Effect of hump shape on boundary layer instability is investigated for incompressible, supersonic, and hypersonic speed regimes. Flat-plate boundary layers over a two-dimensional smooth hump of five different geometries are considered. The linear evolution of instability waves is analyzed by using the parabolized stability equation. The resulting growth rate and N-factor are compared for several frequencies. The destabilization effect of the hump is evaluated in terms of the change in N-factor. The overall influence of the hump is also assessed by comparisons of N-factor envelopes and predicted transition locations based on e^N-method. Results show that the destabilization effect is the greatest for the incompressible case. The degree of destabilization appears to depend not only on the hump area but also the other geometric parameters. The variation of the predicted transition Reynolds number depending on the hump shape is pronounced only in a certain range of hump heights. Although the supersonic boundary layer also exhibits similar characteristics, the effectiveness of hump is rather low, and relatively insensitive to the hump shape. In the case of the hypersonic boundary layer, the hump exhibits either destabilization or stabilization effect, depending on the relative location of a synchronization point. The degree of destabilization depends strongly on the both hump area and frequency. Either the transition delay or early transition could be predicted depending on the hump location and critical N-factor value employed. Unlike the incompressible case, the dependency on the hump shape is not confined to a certain range of hump heights.

对于不可压缩，超音速和高音速速度状态，研究了峰形对边界层不稳定性的影响。考虑了五个不同几何形状的二维平滑驼峰上的平板边界层。利用抛物线稳定方程分析了不稳定波的线性演化。比较了几个频率的结果增长率和N因子。根据N因子的变化评估驼峰的去稳定作用。通过比较N因子包络和基于e ^N的预测过渡位置，还可以评估驼峰的总体影响-方法。结果表明，对于不可压缩的情况，去稳定作用最大。不稳定程度似乎不仅取决于驼峰区域，而且还取决于其他几何参数。仅在一定的驼峰高度范围内，才根据驼峰的形状预测转变雷诺数的变化。尽管超音速边界层也表现出相似的特性，但驼峰的有效性相当低，并且对驼峰形状相对不敏感。在高超声速边界层的情况下，取决于同步点的相对位置，驼峰要么表现出不稳定作用，要么表现出稳定作用。不稳定程度在很大程度上取决于驼峰面积和频率。使用N因子值。与不可压缩的情况不同，对驼峰形状的依赖性不限于驼峰高度的特定范围。