Performance enhancement of rotating detonation afterburner through combined injection scheme

Abstract

This study proposes a combined injection scheme to address the suboptimal fuel-oxidizer mixing efficiency in wide-throat configurations of rotating detonation afterburner (RDAB). Through comparative analysis of detonation wave propagation characteristics, combustor performance metrics, and matching stability parameters between wall injection and combined injection schemes, we demonstrate the operational advantages of implementing the combined injection strategy in RDAB system. The propagation characteristics of the detonation wave, the performance of the combustor, and the stability parameters of the component's coordinated operation were compared under the wall injection and the combined injection schemes. Key findings demonstrate that the combined injection approach successfully extends the fuel-lean limit of RDAB. However, this extension effect diminishes with decreasing nozzle exit area ratio. At A₈/A_3.1 = 1.545, the fuel-lean limit improves from 0.84 to 0.73. Under higher nozzle exit area ratios, combined injection enhances detonation wave velocity, propagation stability, and wave strength. When the nozzle exit area ratio is relatively high, the use of a combined injection scheme can increase the detonation wave propagation speed, propagation stability, and detonation wave intensity, among which the increase in detonation wave intensity is the most significant, with the maximum increase in detonation wave intensity reaching 180 %. Regarding performance parameters, while the intensified detonation wave improve pressure gain capability, they simultaneously amplify upstream pulsating pressure feedback intensity. Due to the absence of an effective pulsating pressure feedback suppression structure, the intake loss of the combustor increases, resulting in a slightly lower total pressure recovery coefficient for the combined injection scheme compared to the wall injection scheme. In terms of system matching stability, enhanced detonation wave intensity elevates combustor intake blockage ratio, leading to higher upstream plenum pressure levels. Overall, this study demonstrates the significant potential of combined injection strategies in enhancing detonation wave intensity and fully exploiting the pressurization capability of detonation combustion. The work provides an innovative approach for structural design of RDAB, while clarifying future development directions. These findings hold crucial implications for advancing key technologies in turbine-based continuous detonation engine.