Experimental study of heat transfer from round nozzle impinging jet

Local heat transfer characteristics were investigated experimentally by naphthalene sublimation mass/heat transfer analogy technique for plate cooled by single round nozzle air jet.The relative spacing(H/D) between nozzle and plate was ranging form 1 to 12,the Reynolds number was ranging from 7×10~3 to 1.9×10~4.By analyzing the experimental data,some useful heat transfer performances were obtained.The Nusselt number is nearly the same for the same radius and its value is strongly influenced by the Reynolds.The Nusselt number varies non monotonous along axis for the same Reynolds number,and the peak appears when the value of H/D is about 6.The local Nusselt number has two peaks for different R/D as the value of H/D is less than 6,its value decreases with the increase of H/D,while the influence region is expended.