基于一方程转捩模型的狭缝冲击射流传热数值模拟

Numerical simulation of slot jet impingement heat transfer based on one-equation intermittency transition model

  • 摘要:
      目的  由于冲击射流现象涉及层流-湍流转捩、极强的逆压梯度和分离流问题,导致传统湍流模型无法对其准确预测。为了研究湍流模型在多种条件下的鲁棒性,
      方法  采用基于转捩机理的一方程转捩模型,预测以局部努塞尔数(Nu)来衡量的狭缝冲击射流的传热特征。在冲击距离范围为4 ≤ H/B ≤ 9.2时,对稳态和脉动冲击射流传热问题进行研究。
      结果  结果表明,在H/B=4时,一方程转捩模型准确地捕捉了受转捩影响的局部努塞尔数第2峰值的大小和位置;在H/B=9.2时,该模型避免了大多数传统雷诺时均模型(RANS)中出现的假第2峰值,获得了更符合实验结果的传热分布规律。
      结论  在较大的H/B范围内,一方程转捩模型能够准确预测狭缝冲击射流的传热分布,表现出良好的鲁棒性。

     

    Abstract:
      Objectives  Since the jet impingement phenomena involves the problems of laminar-turbulence transition process, strong adverse pressure gradient and separated fluid, it is difficult to predict the phenomenon by using the traditional turbulence models. Therefore, it makes great sense to studying the robustness of the turbulence models under different conditions.
      Methods  The one-equation transition model based on the laminar-transition theory was applied for the numerical simulation of heat transfer of slot jet impinging flows. The numerical model accurately predicted the heat transfer characteristics measured with the local Nusselt number (Nu), where the cases with the range of nozzle-plate spacing ≤ H/B ≤ 9.2 for steady and pulsating jet impingement heat transfer are studied.
      Results  The numerical results show that for the case of H/B=4, the one-equation transition model accurately captures the value and position of secondary Nusselt number peak affected by the transition; and for the case of H/B=9.2, the one-equation transition model does not have the false secondary peak which occurs in the most of traditional Reynolds-Average Navier-Stokes (RANS) turbulence models and obtains good Nusselt number distribution comparing with the experimental data.
      Conclusions  In general, the one-equation transition model is able to predict the heat transfer for steady and pulsating slot jet impinging flows accurately and has shown a good robust characteristic for large range of nozzle-plate spacing.

     

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