Numerical Study of Flow Fields and Heat Transfer Characteristics in an Impinging Slot Jet With Buckling Phenomenon

Plane impinging slot jet is widely used in a variety of industrial fields such as the cooling and coating system. In these systems, flow stability of the jet is the most important factor to obtain good products. But, in some operating cases it was found that there are alternating plane-wise vortices near the impinging stagnation region, and that such alternating vortices move almost periodically to the right and left sides along the stagnation line due to the jet flow instability and the pressure force balance, and then high and low temperature points are appeared periodically along the stagnation line. This instability is closely related to buckling of the jet center sheet. And, this instability of the flow fields causes the non-uniform heat transfer characteristic in the impinging region. In order to verify these flow fields and heat transfer characteristic, impinging slot jet system has been investigated numerically by using a commercial 3-D flow analysis code, FLUENT. At here, Reynolds number is about 10,000 and L/d is 6.67 as geometric conditions where d is the nozzle width and L is the nozzle-to-plate distance. LES turbulent model is used to obtain instantaneous flow fields near the jet exit and on the plate.