010
CoP 0.6351 0.4999 0.5205 0.8392 -0.1965 -0.1419
L/D -0.3262 -0.4855 -0.5021 -1.0636 0.6098 0.1070

Height 80mm - Low at Center

Coef. Whole Car Body & Head Body Head Fr Wheel Rr Wheel
Cd 0.5692 0.4571 0.4738 -0.0167 0.0492 0.0629
Cl -0.1935 -0.2303 -0.2400 0.0098 0.0303 0.0065
Clf -0.0635 -0.1074 -0.1068 -0.0006 0.0362 0.0077
Clr -0.1300 -0.1229 -0.1333 0.0103 -0.0059 -0.0012
CoP 0.6718 0.5337 0.5551 1.0605 -0.1946 -0.1816
L/D -0.3399 -0.5038 -0.5066 -0.5833 0.6158 0.1034

Comparisons

Coefficient Comparisons

Whole Body

Coef. Height 40mm Original No Windscreen Height 80mm Height 40mm - Low Center Height 80mm - Low Center
Cd 0.5679 0.6224 0.5703 0.5786 0.5692
Cl -0.1925 -0.1901 -0.1860 -0.1882 -0.1935
Clf -0.0688 -0.0544 -0.0679 -0.0673 -0.0635
Clr -0.1237 -0.1357 -0.1181 -0.1209 -0.1300
CoP 0.6428 0.7136 0.6351 0.6423 0.6718
L/D -0.3389 -0.3054 -0.3262 -0.3252 -0.3399

Differences from the Original Windscreen (Height 40mm)

Coef. Height 40mm Original No Windscreen Height 80mm Height 40mm - Low Center Height 80mm - Low Center
∆Cd 0.0000 0.0545 0.0024 0.0107 0.0013
∆Cl 0.0000 0.0024 0.0065 0.0043 -0.0010
∆Clf 0.0000 0.0143 0.0009 0.0014 0.0052
∆Clr 0.0000 -0.0119 0.0056 0.0029 -0.0062
∆CoP 0.0000 0.0708 -0.0077 -0.0006 0.0289
∆L/D 0.0000 0.0335 0.0128 0.0137 -0.0010

fp024d_cfd_coef-diff_whole-car

  • "No Windscreen" generates drag signifcantly and decreases the rear downforce.
  • Compared to "Original Windscreen", Cl, Cd and L/D of "Height 80 mm - Low Center" is about the same. But, Clf decreases, Clr increases, and the downforce distribution becomes rearward nearly 3%.

Cd Comparison of Each Part

Windscreen Type Whole Car Body Head Fr Wheel Rr Wheel
Origin (Height 40mm) 0.5679 0.4718 -0.0153 0.0491 0.0624
No Windscreen 0.6224 0.5038 0.0093 0.0483 0.0610
Height 80mm 0.5703 0.4721 -0.0135 0.0491 0.0627
Height 40mm - Low Center 0.5786 0.4713 -0.0035 0.0488 0.0620
Height 80mm - Low Center 0.5692 0.4738 -0.0167 0.0492 0.0629

Cd Differences from the Original Windscreen (Height 40mm)

Windscreen Type Whole Car Body Head Fr Wheel Rr Wheel
Origin (Height 40mm) 0.0000 0.0000 0.0000 0.0000 0.0000
No Windscreen 0.0545 0.0320 0.0247 -0.0008 -0.0014
Height 80mm 0.0024 0.0003 0.0018 0.0000 0.0003
Height 40mm - Low Center 0.0107 -0.0005 0.0118 -0.0003 -0.0004
Height 80mm - Low Center 0.0013 0.0020 -0.0014 0.0001 0.0005

fp024d_cfd_cd-diff

  • For "Origin (Height 40mm)", "Height 80mm" and "Height 80mm - Low Center", forward forces (opposite to drag) work on the head.

Cl Comparison of Each Part

Windscreen Type Whole Car Clf Clr Body Head Fr Wheel Rr Wheel
Origin (Height 40mm) -0.1925 -0.0688 -0.1237 -0.2465 0.0162 0.0306 0.0072
No Windscreen -0.1901 -0.0544 -0.1357 -0.2490 0.0200 0.0306 0.0082
Height 80mm -0.1860 -0.0679 -0.1181 -0.2370 0.0144 0.0299 0.0067
Height 40mm - Low Center -0.1882 -0.0673 -0.1209 -0.2413 0.0155 0.0303 0.0072
Height 80mm - Low Center -0.1935 -0.0635 -0.1300 -0.2400 0.0098 0.0303 0.0065

Cl Differences from the Original Windscreen (Height 40mm)

Windscreen Type Whole Car Clf Clr Body Head Fr Wheel Rr Wheel
Origin (Height 40mm) 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
No Windscreen 0.0024 0.0143 -0.0119 -0.0025 0.0039 0.0000 0.0010
Height 80mm 0.0065 0.0009 0.0056 0.0095 -0.0018 -0.0006 -0.0005
Height 40mm - Low Center 0.0043 0.0014 0.0029 0.0052 -0.0007 -0.0002 0.0000
Height 80mm - Low Center -0.0010 0.0052 -0.0062 0.0065 -0.0064 -0.0003 -0.0007

fp024d_cfd_cl-diff

  • Lift works on the head in these simulations.

Streamline Comparisons

Streamline Comparison - Front View Animation

fp024d_cfd_windscreen_streamlines-comparison_org-all

  • Windscreens with a height of 80[mm] seem to increase the flow to sideways besides raising upwards.

Streamline Comparison - Left View Animation

fp024d_cfd_windscreen_streamlines-comparison_left_all

Flow Vector and Pressure around the Head - Comparison Animaiton

fp024d_cfd_head_flow-pressure

  • In "No Windscreen" the flow from the upper side of the monocoque strikes the head almost directly.

Summary

  • "No Windscreen" generates drag signifcantly and decreases the rear downforce.
  • Compared to "Original Windscreen", Cl, Cd and L/D of "Height 80 mm - Low Center" is about the same. But, Clf decreases, Clr increases, and the downforce distribution becomes rearward nearly 3%.
  • For "Origin (Height 40mm)", "Height 80mm" and "Height 80mm - Low Center", forward forces (opposite to drag) work on the head.
  • Lift works on the head in these simulations.
  • The "Original Windscreen (Height 40mm)" is the best of these windscreens.
  • If you want to increase the rear downforce, "Height 80mm - Low Center" is the best of these windscreens.
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