EFFECT OF FIN-GUIDED FUEL INJECTION ON SCRAMJET PERFORMANCE

摘要

Supersonic mixing and combustion characteristics were compared between two fuel injector configurations, one involving a fin-guided approach, and the other, a normal injection approach to be used as the baseline. Both non-reacting and reacting scramjet experiments were conducted at an isolator entry Mach number of 2.1. In non-reacting flow experiments, the fin-guided configuration performed substantially better in terms of both mixing enhancement and stagnation pressure savings, yielding a multifold increase in the fuel penetration height and an 85% reduction in shock-induced pressure loss. In reacting flow experiments, however, the results were mixed as a separate cavity was added to assist with flameholding. The cavity improved the flame stability and ignition characteristics, most effectively for the baseline configuration. For fin-guided configuration, the cavity was less effective as more fuel was directed to the supersonic core, leaving less fuel for the cavity. Ultimately, the reacting flow remained supersonic throughout the fin-guided configuration, whereas it appeared to transition to subsonic flow in the baseline configuration near the cavity. Observation from fin-guided configuration can be explained with distributed heat addition into supersonic flow, similar to weak detonation type local reaction. On the other hand, local reaction in the baseline configuration downstream of the cavity resembled weak deflagration waves.