通道高度对受限长通道流动特性的影响

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

为更好地掌握涡轮叶片错排射流冲击受限长通道内的流动结构,了解横流对射流作用的影响,获取沿流动方向通道内的流动特性,对包含12个射流孔和1个出流孔的受限通道流场进行了详细的测量,着重研究受限通道和出流孔内的流动特性,同时获得沿通道密流比、侧壁静压以及孔流量系数的变化规律。实验结果表明:通道高度主导着通道和出流孔内的流动特性,但其影响随着通道高度的进一步增加而减弱;通道高度的增加削弱了横流强度,但也增加了射流流程,使其在下游位置无法对靶面形成有效冲击;随通道高度的增加,沿通道流量分配趋于均匀,密流比呈线性分布,沿程压降趋缓,出流孔流量系数提高。

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 dicreased 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.