Analysis of combustion mode and operating route for hydrogen fueled scramjet engine

•Combustion mode transition is the way to realize wide range operation of scramjet.•Combustion mode optimization can improve hydrogen fueled scramjet performance.•The optimal operation route of hydrogen fueled scramjet is given.

Hydrogen fueled scramjet is a candidate for use as the engine of the aerospace plane for its high specific impulse. To further improve the specific impulse performance, analysis of combustion mode and operating route for a hydrogen fueled scramjet engine was investigated in this study. A scramjet engine with two-staged hydrogen injection was simulated by one-dimension numeric method within the acceleration from Mach 4 to 7. Three typical combustion modes (scramjet-mode, transitional mode and ramjet-mode) could be attained by changing the total amount of fuel added or adjusting the fuel distribution between two injectors. Simulation results show that better thrust performance can be achieved as more fuel injected at the upstream fuel injector as possible, while ensuring the engine safety. From a standpoint of specific impulse maximization, an optimal scramjet combustion mode database was presented and the boundary of the combustion mode transition was determined. Meanwhile, optimal operating route was also suggested for scramjet operation in this study.