Research on internal flow field analysis and power loss modeling of the expansion seal ring

Expansion seal rings are widely used in automobile transmission systems, and their sealing performance plays a vital role in the pressure stability and transmission efficiency of the transmission system. However, investigations into revealing the internal flow mechanism of the expansion seal ring and predicting the power loss of the expansion seal ring are still insufficient. In this study, a two-way fluid-structure interaction model consisting of the shaft, oil sleeve, and expansion seal ring was established. The flow and structural physical fields under a series of operating conditions were simulated, and the effects of oil temperature, rotational speed, and seal pressure differential on leakage rate, deformation, power loss, and contact pressure were analyzed. Further, a power loss prediction model was developed by multiple linear regression method. The results demonstrate that in the internal flow field, the oil flow into and out of the groove is characterized by backward step flow and jet flow, respectively. In the structural field, the maximum deformation and the maximum contact pressure of the main sealing surface appear at the notch of the expansion seal ring, and the seal pressure differential has the most significant influence on it. The relative error between the predicted value of the developed model and experimental values is within 9%, which meets the industrial requirements. This work facilitates scholars to understand the internal flow mechanism and deformation process of expanding seal rings and provides a method to predict sealing ring power loss.