Study and Analysis of Fuel Injection at Busemann Inlet at Mach 7

Abstract

The incomplete mixing of fuel and the drag induced in the engine are the main problems encountered in scramjets.Proper mixing of fuel can be achieved if the fuel is injected from the inlet of the engine. The fluid domain of Busemann Inlet at Mach 7 with boundary layer fuel injection using slot injectors along the wall was simulated with hydrogen fuel. Static pressure ratio at throat and inlet, along with Mach number at the throat were the design parameters of the Busemann inlet. Hydrogen fuel injection at two different equivalence ratios (0.3 and 0.7) was simulated successively at a temperature of 100 K and Mach 2.5. The state of mixing was studied for three different injection angles (30°, 45°, and 60°) for different equivalence ratios. The injection angles do not have a substantial effect on the hydrogen fuel mixing with the mainstream flow for equivalence ratio 0.3 Whereas, the dispersion of fuel increases as the increase in injection angles for equivalence ratio 0.7. But the total pressure recovery is maintained to the design value for equivalence ratio 0.3 rather than 0.7. Similarly, 45° fuel injection maintains a higher total pressure recovery than in other injection angles of 30° and 60°. Injection technique other than slot injection can be used to study further the effect of fuel mixing in Busemann Inlet.