Suppression of pressure feedback of the rotating detonation combustor by a Tesla inlet configuration

Abstract

With the increase in the inlet throat area, the rotating detonation combustor (RDC) can obtain higher pressure gain. However, the pressure feedback caused by the rotating detonation wave (RDW) can affect the upstream components of combustion chamber and interfere with the stable operation of RDC. Therefore, to obtain outstanding performance, it is imperative to investigate the suppression of pressure feedback. In this study, kerosene and 28.5% oxygen-enriched air (at room temperature) were taken as the propellant, and the tesla valve inlet configuration was applied to RDC, and the effect was compared with that of the traditional inlet configuration to suppress pressure feedback. A series of experiments were conducted to examine the operation characteristics of Tesla RDC and the effect and mechanism of suppressing pressure feedback. Under similar conditions, Tesla RDC can effectively transform the longitudinal pulsed detonation (LPD) mode into the rotating detonation (RD) mode, thus expanding the operating range of RDC. RDC under the exit nozzle with a small area ratio (0.25) was successfully realized. The operating range of Tesla RDC can be expanded by 300% and 94.7% at an exit area ratio of 0.5 and 0.65, respectively. The bypass channel in Tesla valve inlet configuration is the key to expanding the operating range. Directing pressure feedback to the bypass channel can effectively weaken the influence on the main inlet channel and shorten the inlet recovery time. Two quantitative evaluation indexes of pressure feedback were established; one is the percentage of the pressure fluctuating amplitude in the air plenum to the pressure amplitude of the detonation wave (PFdw), and the other is the static pressure of the air plenum, PFap. By analyzing the dynamic pressure signal upstream of the combustor, it was found that pressure disturbance is in the form of a pressure wave during the upstream return of the combustor, and the return speed is close to the local sound speed. Pressure feedback is mainly suppressed at the inlet throat, and PFdw is reduced by approximately 14% due to drainage of the bypass channel. Tesla RDC exhibits a good suppression effect on LPD mode, PFdw is significantly lower in the large exit nozzle area ratio, and the minimum value is 23%. PFap has an approximately linear relationship with the equivalence ratio, and the minimum value is 7.7%. Overall, this study demonstrates that Tesla RDC has excellent potential in widening the operation range and suppressing the pressure feedback, providing an innovative method for improving the performance of RDC.