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AMESim Fan Drive Thermal Model

CAViDS Consortium. AMESim Fan Drive Thermal Model. A CAViDS Consortium Project. Advisory Committee Report August 22, 2012. CAViDS Consortium. Project Objective.

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AMESim Fan Drive Thermal Model

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  1. CAViDS Consortium AMESim Fan Drive Thermal Model A CAViDS Consortium Project Advisory Committee Report August 22, 2012

  2. CAViDS Consortium Project Objective Develop heat generation modeling capability for Model 662B viscous fan drive to predict temperature rise for general operating conditions. This model will be used in conjunction with CFD modeling to determine enhanced design for higher heat rejection from the drive. Higher heat rejection will allow longer operation at fan drive speeds that allow optimal vehicle operation.

  3. CAViDS Consortium Work Plan 1. Develop AMESim thermal model based on heat flow predictions from previous modeling, within AMESim and from available literature Compare temp rise measurements with AMESim predictions for six operating conditions Determine predicted heat flow throughout drive for these operating conditions Perform CFD analysis on convective heat flow from body of drive for a selected operating conditions Determine effect of fan drive body rib configuration on convective heat flow with CFD Incorporate CFD results into AMESim model through empirical relationships established Convert AMESim model into Borg Warner compatible software to be used as a design tool

  4. CAViDS Consortium AMESim Thermal Model

  5. CAViDS Consortium AMESim Thermal Model • Used proven simple transmission based basic approach for fluid convection, bearing and linear conduction, and radiation • Used external convection-to-air equations based on technical paper (Nusselt number = 0.019 * Re ^0.8) • Developed new sub-models for fluid convection to link heat transfer equations to instantaneous fluid properties and speed variation • Developed new sub-models for air convection based on variable drive speed as input to convection equations • Input silicon fluid properties in table as fluid reference • Used rib spacing as critical dimension for Reynolds number for air convection from body • Used fluid gap between grooves as critical dimension for Reynolds number for fluid convection to body and clutch

  6. CAViDS Consortium Temp Rise Prediction Results • End temperature of fluid is close • Cause of early fluid temperature discrepancy is TBD

  7. CAViDS Consortium Heat Flow Predictive Results End Conditions Watts Input Heat Flow 2842 Fluid Convection to Drive Body Cover 1417 Fluid Convection to Rear Drive Body 1173 Fluid Convection to Clutch Plate 254 Fluid Convection to Reservoir 7 Drive Body Cover Convection to Air 1291 Rear Drive Body Convection to Air 876 Drive Body Cover Radiation to Air 153 Rear Drive Body Radiation to Air 105 Rear Drive Body Conduction to Fan 58 Clutch Plate Conduction to Engine 37 Other (including heating of parts) 380

  8. CAViDS Consortium Non Steady State Test Conditions

  9. CAViDS Consortium Preliminary Parametric Sensitivity Effect of enhancing parameter by factor of two in end fluid temperature Baseline end fluid temperature 234 C Double drive body area -53 C Halve drive body critical length -11 C Double drive body/clutch fluid groove area - 8 C Halve drive body/clutch fluid critical length - 5 C Change radiation emissivity from 0.62 to 1 - 5 C Double fluid volume 0 C

  10. CAViDS Consortium Conclusions to Date • Need constant speed testing at less than 3 HP slip heat at various fan speeds to determine end steady state thermal conditions (heat flow and part temperatures) without exceeding silcone 450 F temperature limit. This will allow significant model simplification and parametric variation of speed and torque. • Need to measure temperature of oil, clutch plate, and body halves to correlate to predictions. to explain discrepancies in oil temperature rise between measured and predicted results, and to tune fluid convection parameters • Overall fan drive heat rejection is primarily through convection from body to air • Body area is most sensitive body-to-air convection parameter discovered to date • Integration is by DASSL (Adams and Back Differentiation Function) techniques with Jacobian evaluations. Minimum step size is 2E-15 second. Maximum step size is 0.22002 second. Over 47000 steps were used over a 693 second simulation.

  11. CAViDS Consortium Next Month • Document integration techniques for our simulations • Perform literature search on convection from rotating disks • Perform simulations with actual active groove area covered by silcone fluid for each condition and actual gap dimension used as the critical length for the fluid convection Reynolds number. • Start on CFD simulations of flow conditions

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