Numerical Simulation of Wall Injection with Cavity in Supersonic Flows of Scramjet Combustion
K.M. Pandey1, S.K. Reddy K.K.2
1Dr. K M Pandey, is currently working as Professor, Department of Mechanical Engineering, NIT Silchar, Assam, India.
2S K Reddy K.K. has done M.Tech in Thermal Engineering from Department of Mechanical Engineering, NIT silchar , Assam , India.

Manuscript received on February 03, 2012. | Revised Manuscript received on February 10, 2012. | Manuscript published on March 05, 2012. | PP: 142-150 | Volume-2 Issue-1, March 2012. | Retrieval Number: A0402012112/2012©BEIESP
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Abstract: A supersonic combustion ramjet engine (scramjet) is one of the most promising air-breathing propulsive systems for future hypersonic vehicles, and it has drawn the attention of an ever increasing number of researchers. This work involves an application of computational fluid dynamics to a problem associated with the flow in the combustor region of a scramjet. A cavity wall injector is an integrated fuel injection approach, and it is a new concept for flame holding and stabilization in supersonic combustors. The presence of a cavity on an aerodynamic surface could have a large impact on the air flow surrounding it, and this makes a large difference to the performance of the engine, namely it may improve the combustion efficiency and increase the drag force. The objective of the work was to design the four wall injector model with cavity using gambit, study the combustion processes of airfuel (h2) mixture for the wall injector models with inlet air at Mach number 2 and inlet fuel at Mach number 2 and compare the performance of the different wall injector models. There are several key issues that must be considered in the design of an efficient fuel injector. Of particular importance are the total pressure losses created by the injector and the injection processes that must be minimized since the losses reduce the thrust of the engine. In this analysis, the two-dimensional coupled implicit Reynolds averaged Navier-Stokes (RANS) equations, the standard k-ε Turbulence model, sst-kω Turbulence and the eddy-dissipation reaction model have been employed to investigate the flow field in a hydrogen-fuelled scramjet combustor with a cavity design and to analyze the combustion processes. Numerical results are obtained with the fluent solving sst-kω Turbulence model to have the best results of all models. The grid independent test was also carried out. The profiles of static pressure, static temperature, and two components of velocity and mole fraction of hydrogen at various locations of the flow field are presented. Computed values using sst-kω turbulence model are found to have good overall agreement with results obtained from literature reviews and some discrepancies were observed for static pressure and static temperature in the vicinity of the jets due to unsteadiness in the shock system.
Keywords: Scramjet engine, Mach number 2, RANS Equations, Turbulence model.