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狹縫射流沖擊柱狀凸形表面流動換熱特性

Flow and heat transfer characteristics of slot jet impingement to a cylindrical convex surface

  • 摘要: 采用數值方法研究了狹縫射流沖擊柱狀凸形表面的流動換熱特性,通過四種湍流模型計算結果與實驗數據對比,確定了湍流模型適用性.以壓力梯度分布為依據,重點分析了狹縫射流沿柱狀凸形表面的流動結構和邊界層分離特點及柱狀凸形表面的強化換熱特性.結果表明:RNG k-ε和Realizable k-ε模型具有預測適應性;狹縫射流沖擊至柱狀凸形表面,氣體沿表面運動,速度降低,并在流動下游發生邊界層分離;量綱一的逆壓梯度隨量綱一的曲率半徑(D/B)的減小而增大,使得邊界層分離更早出現;駐點區域換熱Nu隨量綱一的曲率半徑(D/B)的減小而獲得增強,但流動進入下游后,D/B對換熱基本無影響;壓力梯度是影響狹縫射流沖擊柱狀凸形表面換熱分布的重要因素.

     

    Abstract: The flow and heat transfer characteristics of slot jet impingement to a cylindrical convex surface were investigated by the numerical method.Suitable turbulence models were determined by comparing experimental data with the numerical results of four turbulence models.The flow structure,boundary layer separation and wall heat transfer enhancement characteristics of slot jet impingement to a cylindrical convex surface were discussed on the basis of the pressure gradient distribution.The results show that RNG k-ε and Realizable k-ε models are suitable to predict.The slot jet impinges to a cylindrical convex surface,the gas flows along the convex surface,the velocity decreases and the boundary layer separation appears downstream.The dimensionless adverse pressure gradient increases with the dimensionless radius of curvature(D/B) decreasing,leading to an earlier boundary layer separation.Nu in the stagnation region can be enhanced by decreasing D/B.However D/B has almost no effect on heat transfer in the downstream flow.The pressure gradient is a key factor in affecting the heat transfer distribution in slot jet impingement to a cylindrical convex surface.

     

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