Effect of the Wave Structure of the Flow in a Supersonic Combustor on Ignition and Flame Stabilization

• Published in: Combustion, explosion, and shock waves Vol. 54; no. 6; pp. 629 - 641
• Main Authors: Goldfeld, M. A., Zakharova, Yu. V., Fedorov, A. V., Fedorova, N. N.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2018; Springer Nature B.V
• Subjects: Aerodynamics; Chemical reactions; Classical and Continuum Physics; Classical Mechanics; Combustion chambers; Computational fluid dynamics; Computer simulation; Configurations; Control; Dynamical Systems; Engineering; Enthalpy; Entrances; Flight conditions; Flow control; Fluid flow; Ignition; Mach number; Organic chemistry; Physical Chemistry; Physics; Physics and Astronomy; Pressure distribution; Reaction kinetics; Reynolds number; Stabilization; Stress concentration; Supersonic flow; Turbulence models; Vibration; Wind tunnel testing; Wind tunnels; shock wave; supersonic flow; premixed mixture; combustor; turbulence; expansion wave; ignition
• ISSN: 0010-5082; 1573-8345
• DOI: 10.1134/S0010508218060011

Results of numerical and experimental investigations of a high-velocity flow in a plane channel with sudden expansion in the form of a backward-facing step, which is used for flame stabilization in a supersonic flow, are presented. The experiments are performed in the IT-302M high-enthalpy short-duration wind tunnel under the following test conditions: Mach number at the combustor entrance 2.8, Reynolds number 30 · 10 6 m −1 , and total temperature T 0 = 2000 K, i.e., close to flight conditions at M = 6. The numerical simulations are performed by solving full unsteady Reynolds-averaged Navier–Stokes equations supplemented with the k – ω SST turbulence model and a system of chemical kinetics including 38 forward and backward reactions of combustion of a hydrogen–air mixture. Three configurations of the backward-facing step are considered: straight step without preliminary actions on the flow, with preliminary compression, and with preliminary expansion of the flow. It is demonstrated that the backward-facing step configuration exerts a significant effect on the separation region size, pressure distribution, and temperature in the channel behind the step, which are the parameters determining self-ignition of the mixture. The computed results show that preliminary compression of the flow creates conditions for effective ignition of the mixture. As a result, it is possible to obtain ignition of a premixed hydrogen–air mixture and its stable combustion over the entire channel height.