Two kinds of lamilloy models with different percentages of film hole opening were experimentally studied at the Reynolds numbers of 1×104-6×104

target surface

impingement surface and pressure coefficients of pinfins surface

local and total loss coefficients of impingement jet

arounding flow

effusion were experimented to explore the mechanism of flow loss. Results showed that

the pressure distributions were characterized by the second maximum value because of the transition from an accelerating stagnation region flow to a decelerating wall jet. The low pressure coefficients on the target and impingement surfaces were caused by the sink of two jets and the backflow

respectively. The pressure coefficients distributions on two rows of pinfins relatively far away from the impingement hole were significantly affected by Reynolds numbers. At the Reynolds number less than or equal to 3×104

the pressure distributions were similar with flow across cylinder. At the Reynolds number greater than or equal to 4×104

it also had characteristics of backflow. The effusion loss coefficients were biggest

the impingement jet loss coefficients were smallest and the arounding flow loss coefficients were moderate. As the percentages of opening decreased one half

the effusion loss coefficients of film holes increased at least 4 times while the loss coefficients of impingement jet loss and arounding flow had slight changes.