Aerodynamic optimization of Chalmers Formula Student Vehicle. STAR - - PowerPoint PPT Presentation

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Aerodynamic optimization of Chalmers Formula Student Vehicle. STAR - - PowerPoint PPT Presentation

Feb 12, 2023 155 likes ā€¢507 views

Aerodynamic optimization of Chalmers Formula Student Vehicle. STAR Global Conference 2014,Vienna Tzanakis Athanasios Presentation Layout Problem description. Approaching the optimum solution. Goals definition. Simulations

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SLIDE 1

Aerodynamic optimization

  • f Chalmers Formula

Student Vehicle.

STAR Global Conference 2014,Vienna

Tzanakis Athanasios

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SLIDE 2

Presentation Layout

  • Problem description.
  • Approaching the optimum solution.
  • Goals definition.
  • Simulations methodology.
  • Areas of interest.
  • Results.
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SLIDE 3

The problem

The average speed of a Formula Student vehicle is approximately 56kph. What is the contribution of aerodynamics in vehicles performance in such a low speed?

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SLIDE 4

Approaching the optimum solution

Ideas Mathematical calculations Design 2D Simulations 3D Simulations

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SLIDE 5

Aerodynamics necessity

62 64 66 68 70 72 74 76

NO AERO AERO

Lapā€™s Time (s)

160 kg 180 kg 200 kg 220 kg

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SLIDE 6

Goals

Design Targets Downforce 500-550 N at 56 km/h Drag 200-250 N Down force/Drag ratio 2.75 Mass flow over radiator 0.42 kg/s Weight 16 kg

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SLIDE 7

Ideas

Front wing Rear wing Sidepods Diffuser

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SLIDE 8

Simulations on STAR-CCM+ 3D 2D

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SLIDE 9

2D Simulations

Physics:

  • Steady state
  • Segregated flow
  • Realizable š‘™āˆ’šœ
  • two-layer treatment

Observables:

  • Airfoil profile
  • Angle of attack
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SLIDE 10

3D Simulations

Surface mesh

  • Ansa
  • Star-CCM+ Surface wrapper

Volume mesh

  • Star-CCM+

Solver

  • Star-CCM+

Post Processing

  • Star-CCM+
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SLIDE 11

Mesh and refinement boxes

  • Wind tunnel (4Lx4Lx20L)
  • 6 refinement boxes
  • Polyhedral mesh mainly
  • Aligned mesh for radiator
  • 3 prism layers
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SLIDE 12

Mesh and refinement boxes

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SLIDE 13

Defining the physics

Models Realizable k-Īµ, Standard wall function Steady State Segregated Free flow velocity 15.6m/s Floor boundary condition 15.6 m/s Wheels MRF zone Coefficient of inertial resistance in radiator (184.3 kg/m3 , 184.3 Ɨ102 kg/m3, 184.3 Ɨ102 kg/m3) Coefficient of porous resistance in radiator (222.6 kg/m3s, 222.6 Ɨ102 kg/m3s, 222.6 Ɨ102 kg/m3s) Iterations 1000

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SLIDE 14

Wings set up Diffuser

  • ptimization

Mass Flow

  • ver

radiator Brake cooling

Areas of interest

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SLIDE 15

Front Wing Development

Not well balanced vehicle.

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SLIDE 16

Front Wing Evaluation

170 175 180 185 190 195 200 205 210 215 220 225 Two-element wing Three element wing Three element wing 2nd conf.

Local Downforce (N) Total Drag (N)

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SLIDE 17

Rear wing development and evaluation

50 100 150 200 250 Three element wing Three element wing 2nd conf.

Local Downforce (N) Total Drag (N)

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SLIDE 18

Endplates shape evaluation

50 100 150 200 250 Endplate concept 1 Endplate concept 2 Endplate concept 3 Newtons

Rear Endplates

Local Downforce (N) Total Drag (N)

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SLIDE 19

FEM on rear wing

Case Carbon H35 Total Weight Deflection 0.3mm - 3 Ribs(13x15mm) 0.863 0.26411 1.12711 7.6985 0,3mm - No Rib(12x15mm) 0.863 0.276 1.139 9.0616 0.3mm - 3 Ribs(13x17,5mm) 0.863 0.284 1.147 7.1847 0.3mm - 3 Ribs(16x15mm) 0.863 0.2947 1.1577 7.45 0.3mm - 3 Ribs(13x20mm) 0.863 0.3083 1.1713 6.8529 0.3mm - 3 Ribs Bigger Rear 0.863 0.322 1.185 6.9075 0.3mm - 3 Ribs(20x15mm) 0.863 0.334 1.197 7.334 0,33mm - 1 Rib(12x15mm) 0.863 0.371 1.234 9.0215 0.3mm - 3 Ribs+Nomex 0.94 0.3083 1.2483 6.83

FEM by Elanghovan Natesen natesan@student.chalmers.se

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SLIDE 20

Diffuser Development

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SLIDE 21

Diffuser Evaluation

Efficiency increased by 26%

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SLIDE 22

Diffuser Evaluation

Not interaction between flap and diffuser.

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SLIDE 23

FEM on diffuser

FEM by Elanghovan Natesen natesan@student.chalmers.se

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SLIDE 24

Sidepod development

Gap for radiator cooling.

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SLIDE 25

Sidepod evaluation

Massflow: 0.3 kg/s Massflow: 0.46 kg/s

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SLIDE 26

Brake cooling

The problem:

Overheated disk brakes effected vehicle stability and braking distance.

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SLIDE 27

Brake cooling

Many different geometries in limited area so Star-CCM+ surface wrapper was directly applied.

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SLIDE 28

Brake evaluation

135 140 145 150 155 Neutral Short duct Long duct W/m2-K

Heat transfer coef.

Local heat transfer coefficient

Initial Final

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SLIDE 29

Full vehicle simulations

Test Angle(deg) Velocity(m/s) Mx(Nm) My(Nm) Mz(Nm) Fx(N) Fy(N) Fz(N) Yaw 15.6 5.73

  • 194.4

2.57 222 2.47

  • 410

Yaw 5 15.6

  • 4.1
  • 184.5
  • 29.4

227.7 45.6

  • 409

Roll 1.2 15.6

  • 1.55
  • 199

7.75 220

  • 9.57
  • 392
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SLIDE 30

Results

Design Targets Goals Final objectives Downforce 500-550 N at 56 km/h 462 N at 56 km/h Drag 200-250 N 234 Down force/Drag ratio 2.75 1.97 Mass flow for radiator 0.42 kg/s 0.46 Weight 16 kg 10kg

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SLIDE 31

Rendering by Bjorn Schlingmann Bjoern.schlingmann@gmail.com

Thank you!

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SLIDE 32

Thank you!

Rendering by Bjorn Schlingmann Bjoern.schlingmann@gmail.com

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SLIDE 33

Questions ?

Rendering by Bjorn Schlingmann Bjoern.schlingmann@gmail.com