Study on the Aspiration Effect of Glassrun Seal System Based on Time-Varying Pressure Difference Between Vehicle Exterior and Interior

When the vehicle is driven at high speed, there exist very complex flow and vortex shedding phenomenon at the side window area with intense pressure fluctuations. When the dynamic pressure difference between vehicle exterior and interior is large enough, the side window sealing system is prone to poor sealing and generates leakage noise, which can severely affect vehicle interior acoustic comfort. To study the dynamic aspiration mechanism of the sealing system, a nonlinear finite element model of the glassrun seal was established to simulate the quasi-static installation deformation process of the sealing strip, and to obtain the deformed geometric shape and residual stress. Then, the exterior flow field of the glassrun sealing area of a simplified vehicle model was calculated with CFD simulation to obtain the hydrodynamic pressure excitation acting on the outer surface of the sealing strip at different vehicle speeds, and the results were subsequently validated through wind tunnel testing. With ALE (Arbitrary Lagrangian-Eulerian) numerical method, mesh morphing and overset mesh techniques were used to achieve fluid-structure interaction boundary motion and effective closure of the wall boundary gap. In this way, a nonlinear dynamic model of the coupled sealing structure and flow field was established. Considering factors such as contact friction model, the forced vibration response and sealing aspiration condition of the sealing strip under actual excitation of time-varying pressure difference was analyzed. When the hydrodynamic pressure fluctuation intensity on the outer surface of the glassrun seal is 34%, and the average pressure difference reaches approximately 1700Pa, the contact state between the seal and the side window becomes unstable, with a noticeable and sustained fluctuation on the contact area, consequently resulting in aspiration. These findings are of significant importance for optimization of the side window sealing system and precaution of aspiration noise.