Fp024a - Sidepod / Radiator Study


#1

I created a new simulation project called 'fp-024a - Sidepod / Radiator':

Simulation Control Data forked from fp-023d


More of my public projects can be found here.


#2

fp024a - Sidepod / Radiator Study



This study is based on simulations as below.

Contents

  • Simulations
    • Model with Updates
    • Radiator Models
    • Sidepod C / Radiator Duct C
    • Sidepod Radiator Outlet Louvers
    • Radiator Duct D
    • Radiator Duct Turning Vanes
  • Summary

#3

Simulations

Model with Updates

I rebuilt a CFD model with mechanical design updates.
The bodyworks are basically the same with the former model in fp-023d simulation.
Major changes are as follows.

  • Opening holes for suspension arms on the rear bodywork
  • Opening one upper hole on the rear bodywork end
  • Applying designs of mechanical parts inside the bodywork
  • Modifying suspension geometries and arm designs


Coefficients of Forces on Body and Wheels

Coef. Control Model with Updates Difference Difference % Remarks
Cm 0.0518 0.0352 -0.0166 -32.1
Cd 0.5649 0.5637 -0.0013 -0.2
Cl -0.2135 -0.1795 0.0340 -15.9
Clf -0.0550 -0.0546 0.0004 -0.7
Clr -0.1586 -0.1249 0.0336 -21.2
CoP 0.7425 0.6959 -0.0466 -4.7
L/D -0.3780 -0.3185 0.0595 -15.7

Coefficients of Forces on Body Only (without Wheels)

Coef. Control Model with Updates Difference Difference % Remarks
Cm 0.0282 0.0099 -0.0184 -65.1
Cd 0.4531 0.4545 0.0014 0.3
Cl -0.2557 -0.2176 0.0381 -14.9
Clf -0.0996 -0.0989 0.0007 -0.7
Clr -0.1561 -0.1186 0.0374 -24.0
CoP 0.6104 0.5453 -0.0651 -6.5
L/D -0.5643 -0.4786 0.0856 -15.2

  • Control : Re-calc. fp024d / Side Mirror - 30mm Higher & 20mm Outer

The drags and the front downforces are almost the same, but the rear downforce decreased significantly at the model with updates.

Some low pressure areas are decreasing on the bottom side of the stepped floor and the rear bumper.

Although the rear downforce is decreasing, since it is a model which the car designs are more applied to, simulations will be based on this model afterwards.


#4

Radiator Models

I tried to set porous media as a radiator simulation model, but I failed to make ‘cellZone’ for porous media in my project. So I made simple radiator models with many square holes.

  • Radiator Model : 20mm x 20mm Square Holes
    • 14 x 9 = 126 Holes / 30mm Pitch / Depth 35mm
    • Duct Area = 120523.294 (+/- 0.00023) mm2
    • Not Hole Area = 70123.2943 (+/- 0.00023) mm2
    • Opening 41.8% : (120523.294-70123.2943)/120523.294 = 0.41817642073
  • Radiator Model : 10mm x 10mm Square Holes
    • 28 x 18 = 504 Holes / 15mm Pitch / Depth 35mm
    • Duct Area = 120523.294 (+/- 0.00023) mm2
    • Not Hole Area = 70123.2943 (+/- 0.00023) mm2
    • Opening 41.8% : (120523.294-70123.2943)/120523.294 = 0.41817642073

Radiator Model - None : Control

Radiator Model - 20mm x 20mm Holes

Radiator Model - 10mm x 10mm Holes


Coefficients of Forces on Body and Wheels

Coef. Control Difference 20mm x 20mm Difference 10mm x 10mm Remarks
Cm 0.0352 0.0001 0.0353 0.0003 0.0356
Cd 0.5637 0.0001 0.5637 0.0000 0.5638
Cl -0.1795 -0.0014 -0.1810 0.0004 -0.1806
Clf -0.0546 -0.0006 -0.0552 0.0005 -0.0547
Clr -0.1249 -0.0008 -0.1258 -0.0002 -0.1259
CoP 0.6959 -0.0009 0.6950 0.0022 0.6973
L/D -0.3185 -0.0025 -0.3210 0.0007 -0.3203
RF 0.2057 -0.0298 0.1760 -0.0403 0.1357 Radiator Flow m3/s
RF 1.0000 -0.1447 0.8553 -0.1957 0.6596 RF / Control

Coefficients of Forces on Body Only (without Wheels)

Coef. Control Difference 20mm x 20mm Difference 10mm x 10mm Remarks
Cm 0.0099 0.0002 0.0101 0.0003 0.0104
Cd 0.4545 0.0002 0.4548 0.0000 0.4548
Cl -0.2176 -0.0014 -0.2190 0.0002 -0.2188
Clf -0.0989 -0.0005 -0.0994 0.0004 -0.0990
Clr -0.1186 -0.0009 -0.1196 -0.0002 -0.1198
CoP 0.5453 0.0008 0.5461 0.0016 0.5476
L/D -0.4786 -0.0029 -0.4815 0.0005 -0.4811

  • Control : Model with Updates (No Radiator Model)

  • As the size of holes decreases, the radiator flow decreases.
  • The drags are almost the same in these cases
  • The difference of downforces between “20mm x 20mm” and “10mm x 10mm” is
    slightly smaller than that between “Control” and “20mm x 20mm”

Much smaller size of square holes like 5mm x 5mm needs meshes to be smaller by one step more.
Therefore, at the present stage, I test aerodynamic devices about the sidepod and radiator
with the radiator model of 10mm size square holes.


Raditator Flow - U Magnitude

Sidepod Origin - No Radiator

Sidepod Origin - Radiator 20mm x 20mm Holes

Sidepod Origin - Radiator 10mm x 10mm Holes


#5

Sidepod C / Radiator Duct C

The designs of the sidepod and the radiator duct were modified for some reasons as followings.

  • Exterior Design Modification
  • Larger Radiators
  • Larger Outlet

Differences of Sidepod C & Radiator Duct C from the origin

  • Sidepod C / Radiator Duct C
    • 27.5mm Higher at the Rear End
    • 40% Larger Rear End Outlet
      • Origin : 3939.8728 mm2
      • Sidepod C : 5529.3174 mm2
    • 9.4% Smaller Radiator Duct Intake
    • 10% Larger Radiator Duct C Size
      • 450mm x 330mm x 40mm (Origin : 450mm x 300mm x 40mm)
    • Radiator Duct C Model for CFD : 10mm x 10mm Square Holes
      • 28 x 20 = 504 Holes / 15mm Pitch / Depth 35mm (11% Larger than Origin)
      • Duct Area = 133471.58 mm2
      • Not Hole Area = 77471.5805 mm2
      • Opening 42.0% : (133471.58-77471.5805)/133471.58 = 0.41956497031

Coefficients of Forces on Body and Wheels

Coef. Control Sidepod C Difference Difference % Remarks
Cm 0.0356 0.0334 -0.0022 -6.2
Cd 0.5638 0.5632 -0.0006 -0.1
Cl -0.1806 -0.1770 0.0036 -2.0
Clf -0.0547 -0.0551 -0.0004 0.8
Clr -0.1259 -0.1219 0.0040 -3.2
CoP 0.6973 0.6888 -0.0085 -0.8
L/D -0.3203 -0.3143 0.0060 -1.9
RF 0.1357 0.1551 0.0194 14.3 Radiator Flow m3/s

Coefficients of Forces on Body Only (without Wheels)

Coef. Control Sidepod C Difference Difference % Remarks
Cm 0.0104 0.0080 -0.0024 -22.8
Cd 0.4548 0.4537 -0.0011 -0.2
Cl -0.2188 -0.2151 0.0036 -1.7
Clf -0.0990 -0.0995 -0.0006 0.6
Clr -0.1198 -0.1156 0.0042 -3.5
CoP 0.5476 0.5374 -0.0103 -1.0
L/D -0.4811 -0.4742 0.0069 -1.4
  • Control : Radiator Holes 10mm x 10mm

  • Rear downforce decreases about 3.5%
  • Front downforce is almost the same or slightly increases
  • Drag is almost the same or slightly decreases
  • Radiator Flow increases around 14.3%
    • This is a larger increase than the increase of the radiator hole areas.

Radiator Flow - U Magnitude

Sidepod Origin - Radiator 10mm x 10mm Holes

Sidepod C


#6

Sidepod Radiator Outlet Louvers

In order to increase the radiator flow, I tried several outlets on Sidepod C.

Some low pressure areas are found on the side wall of Sidepod C aft of the radiator as below.

Sidepod C - Pressure / Left View

5 outlet louvers on the side wall were designed as followings.

  1. Louver Lower
  2. Louver Lower / Top Half
  3. Louver Lower Backward
  4. Louver Lower Backward / Top Half
  5. Louver Upper

Sidepod C - Louvers

Sidepod C - Louver Lower

Sidepod C - Louver Lower / Top Half

Sidepod C - Louver Lower Backward

Sidepod C - Louver Lower Backward / Top Half

Sidepod C - Louver Upper


Coefficients of Forces on Body and Wheels

Coef. Sidepod C Louver Lwr Louver Lwr / Top Half Louver Lwr Bwd Louver Lwr Bwd / Top Half Louver Upr Remarks
Cm 0.0334 0.0322 0.0329 0.0312 0.0321 0.0311
Cd 0.5632 0.5636 0.5631 0.5628 0.5628 0.5637
Cl -0.1770 -0.1702 -0.1745 -0.1673 -0.1727 -0.1696
Clf -0.0551 -0.0529 -0.0544 -0.0524 -0.0542 -0.0537
Clr -0.1219 -0.1173 -0.1201 -0.1149 -0.1185 -0.1159
CoP 0.6888 0.6891 0.6883 0.6867 0.6860 0.6835
L/D -0.3143 -0.3019 -0.3098 -0.2972 -0.3069 -0.3008
RF 0.1551 0.2319 0.1939 0.2056 0.1857 0.2133 Radiator Flow m3/s
RF 1.0000 1.4955 1.2505 1.3259 1.1979 1.3756 RF / Control

Coefficients of Forces on Body Only (without Wheels)

Coef. Sidepod C Louver Lwr Louver Lwr / Top Half Louver Lwr Bwd Louver Lwr Bwd / Top Half Louver Upr Remarks
Cm 0.0080 0.0069 0.0075 0.0060 0.0069 0.0059
Cd 0.4537 0.4557 0.4542 0.4550 0.4541 0.4555
Cl -0.2151 -0.2083 -0.2126 -0.2053 -0.2109 -0.2077
Clf -0.0995 -0.0973 -0.0988 -0.0967 -0.0986 -0.0980
Clr -0.1156 -0.1110 -0.1138 -0.1086 -0.1123 -0.1097
CoP 0.5374 0.5330 0.5354 0.5291 0.5326 0.5282
L/D -0.4742 -0.4570 -0.4681 -0.4512 -0.4644 -0.4559

  • Drags are almost the same in these cases
  • “Louver Lwr” is the best for Radiator Flow increase
  • “Louver Lwr / Top Half” is the least decrease of Clf, Clr and Cl
  • “Louver Lwr” and “Louver Lwr / Top Half” are efficient

Sidepod C - Louvers / Pressure - Left View


Sidepod C - Louvers / Pressure - Sectional Top View


Sidepod C - Louvers / U Magnitude at Z=220mm


Radiator Flow - U Magnitude

Sidepod C

Sidepod C - Louver Lwr

Sidepod C - Louver Lwr / Top Half

Sidepod C - Louver Lwr Bwd

Sidepod C - Louver Lwr Bwd / Top Half

Sidepod C - Louver Upr


#7

Radiator Duct D

Radiator Duct D was tested for improving the distribution of the radiator flow.
A shape of radiator duct outer wall is modified to a curving shape in “Radiator Duct D” as shown below.

Radiator Duct C

Radiator Duct D


Coefficients of Forces on Body and Wheels

Coef. Duct C Duct D Difference Difference % Remarks
Cm 0.0334 0.0334 0.0000 -0.1
Cd 0.5632 0.5634 0.0002 0.0
Cl -0.1770 -0.1770 0.0001 0.0
Clf -0.0551 -0.0551 0.0000 0.0
Clr -0.1219 -0.1219 0.0001 -0.1
CoP 0.6888 0.6886 -0.0002 0.0
L/D -0.3143 -0.3141 0.0002 -0.1
RF 0.1551 0.1572 0.0021 1.4 Radiator Flow m3/s

Coefficients of Forces on Body Only (without Wheels)

Coef. Duct C Duct D Difference Difference % Remarks
Cm 0.0080 0.0080 -0.0001 -1.0
Cd 0.4537 0.4539 0.0002 0.0
Cl -0.2151 -0.2149 0.0002 -0.1
Clf -0.0995 -0.0995 0.0000 0.0
Clr -0.1156 -0.1154 0.0002 -0.2
CoP 0.5374 0.5371 -0.0003 0.0
L/D -0.4742 -0.4735 0.0007 -0.1

  • Downforces and Drag are the same
  • Radiator Flow increases around 1.4%
    • Less effective than the improvements by Outlet Louvers
  • Radiator Flow Distribution seems to be improving slightly as shown below

Radiator Flow - U Magnitude

Sidepod C - Radiatro Duct C

Sidepod C - Radiator Duct D


#8

Radiator Duct Turning Vanes

Radiator Duct Turning Vanes were tested for improving the distribution of Radiator Flow.

Vertical Fillet

Turning Vane - Vertical

Turning Vane - Vertical 2 pcs

Turning Vane - Horizontal

Turning Vane - Horizontal B


Coefficients of Forces on Body and Wheels

Coef. Control V Fillet V 1pc V 2pcs H H-B Remarks
Cm 0.0334 0.0333 0.0332 0.0333 0.0332 0.0330
Cd 0.5634 0.5624 0.5633 0.5631 0.5630 0.5625
Cl -0.1770 -0.1771 -0.1767 -0.1768 -0.1762 -0.1756
Clf -0.0551 -0.0552 -0.0551 -0.0552 -0.0549 -0.0548
Clr -0.1219 -0.1218 -0.1216 -0.1217 -0.1213 -0.1208
CoP 0.6886 0.6880 0.6879 0.6881 0.6886 0.6878
L/D -0.3141 -0.3148 -0.3137 -0.3140 -0.3129 -0.3122
RF 0.1572 0.1566 0.1589 0.1591 0.1602 0.1616 Radiator Flow m3/s
RF 1.0000 0.9967 1.0111 1.0120 1.0192 1.0285 RF / Control

Coefficients of Forces on Body Only (without Wheels)

Coef. Control V Fillet V 1pc V 2pcs H H-B Remarks
Cm 0.0080 0.0079 0.0077 0.0078 0.0078 0.0075
Cd 0.4539 0.4529 0.4538 0.4536 0.4534 0.4530
Cl -0.2149 -0.2150 -0.2145 -0.2147 -0.2142 -0.2135
Clf -0.0995 -0.0996 -0.0995 -0.0995 -0.0993 -0.0992
Clr -0.1154 -0.1154 -0.1150 -0.1152 -0.1149 -0.1143
CoP 0.5371 0.5366 0.5360 0.5364 0.5363 0.5352
L/D -0.4735 -0.4748 -0.4728 -0.4734 -0.4725 -0.4713
  • Control : Radiator Duct D

  • Drags and Downforces of Vertical Fillet and Vertical Turning Vanes are the same with Control
  • Rear Downforce decreases slightly in the case of Horizontal Turning Vanes
  • Radiator Flow increases 2.9% at most in “Truning Vane - Horizontal B”
    • Less effective than the improvements by Outlet Louvers
  • Radiator Flow Distribution improves in the all case of Turning Vanes as shown below

Radiator Flow - U Magnitude

Sidepod C - Radiator Duct D

Sidepod C - Radiator Duct D / Vertical Turning Fillet

Sidepod C - Radiator Duct D / Turning Vane - Vertical

Sidepod C - Radiator Duct D / Turning Vane - Vertical 2pcs

Sidepod C - Radiator Duct D / Turning Vane - Horizontal

Sidepod C - Radiator Duct D / Turning Vane - Horizontal B


#9

Summary


  • Model with Updates
    • The rear suspension openings decreased the rear downforce significantly
  • Sidepod Outlets
    • The radiator flow increased around 50% at the maximum
      • The sidepod outlets decreased the downforces at the maximum around 6%
    • “Louver Lwr” and “Louver Lwr / Top Half” are efficient
      • It is necessary to adopt efficient outlets according to the required cooling capacity
  • Radiator Duct Modifications
    • The modifications of the radiator ducts increased the radiator flow around 3% at the maximum, but they are much smaller than the increases by the sidepod outlets
      • For increasing the radiator flow, it is more effective to install aerodynamically efficient outlets
    • The modifications of the radiator ducts improved the radiator flow distributions.
      • There is a possibility that the cooling capacity can be improved more with some radiator duct modifications according to the flow path of the radiator coolant