Evolution of nonlinear processes in a hypersonic boundary layer on a sharp cone

Abstract

Nonlinear processes in a hypersonic boundary layer on a sharp cone are considered using the bicoherence method. The experiments are performed for a Mach number M∞ = 5.95 with introduction of artificial wave packets at the frequency of the second mode. It is shown that the basic mechanism of nonlinear interaction at the location of the maximum r.m.s. voltage fluctuation is the subharmonic resonance; all nonlinear interactions in the maximum r.m.s. voltage fluctuation layer are related to the second mode of disturbances; nonlinear processes above and below that layer are much more intense than those in it. The effect of artificial disturbances on nonlinear interactions in the boundary layer is shown to be insignificant.

Numerical Investigation of Laminar-Turbulent Transition in a Cone Boundary Layer at Mach 6

“…However, from these experiments it was still not clear what role the second-mode waves play in the nonlinear stages of the transition process. In recent experiments, Shiplyuk et al (2003) and Bountin et al (2008) investigated transition in a sharp cone boundary layer at Mach 6 in a conventional tunnel. They perturbed the boundary layer using glow discharge actuator as a harmonic point source.…”

“…In recent experiments, Shiplyuk et al (2003) and Bountin et al (2008) investigated transition in a sharp cone boundary layer at Mach 6 in a conventional noisy tunnel. They perturbed the boundary layer using glow discharge actuator as a harmonic point source.…”

“…Therefore, an isothermal wall is the most appropriate boundary condition for the simulations (Schneider, 2009). In conventional tunnels, however, the run time is much longer and sometimes the cone model is preheated to bring it close to adiabatic wall temperature conditions (Bountin et al, 2008). Hence, two wall boundary conditions are used in the simulations to compare and study the effect of wall temperature under the BAM6QT flow conditions.…”

Анализ Развития Возмущений В Гиперзвуковом Пограничном Слое За Волнистой Поверхностью

“…приводит к росту гармоники волн второй моды. Данный тип взаимодействия является типичным в гиперзвуковом пограничном слое [7]. Бурное про-явление нелинейных процессов говорит о начале турбулизации потока.…”

Growth and breakdown of wave packets in a high-speed boundary layer

“…In the region between the two original maxima (y/δ = 0.2-0.4), the fundamental structure angle has reached values up to 160 • and gradually the angle close to the y/δ = 0.7 maximum increases as the folding over of the wave structures becomes more pronounced. The structure of the wave packet then quickly becomes three-dimensional due to developing nonlinear processes (Bountin, Shiplyuk & Maslov 2008), which the used Schlieren technique is not able to visualize, so that the packet becomes less distinct. At high enthalpy, LWH investigated the laminar boundary layer and observed the second-mode wave packets at frequencies of approximately 600 kHz, phase velocity u phase ≈ 3680-3810 m s −1 (or u phase /u e = 0.85-0.88), with a very weak first harmonic at 1200 kHz.…”