EFFECT OF SUCTION ON THE STABILITY OF SUPERSONIC BOUNDARY-LAYERS .1. 2ND-MODE WAVES

The effect of suction on the second (Mack) mode of instability in supersonic and hypersonic two-dimensional boundary layers is investigated. The results show that suction has a stabilizing effect on these waves; it reduces the peak amplification and shifts it toward a higher frequency. In the presence of suction, the most amplified Mack mode remains two-dimensional. The effectiveness of suction in stabilizing Mack waves decreases as the Mach number increases. Variations of the growth rates of the most amplified Mack mode and the corresponding frequencies and wave numbers with mass flux are found to be almost linear. The frequencies and wave numbers corresponding to the most amplified Mack mode increase by increasing the suction level.