孔-肋相对位置对通道各壁面换热影响

IInfluence of the Relative Positions of Holes and Ribs on the Heat Exchange Through Various Wall Surfaces in the Passages

数值模拟了肋和气膜孔的相对位置对矩形通道4个壁面换热特性的影响,重点分析了通道4个壁面换热系数差别以及3种气膜孔位置换热。计算结果和实验数据吻合较好。结果表明:气膜孔位置对同时带肋和气膜孔的下壁面影响最大,孔在肋间上游换热最好,孔在肋中间换热次之,孔在肋间下游换热最差,气膜孔位置对光滑的左右壁面换热影响较小,对只带肋的上壁面几乎没有影响。肋的扰流和气膜孔抽吸使通道下壁面换热系数增幅最大,左右壁面次之,上壁面最小。沿着流动方向,肋扰流和气膜孔出流共同作用导致带肋壁面换热增强因子先增大后减小,光滑壁面换热增强因子先保持不变后减小。

Numerically simulated was the influence of the relative positions of holes and ribs on the heat exchange characteristics of the four wall surfaces of a rectangular passage.As an emphasis,analyzed were the difference of the heat exchange coefficients of the four wall surfaces and influence of the positions of the three types of air film holes on the heat exchange.The calculation results are in relatively good agreement with the test ones.It has been found that the positions of the air film holes have a biggest influence on the lower wall surface concurrently provided with ribs and air film holes.The holes are located at the upstream between ribs will result in the best heat exchange,they are located in the middle of the ribs comes next and they are placed at the downstream between ribs will lead to the worst heat exchange.The positions of the air film holes have a relatively small influence on the heat exchange through the smooth wall surfaces on both left and right and have almost no influence on the upper wall surface provided with only ribs.The turbulent flow around ribs and the suction from the air film holes make the heat exchange coefficient of the lower wall surface have a biggest increase followed by that of the wall surfaces on both left and right and the upper wall surface.Along the flow direction,the joint action of the turbulent flow around the ribs and flow outgoing from the air film holes will force the heat exchange intensification factor of the wall surfaces with ribs to first increase and then decrease while the smooth surface heat exchange intensification factor of the smooth wall surfaces will first keep constant and then decrease.