Abstract

The current paper has focused on finding the optimum cavity properties to enhance the mixing phenomenon and combustion processes in supersonic flow using Computational Fluid Dynamics (CFD) ANSYS Fluent. Various models have has been modeled with different values of offset ratios (OR) and aft ramp angles (ϴ) while keeping the length-to-depth ratio constant. All cavity flows have taken open type, i.e. length-to-depth ratio <10. A cavity with a width of 1mm was used for hydrogen fuel injection over and done with transverse slot nozzle into a supersonic air stream flow with Mach number 3.75. The free stream pressure, temperature and Reynolds number were 1.2MPa, 299K, and 2.07x107 respectively. The cavity provides a stable flame, rapid mixing of fuel and oxidizer and minimizes the total pressure losses thus making cavity a promising flame-holder technique. Fromorm a viewpoint of combustion efficiency and total pressure loss the cavity influence is discussed and compared with the without cavity model. When compared with the without cavity model the mixing properties and combustion processes were enhanced. Both the total pressure loss and combustion efficiency are increaseds with increasing aft ramp angle ϴ. Whereas, an increment in OR has the adverse effect on both because of less obstruction generated on the supersonic flow field. Higher ramp angle caused higher eddy-viscous turbulent flow and wall drag which increased the total pressure losses.

Authors and Affiliations