Experimental investigation of the local heat transfer of impinging cooling with outflow film in closed small space

Experiments were carried out to investigate the heat transfer of compound cooling（impinging cooling with outflow film）.Local heat transfer coefficients on inner surface were obtained over a Reynolds number range of 10 000～40 000,nozzle-to-plate spacing H/D range of 0.17～2.0,the ratio between impinging jet and film hole distance to jet hole diameter P/D range of 0 and 1.Experimental results show that the local heat transfer coefficient was affected by impingement Reynolds number and nozzle-to-plate spacing greatly.Under the parameters in this paper,the local Nu number increased with the impingement Reynolds number.When P/D=0,the maximum Nu number was achieved while H/D=2.When P/D increased to unity,the maximum Nu number was gotten while H/D=2 and 0.17 under lower impingement Reynolds number.And this proper value of H/D will change to be 2 and 1 under higher impingement Reynolds number.