Numerical modelling of supersonic boundary-layer receptivity to solid particulates

Abstract

Atmospheric particulates may be a major source of boundary-layer instabilities leading to laminar–turbulent transition on aerodynamically smooth bodies flying at supersonic speeds. Particulates penetrating into the boundary-layer flow can excite wavepackets of the first- and/or second-mode instability. The packets grow downstream, reach the threshold amplitude and ultimately break down to turbulent spots. A numerical model is developed to simulate excitation of unstable wavepackets by spherical solid particulates. As an example, computations are carried out for a $14^{\circ }$ half-angle sharp wedge flying at an altitude of 20 km, Mach number 4 and zero angle of attack. The numerical results agree satisfactorily with the theory developed by Fedorov (J. Fluid Mech., vol. 737, 2013, pp. 105–131). The numerical model opens up an opportunity to investigate receptivity to particulates for practical supersonic and hypersonic configurations such as blunt bodies of revolution.

Numerical Simulation of Disturbance Evolution in the Supersonic Boundary Layer over an Expansion Corner

“…In accordance with the linear stability theory for the flat-plate boundary layer, for the flow parameters under consideration there exists only one unstable mode, namely, the first mode according to Mack's terminology [18,19]. The first-mode disturbances are oblique waves propagating with the front inclination As can be seen in Figs.…”

Three-dimensional wave packet in a Mach 6 boundary layer on a flared cone

“…A theoretical model developed by Fedorov (2013) for one of the disturbance sources identified by Bushnell (1990) showed that solid particulates can excite instability waves in the high-speed boundary layer upon impact on the vehicle surface. Building on the theoretical model by Fedorov (2013), direct numerical simulations (DNS) by Chuvakhov, Fedorov & Obraz (2019) showed that particle impact generates a wave packet that may ultimately lead to transition on a 14 • half-angle wedge at M = 4. That investigation has shown that wave packets are not only a model for 'natural' transition (initiating the breakdown process by broadband disturbances), but that the investigation of a wave packet in high-speed boundary layers also has relevance as it can be considered to be a model of disturbances that are generated in the boundary layer by particle impact.…”

Eulerian–Lagrangian direct numerical simulation of preferential accumulation of inertial particles in a compressible turbulent boundary layer

“…For example, compressible turbulent boundary layers (CTBLs) laden with particles are commonly encountered in the mixing of fuels in scramjets (Urzay 2018), flights in sandy or rainy atmospheres (Fedorov 2013) and exhaust gas from rocket engines (Nagata et al 2018). Particles are essential for triggering compressible boundary layer transition processes (Chuvakhov, Fedorov & Obraz 2019), affecting flight performance (Li & Bai 2015), and controlling the temperature and noise of exhaust gas flow (Ignatius, Sathiyavageeswaran & Chakravarthy 2014). Furthermore, particle response in CTBLs is crucial in the tracer-particle-based experimental measurement of high-speed boundary layer flows (Williams et al 2018), in which strong particle lag effects are exhibited on the experimental results of Reynolds stress (Lowe, Byun & Simpson 2014).…”

“…2018). Particles are essential for triggering compressible boundary layer transition processes (Chuvakhov, Fedorov & Obraz 2019), affecting flight performance (Li & Bai 2015), and controlling the temperature and noise of exhaust gas flow (Ignatius, Sathiyavageeswaran & Chakravarthy 2014). Furthermore, particle response in CTBLs is crucial in the tracer-particle-based experimental measurement of high-speed boundary layer flows (Williams et al .…”