A combined numerical and experimental investigation of disengaged wet brake plate power loss

Increased machine performance through reduction of drivetrain power losses is an important goal in powertrain engineering. One key area of power loss in the driven axles of heavy on-road vehicles and off-highway vehicles is the disengaged wet brake conjunctions. The resultant power loss, particularly under cold start conditions, can be quite significant. The addition of patterned grooves into the brake friction linings assists lubricant flow to dissipate heat during contact, which complicates the prediction of performance, making design improvement a multi-variate problem. A Reynolds-based numerical model with the inclusion of lubricant inertial terms is developed, allowing time efficient prediction of the conjunctional torsional viscous losses. The numerical model is validated with CFD as well as experimental measurements, using a developed component based test rig. Good agreement is found for predictions against measurements for lower viscosity lubricant flow at higher bulk oil temperatures. The results show deviations at lower temperatures promoting higher viscosity inlet starvation, which is not taken into account with the assumed fully flooded inlet.