Executive Summary : | Looking at the significant potential of scramjet engines, researchers have focused on different fuel injection systems with cavity flame holders in scramjet combustors to improve the combustion efficiency of scramjet engines. Among the various fuel injection techniques used in scramjet combustors, wall injection and strut base injection are the most well-liked. In the case of wall injection, a bow shock is generated, which enhances the combustion efficiency by improving the mixing of air and fuel. However, it also reduces trust force due to increases in pressure loss inside the combustor. Whereas, in strut base injection, significant improvement in the thrust force due to less reduction in the pressure loss is observed, along with a slight decrease in combustion efficiency compared with wall injection. The reduction in the combustion efficiency of a scramjet combustor with strut base injection is mainly because of the inadequacy of mixing of air and fuel. This inadequacy of mixing in scramjet combustor with strut base injection is due to insufficient fuel penetration in a supersonic air stream. Hence, this study has proposed a novel twin strut injection system to counter improper mixing associated with strut base injection. The novel strut will be modeled in such a manner that hydrogen fuel will be injected at some optimum angle into the supersonic air stream. On using twin struts, the required quantity of fuel to be injected will be divided between both struts. Consequently, each strut will inject a smaller quantity of hydrogen fuel. In addition, the scramjet combustor with the proposed novel twin strut injection will also have three air streams instead of two, which will ultimately improve the mixing of air and fuel. However, it is essential to determine the optimum injection angle (?) and strut gap (G) for efficient mixing of air and fuel, which will eventually improve the combustion performance of the combustor. In view of the above discussion, the research proposes to numerically investigate the effect of injection angle (?) and strut gap (G) on fluid flow and combustion performance of the combustor with novel twin strut injection system through finite volume technique for solving the discretized Reynolds-averaged Navier-Stokes equations using the standard K-? turbulence and eddy dissipation models. Furthermore, the research also proposes to develop an empirical relationship between injection angle (?), strut gap (G) and combustion efficiency of the combustor using the results from the numerical analysis. At last, the research proposes to optimize the empirical relationship for determining the optimal injection angle (?) and strut gap (G) for maximum combustion efficiency of the combustor with the novel twin strut injection system. |