Control of oblique breakdown in a supersonic boundary layer employing a local cooling strip

Abstract

Oblique breakdown in a Mach 2.0 supersonic boundary layer controlled by a local cooling strip with a temperature jump is investigated using direct numerical simulations and linear stability theory. The effect of temperature on the stability of the fundamental oblique waves is first studied by linear stability theory. It is shown that the growth rate of fundamental oblique waves will decrease monotonically as the temperature decreases. However, the results of the direct numerical simulations indicate that transition reversal will occur as the growth rate of the fundamental oblique waves of cooled case becomes faster compared with that of baseline case downstream of the cooling strip. When the cooling strip is in the linear region, the transition is delayed due to the suppression effect of the cooling strip on the fundamental oblique waves. When the cooling strip is located in the early nonlinear region, the fundamental oblique waves will be suppressed by higher spanwise wavenumber steady modes generated by the mutual and self-interaction between the fundamental oblique waves and harmonic modes, which is first called the self-suppression effect (SSE) in the present study. Further research indicated that the meanflow distortion generated by steady modes plays an important role in the SSE. Compared with the stabilization effect of the cooling strip, the SSE is more effective. Moreover, the SSE might provide a new idea on the instability control, as it is observed that the SSE works three times leading to the growth rate of fundamental oblique waves slowing down at three different regions, respectively.

Interactions between oblique second mode and oblique waves in a high-speed boundary layer

“…Thus, the utilization of the six reserved modes in the computation is considered accurate. The validation of the LST solver can be found in Zhou et al (2022a).…”

“…The Navier–Stokes equations are the governing equations for the DNS in this study, which are in the form of The conservative variables , convective flux vectors and viscous flux vectors in the DNS are described in more detail in Zhou et al. (2022 a ), and Re is the Reynolds number. These simulations are carried out using the OpenCFD code developed by Li et al.…”

“…The conservative variables Q, convective flux vectors F c,j and viscous flux vectors F v,j in the DNS are described in more detail in Zhou et al (2022a), and Re is the Reynolds number. These simulations are carried out using the OpenCFD code developed by Li et al (2010b), which has been used to study high-speed boundary layer transitions (Li, Fu & Ma 2010a) and turbulent flows (Li et al 2019).…”

Modelling and shock control for a V-shaped blunt leading edge

“…2022; Zhou et al. 2022). In particular, shock control methods can effectively reduce the adverse effect caused by SWBLI (Ashill, Fulker & Hackett 2005).…”

“…However, the purpose of exploring the flow mechanism and predicting heat flux peaks is for better control and protection in aircraft design (Liu et al 2022;Zhou et al 2022). In particular, shock control methods can effectively reduce the adverse effect caused by SWBLI (Ashill, Fulker & Hackett 2005).…”