Impact of Outlet Restriction on RDC Performance and Stagnation Pressure Rise

摘要

This study explores the effect that different outlet boundary conditions have on the performance and operation of a generic RDC device. A number of uniform outlet designs with varying blockage ratio, as well as a guide vane section with varying numbers of vanes, are placed downstream of an RDC. In addition to average and fluctuating static pressure, the stagnation pressure is measured at various places along the combustor. The gathered data is used to track the operational mode of the device and the wave speed of the associated detonation wave, which can attain values of up to 83% of the CJ velocity. A typical progression from a clapping mode towards a single wave mode is observed for almost all configurations, except one in which increased outlet blockage and plenum coupling lead to a longitudinally pulsating motion. It is shown that a sonic condition at the outlet promotes the single wave detonation process. Stagnation pressure data is employed to compare the performance of all configurations across the range of operating conditions, with the vane setup being the most efficient. The rise of stagnation pressure is shown to be influenced primarily by thermal power, with only minor influence of the operating mode. The equivalent available pressure (EAP) formulation is used to assess the performance of the device. While net pressure gain could not be realized in the operational range of this study, several design effects and the positive impact of increasing heat release are verified and the results are in line with reference CFD data.