N umerical Investigation of Hydrogen-fuelled Scramjet Combustor with Cavity Flame Holder

Abstract

Reacting flow field of a cavity-based hydrogen-fuelled supersonic combustion ramjet (scramjet) combustor has been explored numerically. 3-D RANS equations are solved alongwith k-ε turbulence model and infinitely fast rate kinetics for combustion. The flow field inside the flame holding cavity and its effect on the mixing and reaction are explored in detail by performing simulations of two different combustors (with and without cavities) for which elaborate surface pressure measurements are available for reacting and non-reacting flows. Simulations capture all the finer details of the flow field and good match between computed surface pressures experimental values for different equivalence ratios forms the basis of further analysis. The cavity of the combustor behaves as an open cavity for both non-reacting and reacting flow-even though the flow patterns inside the cavity are quite different for both the cases. Flame-holding cavities are seen to augment mixing and reaction in small sized combustors.

Enhancing mixing features in supersonic flow through geometric correction of the cavity depth relative to the height of the combustion chamber

“…In this case, strong adverse gradient is developed along the cavity floor due to pressure distribution. Usually open cavities and close cavities are used as flame holders and mixing enhancer, respectively [8].…”