R. Tarighi - Master of Science in Mechanic Engineering, Semnan University, Semnan, Iran.
M. Rajabi Zargarabadi - Assistant professor,Semnan University, Semnan, Iran.

In today s industry, one of the relatively modern and effective methods for cooling hot parts is impingement heart transfer. Impinging jets have attracted a great deal of attention from researhers due to having a high heat transfer rate. In this method, by applying a considerable momentum to a fluid exiting from a nozzle and then forming a thin hydrodynamic and thermal layer on the impinging surface, considerable improvement was obtained in the increase of mass, heat, momentum transfer.