Interaction of a gaseous fuel jet with shock-wave-rich airflow

The mixing of a gaseous fuel jet injected into a shock-wave-rich supersonic airflow has been examined. Different airflow Mach numbers and injection configurations (parallel, oblique, and normal) have been investigated numerically using a validated code. It was found that the shock-wave-rich environment, i.e. the shock train of the airflow, aids to a great extent in mixing enhancement for all injection configurations, especially at small oblique injection angles close to the parallel configuration. Unlike what was shown in previous research on fuel injection in shock-free supersonic airflows that normal or oblique injection at angles as large as 30° or 60° is inevitable to achieve sufficient mixing, substantial mixing improvement is provided by shock-wave-rich airflows. Fuel injection at small oblique angles of only about 5° improves mixing while minimizing the pressure losses accompanying the fuel injection, which leads to increased thrust. Due to the lack of experimental data for validation, the code was validated by using it to numerically simulate part of the results of a past experimental investigation from the literature. Good agreement of the simulation results and the actual flow field data was observed. The global features of the flow under high-speed conditions are similar to those reported previously, so that our results of mixing in shock-rich supersonic flows provide good insights on a more favorable fuel injection configuration that provides better mixing with lower losses and higher thrust.