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利用流动稳定性理论中一般共振三波的概念,对有压力梯度湍流边界层的相干结构进行研究。通过计算得出顺压梯度能够抑制相干结构的产生和发展,而逆压梯度对之有激励和促进的作用。此外,与无压力梯度相比,相干结构的尺度、形状以及传播速度等都已改变,理论分析所得变化趋势与实验结果相一致。计算流向涡对无量纲环量差概率密度分布曲线发现逆压梯度下流向涡对较无压梯度更趋于对称。
Using the concept of general resonance three waves in flow stability theory, the coherent structure of turbulent boundary layer with pressure gradient is studied. Computation shows that the pressure gradient can suppress the generation and development of coherent structure, while the pressure gradient has the incentive and promotion effect. In addition, compared with the non-pressure gradient, the size, shape and propagation velocity of the coherent structure have been changed. The trend of the theoretical analysis is consistent with the experimental results. Calculating the distribution of the vortex flow versus the non-dimensional volumetric difference in the probability density distribution curve shows that the vortex flow in the reverse pressure gradient tends to be more symmetrical than the non-pressure gradient.