Experimental investigation on flow and heat transfer of jet impingement inside a semi-confined smooth channel

Experimental investigation is conducted to investigate the flow and heat transfer performances of jet impingement cooling inside a semi-confined smooth channel. Effects of jet Reynolds number (varied from 10 000 to 45 000), orifice-to-target spacing (zn=1d-4d) and jet-to-jet pitches (xn=3d-5d, yn=3d-5d) on the convective heat transfer coefficient and discharge coefficient are revealed. For a single-row jets normal impingement, the impingement heat transfer is enhanced with the increase of impingement Reynolds number or the decrease of spanwise jet-to-jet pitch. The highest local heat transfer is achieved when zn/d is 2. For the double-row jets normal impingement, the laterally-averaged Nusselt number distributions in the vicinity of the first row jets impinging stagnation do not fit well with the single-row case. The highest local heat transfer is obtained when zn/d is 1. A smaller jet-to-jet pitch generally results in a lower discharge coefficient. The discharge coefficient in the double-row case is decreased relative to the single-row case at the same impingement Reynolds number.