Effect of aspect ratio on flow characteristics in a confined channel with staggered jet array impingement

Research on better understanding of impingement cooling in confined channel was conducted. The main purposes of this study were to gain greater insight into the structure of impingement jet flow within a confined passage and to understand more the effect of cross flow on the structure of impingement jet flow as well as to get better understanding on the distribution of aerodynamic parameters along the passage. Experimental results were presented to describe the effect of aspect ratio on flow behavor in a confined channel with twelve staggered jet holes and a larger exit hole. The variation of mass flux ratios, distribution of static pressure along the passage and change of discharge coefficient in the holes were also studied. The experimental data showed that the aspect ratio dominated the flow characteristics in the passage and exit hole, but its effect decreased in larger channel section area. The increase of aspect ratio weakened the cross flow in the passage as well as extended the distance of jets to the target wall, which leaded to the ineffective impingement in the downstream region. With aspect ratio increasing, the mass flux distribution became evener and the decline of static pressure became gentle along the passage as well as the outflow condition was improved.