Fuel/Air Mixing Characteristics of Strut Injections for Scramjet Combustor Applications

Numerical studies were performed to determine the fuel/air mixing characteristics of several strut fuel-injection schemes for possible use in round scramjet-combustor applications. Gaseous ethylene was used as the fuel injectant. A total of fourteen strut-injection schemes were conducted with a Mach 2 inflow condition in a rectangular flow path. In addition, the StrutE-s-2 design was simulated in a Mach 3 flow to provide a better understanding of fuel/air mixing capability under various flow conditions. The fuel ports were placed in various locations on the struts, including the leading edge, side, tip and wall. The performance of these strut-injection designs is determined based on the local equivalence ratio, total pressure recovery, and mixing efficiency in a rectangular flow path. Most of the strut designs have a backward-swept angle, except Strut J, which has a forward-swept angle. In general, the backward-swept strut transports the fuel upward toward the core flow. On the other hand, a forward-swept strut carries the fuel toward the bottom wall. The numerical result indicates that StrutE-les-1 has the best performance in terms of overall total pressure recovery and mixing efficiency. These computations will be followed by an experimental program to assess mixing, pressure loss, and general flowfield characteristics.