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中文核心期刊

压力梯度对湍流逆梯度输运的影响

Effects of pressure-gradient on turbulent counter-gradient transport

  • 摘要: 用雷诺应力封闭模式(RSM) 和k-e模式对底部放置了对称翼型的完全发展的非对称槽道流动进行了数值模拟研究. 工程实际中有压力梯度变化的流动是较常见的,这些压力梯度会导致较强的湍流结构的变化,从而影响湍流的扩散和传输过程. 用数值计算方法从压力梯度对湍流逆输运现象的影响角度展开研究,以期了解并揭示湍流逆输运现象的物理机理. 由计算结果可以看出,RSM模式能够较k-e模式更好地反映逆梯度输运(CGT)现象;逆梯度输运现象的出现比湍动能负产生率更为普遍;压力梯度的变化对湍动能负产生率区域和CGT区域的影响是有规律的,顺压梯度时,湍动能负产生率区域逐渐缩小,至压力梯度为零时消失,此时CGT区域从无到有,呈先增大后缩小的趋势;逆压梯度时,湍动能负产生率区域不复存在,此时CGT区域从有到无,也是呈先增大后缩小的趋势,并最终消失;CGT区域内雷诺应力与平均速度梯度呈非线性关系

     

    Abstract: By using Reynolds Stress Closure Model (RSM) and k-e Model, the turbulent field of wing flow is numericallysimulated. In most practical situations, flows with changing pressuregradient are familiar, these pressure gradients may induce strongmodifications of turbulent structure, accordingly, affect the diffusion andtransportation process of turbulence. The effects of pressure gradient oncounter-gradient transport phenomena are studied. The computational resultsshow that RSM model can describe the CGT phenomena while k-e model cannot. Negative turbulent energy production appears in the result ofRSM, but it behaves differently with CGT: it gradually shrinks until theposition of the wing central part is reached, where it vanishes; while theCGT region exists all along. This fact shows that CGT phenomena is moregeneral than negative turbulent energy production. The pressure gradienttakes an important effect on the region of negative turbulent energyproduction and counter-gradient transport. In the CGT region, the relationbetween turbulent Reynolds stress and mean velocity gradient is nonlinear.

     

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