Find your FIT A Comparison of Strategies for Simulating Vehicle Heat - PowerPoint PPT Presentation

Find your FIT A Comparison of Strategies for Simulating Vehicle Heat Protection Test Cycles in 3D

The Thermal Management Process 2

The Thermal Management Process The ideal process minimizes the cost of each step Source Model Meshing Calculation Post Processing Inputs Construction Model Revision Communicate Results 3

What is the most effective thermal management process? • Needs to support high volume production work • Easily adapt to specialized jobs • Minimize resource requirements Source Model Post Meshing Calculation Inputs Construction Processing Model Revision Communicate Results 4

Find your FIT Calculation Method 1 FIT Speed (m/s) Method 2 Method 3 5

Simulation methods Approach to evaluation Results Conclusions 6

Different Strategies • CHT - Conjugate Heat Transfer • Step-wise • Psuedo Transient • 1D Surrogate • 2D surrogate 7

Methods Approach Results Conclusions Conjugate Heat Transfer • Solves as one solution • Very detailed 8

CFD Coupling CFD TAITherm Convection coefficients or fluid velocities & fluid temperatures (h and Tfluid) Surface temps (Twall) 9

Methods Approach Results Conclusions Step Wise Repeated Process CFD CFD HTC & Tf HTC & Tf Tw Tw Coupling Interval Transient Solid Domain - TAITherm Tw Tw Test Cycle Duration(s) 10

Methods Approach Results Conclusions Psuedo-Transient Time 0 1 2 3 4 5 6 7 8 9 1 TAITherm Initial Thermal Model (estimated convection) CFD 2 Steady-state repr. t=0 3 TAITherm Steady-state at t=0 CFD 4 Steady-state repr. t=4 5 TAITherm Transient from t=0 to t=4 CFD Steady-state repr. t=9 11

Methods Approach Results Conclusions Time 0 1 2 3 4 5 6 7 8 9 1 TAITherm Initial Thermal Model (estimated convection) CFD HTC and Tf Steady-state repr. t=4 Tw CFD 2 Steady-state repr. t=0 TAITherm 3 Transient from t=0 to t=4 TAITherm Steady-state at t=0 Run Thermal model with initial CFD CFD CFD Data from time = 4, after 1 st transient coupling 4 Steady-state repr. t=4 CFD Data from time = 0 5 loop Coefficient TAITherm Transfer Transient from t=0 to t=4 CFD Data from time = 4, CFD Heat prior to transient Steady-state repr. t=9 coupling Time

Pseudo-Transient Time 0 1 2 3 4 5 6 7 8 9 1 TAITherm Initial Thermal Model (estimated convection) CFD HTC and Tf Steady-state repr. t=4 Tw CFD 2 Steady-state repr. t=0 TAITherm 3 Transient from t=0 to t=4 TAITherm Steady-state at t=0 Run Thermal model with updated CFD CFD 4 Steady-state repr. t=4 5 Coefficient TAITherm Transfer Transient from t=0 to t=4 Heat CFD Steady-state repr. t=9 Time 13

Pseudo-Transient Time 0 1 2 3 4 5 6 7 8 9 1 TAITherm Initial Thermal Model (estimated convection) CFD Steady-state repr. t=4 CFD 2 Steady-state repr. t=0 TAITherm 3 Transient from t=0 to t=4 TAITherm Steady-state at t=0 Run Thermal model with updated CFD CFD 4 Steady-state repr. t=4 5 Coefficient TAITherm Transfer Transient from t=0 to t=4 Heat CFD Steady-state repr. t=9 Time 14

Methods Approach Results Conclusions Psuedo-Transient Time 0 1 2 3 4 5 6 7 8 9 1 TAITherm Initial Thermal Model (estimated convection) CFD 2 Steady-state repr. t=0 3 TAITherm Steady-state at t=0 CFD 4 Steady-state repr. t=4 5 TAITherm Transient from t=0 to t=4 CFD 6 Steady-state repr. t=9 TAITherm Transient from t=4 to t=9 15

Methods Approach Results Conclusions Surrogate Modeling Process Compute a steady Run transient thermal model Sample range of Fit an equation to the state CHT solution using surrogate model to vehicle operating convective boundary at each operating approximate convective conditions conditions condition boundary conditions Uniform Linear Leveraged Existing 1D Coupled CHT Sampling of Interpolation Software Features solutions Vehicle Speed OLHC of Vehicle Speed and Inlet Gaussian Coupled CHT 2D Custom Developed Temperature Anisotropic solutions Coupling Harness Kriging 16

Methods Approach Results Conclusions Traditional Conjugate Heat Stepwise Transient Surrogate Models Psuedo Transient Transfer Simulation Reduced runtimes • Reduced runtimes • Reduced runtimes • Pros High Accuracy • Models can be reused • Flexible resource • Flexible resource • Easiest process • Flexible resource allocation • allocation allocation Flexible post analysis • options Many samples required Complex process • • Large computational Steady fluids • • Cons Complex process Steady state fluid • • costs assumption assumptions • Steady sample point Inflexible resource • assumption allocation 17

CoTherm Process automation software from ThermoAnalytics

The Thermal Management Process • CoTherm Source Model Meshing Calculation Post Processing Inputs Construction Model Revision Communicate Results 19

Drive Cycle Extension – 1D Surrogate • CoTherm • Determines coupling points based on Drive Cycle Profile • Inputs: • Output: • Runs steady thermal-CFD cases • Thermal/CFD models • Transient thermal • Imports CFD results into model • Drive cycle data transient thermal model • Runs transient thermal model 20

Psuedo Transient Method • CoTherm • Automatically sets up SS CFD models • Inputs: • Output: • Couples Thermal and • Base Thermal/CFD • Merged thermal CFD models models model with all CFD • Merges thermal points • Boundary conditions models • Coupling interval 21

Methods Approach Results Conclusions Selected highly simplified engine • bay geometry 34,602 surface elements • 275,748 volume elements • 22

Methods Approach Results Conclusions Head 1400 400 Manifolds 350 1200 300 Block 1000 250 HTC (w/m2K) 800 Tf(K) 200 Crank Case 600 150 400 100 200 50 0 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Time (s) HTC Tf 23

Methods Approach Results Conclusions Inlet 16 335 14 330 12 325 Inlet Temperature (K) Inlet Speed (m/s) 10 320 8 315 6 310 Pressure Outlet 4 305 2 300 0 295 0 500 1000 1500 2000 Time (s) Inlet Speed Inlet Temperature Pressure Outlet 24

Methods Approach Results Conclusions Cycle 1 Cycle 2 Cycle 3 40 40 40 35 35 35 30 30 30 25 25 25 Speed (m/s) Speed (m/s) Speed (m/s) 20 20 20 15 15 15 10 10 10 5 5 5 0 0 0 0 500 1000 0 500 1000 1500 2000 0 1000 2000 3000 4000 Time (s) Time (s) Time (s) Duration (s) 1350 1800 3600 31.4 36.5 Max Speed (m/s) 38.8 18.6 Avg. Speed (m/s) 12.9 18.0 Volatility 0.06 0.27 2.98 25

Methods Approach Results Conclusions Cycle 1 Cycle 2 Cycle 3 26

Methods Approach Results Conclusions 6 node average Stepwise Transient Prediction - Temperature Cycle 2 Cycle 3 Cycle 1 420 40 550 45 440 40 35 400 420 500 35 30 Vehicle Speed (m/s) 400 380 Vehicle Speed (m/s) 30 Temperature (K) Temperature (K) 25 Temperature (K) 450 25 380 360 20 20 360 400 15 340 15 340 10 10 350 320 320 5 5 300 0 300 300 0 0 500 1000 1500 2000 2500 3000 3500 0 500 1000 1500 2000 0 200 400 600 800 1000 1200 1400 Time (s) Time (s) Time (s) CHT Stepwise - 30s Vehicle Speed CHT Stepwise - 30s Vehicle Speed 27

Methods Approach Results Conclusions Surrogate Model Transient Prediction – 6 node average Temperature Cycle 1 Cycle 2 Cycle 3 440 40 550 45 35 440 40 35 420 30 500 420 35 30 400 25 Vehicle Speed (m/s) 30 Vehicle Speed (m/s) 400 Vehicle Speed (m/s) Temperature (K) Temperature (K) 25 Temperature (K) 450 380 20 25 380 20 20 360 15 400 360 15 15 340 10 10 340 10 350 320 5 5 320 5 300 0 300 0 300 0 0 500 1000 0 500 1000 1500 2000 0 500 1000 1500 2000 2500 3000 3500 Time (s) Time (s) Time (s) CHT 1D Surrogate 2D Surrogate Vehicle Speed CHT 1D Surrogate CHT 1D Surrogate 2D Surrogate Vehicle Speed 2D Surrogate Vehicle Speed 28

Methods Approach Results Conclusions 6 node average Psuedo Transient Prediction – Temperature Cycle 2 Cycle 3 Cycle 1 550 45 420 40 440 40 35 400 500 420 35 30 Vehicle Speed (m/s) 380 Vehicle Speed (m/s) 30 400 Temperature (K) Temperature (K) Temperature (K) 25 450 25 380 360 20 20 400 360 15 340 15 10 340 10 350 320 5 320 5 300 0 300 0 300 0 500 1000 1500 2000 0 200 400 600 800 1000 1200 1400 0 1000 2000 3000 Time (s) Time (s) Time (s) CHT Psuedo-Transient 30s Vehicle Speed CHT Psuedo-Transient 30s Vehicle Speed 29

Methods Approach Results Conclusions Manifold 6.0 Cycle 1 Cycle 2 Cycle 3 6 node 5.0 average 4.0 Total Accuracy RMSE (K) 4 3.0 3.5 2.0 3 1.0 2.5 RMSE(K) 0.0 2 1D Surrogate 2D Surrogate Stepwise - 30s Psuedo-Transient 30s 55 node 1.5 Top Wall average 6.0 1 Cycle 1 Cycle 2 Cycle 3 5.0 0.5 4.0 0 RMSE (K) 1D Surrogate 2D Surrogate Stepwise - 30s Psuedo-Transient 3.0 30s 2.0 1.0 0.0 30 1D Surrogate 2D Surrogate Stepwise - 30s Psuedo-Transient 30s