The aerodynamic noise and the wake flow field in a cooling fan under actual operating conditions are studied with and without winglets on the fan blades. In order to understand the influence of the winglet, the aerodynamic noise and the wake velocity distribution are measured. The results indicated that overall noise level decreased and the noise spectrum was changed in a low frequency range when the winglet was installed. It was found from the flow visualization and PIV measurement that the influence of the winglet appeared in the traces of the tip vortices and the magnitude of vorticity was reduced in the near wake region, which suggest the observed reduction in aerodynamic noise.

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Automobile wiper systems provide a clear sight for drivers by creating a very thin layer of water about few dozen nano meters on a windshield. Several studies have been carried out to investigate the dynamic behavior of the wiper systems. However, there are few studies focused on reversal behavior of the wiper blade. Observation was conducted and analytical model is developed from the observation of the real wiper system. A water layer is considered in the analytical model between the wiper blade and the glass surface. The bottom of the model is assumed to always contact the water layer so that the fluid force is always applied. The dimensionless equations, which govern the wiping motion including the reversal behavior, were derived. The equations are discussed neglecting the nonlinear terms to understand the approximate movement and effect of the parameters. Moreover, the equation is solved numerically to obtain the time histories of the wiper blade. As a result, the effect of the fluid force, which acts on the wiper blade on the reversal behavior of the wiper blade, became clear.