CAViDS Consortium

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.
CAViDS Consortium
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CAViDS Consortium
1.
Develop AMESim thermal model based on heat flow predictions from previous modeling, within AMESim and from available literature
2.
Compare temp rise measurements with AMESim predictions for six operating conditions
3.
Determine predicted heat flow throughout drive for these operating conditions
4.
Perform CFD analysis on convective heat flow from body of drive for a selected operating conditions
5.
Determine effect of fan drive body rib configuration on convective heat flow with CFD
6.
Incorporate CFD results into AMESim model through empirical relationships established
7.
Convert AMESim model into Borg Warner compatible software to be used as a design tool
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CAViDS Consortium
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CAViDS Consortium
• 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
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CAViDS Consortium
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CAViDS Consortium
End Conditions
Input Heat Flow
Fluid Convection to Drive Body Cover
Fluid Convection to Rear Drive Body
Fluid Convection to Clutch Plate
Fluid Convection to Reservoir
Drive Body Cover Convection to Air 1291
Rear Drive Body Convection to Air
Drive Body Cover Radiation to Air
Rear Drive Body Radiation to Air
Rear Drive Body Conduction to Fan
Clutch Plate Conduction to Engine
Other (including heating of parts)
Watts
2842
1417
1173
254
7
876
153
105
58
37
380
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CAViDS Consortium
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CAViDS Consortium
Effect of enhancing parameter by factor of two in end fluid temperature
Baseline end fluid temperature
Double drive body area
234 C
-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
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CAViDS Consortium
1. 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.
2. 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
3. Overall fan drive heat rejection is primarily through convection from body to air
4. Body area is most sensitive body-to-air convection parameter discovered to date
5. 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.
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CAViDS Consortium
1. Document integration techniques for our simulations
2. Perform literature search on convection from rotating disks
3. 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.
4. Start on CFD simulations of flow conditions
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