| The study of the mechanism of transition of compressible flow is of significant importance both from the theoretical and practical point of view. In this paper, N-S equations were solved with high precision compact scheme by using DNS. The T-S wave was introduced at the inlet of 2-D compressible supersonic boundary layer with pressure gradient. We studied the evolution of the disturbance, whether or not the shocklets could appear and the relation between the appearance of shocklets and amplitude of disturbance. The main contents and conclusions are as follows:When the T-S wave is introduced at the inlet, if the amplitude is smaller than 0.05, the curve of amplitude of the disturbance is agree with the result of linear stability theory. But the growth of the amplitude of disturbance both in favorable pressure gradient and adverse pressure gradient is smaller than that in zero pressure gradient. And the greater the pressure gradient, the smaller the amplitude grows. When the pressure gradient is great enough, the growth of the amplitude will become smaller.In the flow filed with different pressure gradient, for the profile of the same Mach number, the greater the favorable pressure gradient, the higher the frequency of the most unstable wave and the smaller the peak amplitude. For different adverse pressure gradient, the greater the adverse gradient the lower the frequency and the greater the peak amplitude. The pressure gradient has influence on the neutral curve. The favorable pressure gradient makes it higher and the adverse gradient makes it lower.When the amplitude of the disturbance is great enough, the non-linear effect is reinforcing. Compared to the result of zero pressure gradient, the adverse pressure gradient makes the amplitude of the disturbance greater and the favorable pressure gradient has the opposite effect. When the amplitude of the disturbance is greater than 0.1, in the flows with all kinds of pressure gradient, the shocklets would appear.
|
PDF Full Text Request