Effects of cross-flow mach number on flow and heat transfer characteristics around effusion hole

Heat transfer and flow characteristics in a rectangular channel with 90° and 45° effusion hole under the cross-flow Mach number of 0.2 and 0.7 have been numerically studied. The entrance Reynolds number is 8×10⁴ and cross-flow ratio is 0.5 and 1. A smooth channel was also investigated to get a reference for calculation. Numerical results reveal that when both the entrance Reynolds number and cross-flow ratio are constant, with an increase in cross-flow Mach number from 0.2 to 0.7, the range of inverse flow in the effusion hole is decreased and thus the flow resistance is weakened. Besides, the local heat transfer near the effusion holes is weakened with increase of the cross-flow Mach numbers. Additionally, the cross-flow Mach number, under the low cross-flow ratio, has a stronger effect on the heat transfer on cooling channel wall in comparison with the high cross-flow ratio.