无阀式脉冲爆震火箭发动机运行稳定性实验

Despite the ability of the valveless scheme to produce high frequency detonations, the problems leading to unsteady operations such as deflagration, ignition failure, and discrepancy in frequencies of operation and ignition are not clear. To study the influence of supply conditions on steady operations of the pulse detonation rocket engine, experiments have been conducted based on the valveless mode. Ethylene and oxygen-enriched air have been utilized as fuel and oxidizer, respectively. Influence of the oxygen volume fraction on the operation stability has also been analyzed. The results indicate that steady detonations are available only when the equivalence ratio is within a proper range, i.e., 1.2-1.7 and 0.8-2.3, when the oxygen volume fractions of 40% and 66% are used, respectively. The range of the equivalence ratio increases for producing detonation when the oxidizer with the volume fraction of 66% is used. In addition, pressure oscillations near the closed end of the detonation tube will propagate upwards to the supply passages when fully-developed detonations are produced, and thus flow oscillations, with a frequency times of the detonation frequency, will be induced inside the supply passages. However, the flow oscillations appear disorderly if steady detonations are not obtained in the detonation tube. Since the disorderly flow oscillations inside the supply passages will further influence the operation stability, measures to control them should be considered.