Aerodynamic performance enhancement of a variable-geometry dual-mode combustor designed by the method of characteristics

Wide-range scramjet is a part of the key power systems in future reusable hypersonic aircrafts, only the wide-range combustors with great performance can make the scramjet operate in a wide speed range. Through the method of characteristics, this paper designed a wave-elimination variable geometry combustor with a 20° deflection angle. The numerical simulation of the cold flow shows that the aerodynamic performance of the smooth wave-elimination combustor is greatly improved compared to the deflected combustor, and this improvement is more obvious at high operating Mach number. Also, the total pressure recovery coefficient of the wave-elimination combustor is above 0.8 when the combustor operates in different expansion ratios and freestream Mach numbers. The experimental study found that, under the expansion ratio of 1.8, the 20° wave-elimination combustor has a higher internal pressure compared with the 12° deflected combustor. In addition, the total pressure recovery coefficient is increased by 14.8% and 12.6% at the equivalent ratio of 0.6 and 1.0. This verified the advantage of the wave-elimination design, and proved that the wave-elimination design of the combustor is of great significance in improving the performance of the variable-geometry combustor.