The links between coherent structures in the shear layer of an isothermal Mach 2 jet and steepened Mach waves just outside the jet are investigated using large-eddy simulation. Conditional averages triggered by the detection of high-intensity pressure peaks on a conical surface near the jet flow are computed. Averages obtained for peaks of different intensities are presented to identify the factors favoring the steepened aspect of the waves, which are not likely due to nonlinear propagation effects given the surface radial position. The Mach waves just outside the jet are shown to be correlated with coherent structures in the supersonic side of the mixing layers. Their steepened aspect is found to increase with their intensity. The variations of the wave properties with the convection speed, strength, and geometrical shape of the mixing layer structures are then discussed. These properties do not depend much on the convection speed but are closely related to the two other parameters. The wave intensity and steepened aspect increase because the shear-layer structures are stronger, but also because they are more inclined relative to the jet direction. In the latter case, the asymmetric shape of the structure appears to promote the formation of positively skewed Mach waves.

使用大涡模拟研究了等温马赫2射流剪切层中的相干结构与射流外的陡峭马赫波之间的联系。计算通过检测喷射流附近的锥形表面上的高强度压力峰值触发的条件平均值。给出了不同强度峰的平均值，以识别有利于波的陡峭方面的因素，由于给定表面径向位置的非线性传播效应，这不太可能。恰好在射流外部的马赫波与混合层超音速一侧的相干结构相关。发现其陡峭的外观随其强度增加。波特性随对流速度，强度，然后讨论混合层结构的几何形状。这些特性在很大程度上不取决于对流速度，但与其他两个参数密切相关。由于剪切层结构更坚固，而且还因为它们相对于射流方向更倾斜，因此波强度和变陡的方面会增加。在后一种情况下，结构的不对称形状似乎促进了正偏马赫波的形成。