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In this study, friction-induced vibrations of the window sealing system of a vehicle were investigated using a detailed numerical model. A lumped element, single-degree-of-freedom model was first developed for verification of the numerical procedures. An approximate expression for the frequency of the stick-slip oscillations was obtained. The model indicated that the frequency decreased as the normal force and the difference between the static and kinetic friction coefficients were increased. Stick-slip oscillations were then simulated using a finite element model of a glass run seal using an explicit time marching method. The motion of the seal during the slipping phase was in the direction of the friction force. The peak frequency was found to vary according to the glass position on the seal surface. The results indicated that both the periods of the stick and slip phases of the seal motion affect the frequency of the stick-slip oscillations.

Notched spoilers have been observed to be more effective than uniform spoilers to suppress the flow-induced cavity resonance of vehicles with open sunroofs. In this study, a few mechanisms possibly involved in buffeting suppression from notched spoilers were investigated experimentally and numerically. One objective was to investigate the spatial coherence and phase of the wall pressure fluctuations downstream of notched spoilers in comparison with the same quantities for uniform spoilers. Another objective was to gather detailed measured data to allow the verification of computer simulations of the flow over the notched spoiler. Experiments were performed to measure the velocity and wall pressure fields downstream of spoilers mounted on the rigid floor of a closed test section wind tunnel for different spoiler heights. Efforts were made to reproduce the spoiler and wind tunnel geometry and boundary conditions of the experimental set-up in the numerical simulations.