A Numerical Study Of The Evolution Of 2-D Disturbance In Supersonic Sharp Cone Boundary Layer With Zero Angle Of Attrack

The study of the mechanism of transition of compressible flow is of significant importance both from the theoretical and practical point of view. There are many problems with curvature in practical engineering. Compressible flow passing a sharp cone with zero angle of attrack is a typical boundary layer problem with curvature. In this paper, we study the evolution of disturbances of compressible flow passing a sharp cone with zero angle of attrack by using DNS.In this paper, a new method was developed to calculate the steady boundary layer flow passing the sharp cone. The full flow-field was divided into two parts, one is non-viscous area, where solution could be got by solving the Eular equation under the sphere coordinate axis, the other one is viscous area close to the cone, where the solution could be got by solving the N-S equation, with upper boundary condition adopted the non-viscous solution. In this way, we could not only get the exact solution of the full flow-field, but also save time in calculation.Basing on the steady flow, the evolution of 2-D T-S disturbances in supersonic sharp cone boundary layers with the oncoming flow of Mach number 5.29 and semi-angle 10°was investigated by direct numerical simulation (DNS). The main contents and conclusions are as follows:1. Although the normal velocity value in the sharp cone boundary layer was not small, when a small amplitude disturbance was introduced at the entrance of the computational domain, the amplitude and phase of disturbance wave during the evolution would agree well with the results obtained by the linear stability theory (LST), which supposed the flow was parallel. This means although the normal velocity is not small in the basic flow of the supersonic compressible sharp cone boundary layer, for small semi-angle, LST can still be used.2. When the value of the disturbances amplitude enlarged, the harmonic waves occured with the effect of nonlinear. The amplified rate of the disturbance was far less than the LST's, and the profile of the disturbances was different from the small one.3. When the amplitude grows upto about 0.12, shocklets would generate. The velocity of shocklets and the distance between two near shocklets are the...