环缝宽度对两相旋转爆轰波压力与频率特性影响实验研究

Experimental Study on Effects of Annular Gap Width on Pressure and Frequency Characteristics of Two-Phase Rotating Detonation Wave

关键词:  环缝宽度  两相旋转爆轰波  当量比  压力特性  频率特性

Key words:  Annular gap width  Two-phase rotating detonation wave  Equivalence ratio  Pressure characteristics  Frequency characteristics

摘要:

为了研究空气喷注环缝宽度对两相旋转爆轰波压力与频率特性的影响，通过改变环缝宽度与当量比开展了大量实验研究。旋转爆轰发动机环形燃烧室外径、内径以及长度分别为204mm，166mm和155mm。汽油和高温空气采用高压雾化喷嘴与环缝对撞喷注的方式进行混合，以此提高推进剂的掺混效果与活性，发动机采用预爆轰管作为点火装置。实验通过燃烧室内测得的高频动态压力信号，对两相旋转爆轰波的传播稳定性、压力特性以及频率特性进行了详细分析。实验结果表明：在不同环缝宽度下均实现了高总温空气与汽油的两相旋转爆轰。当环缝宽度为3mm和4mm时，旋转爆轰波平均峰值压力与传播频率均随着当量比增大而增大；增加环缝宽度至6mm，爆轰波传播稳定性变差，平均峰值压力与传播频率随当量比先增大后减小。当环缝宽度为4mm时，获得的旋转爆轰波平均峰值压力最高，压力脉动强度最小，爆轰波传播稳定性最强。在一定工况范围内，增加当量比可有效降低爆轰波峰值压力脉动强度。此外，随着空气环缝宽度的增加，爆轰波传播频率整体降低。当环缝宽度为3mm，当量比为1.19时，爆轰波以单波模态在环形燃烧室内连续旋转传播，平均传播速度约为1176.6m/s，爆轰波传播速度存在严重亏损。

Abstract:

In order to study the effects of air injection annular gap width on pressure and frequency characteristics of two-phase rotating detonation wave， experiments were carried out by varying gap width and equivalence ratio. The outer diameter， inner diameter and length of rotating detonation engine annular combustor are 204mm， 166mm and 155mm， respectively. Gasoline and high temperature air are injected into the combustor through a nozzle-gap impinging model constructed of high pressure atomizing nozzles and annular gap to improve the mixing effect and chemical activity of propellant. A pre-detonator tube is used as ignition device. Based on high frequency dynamic pressure signals measured in combustor， the propagation stability， pressure characteristics and frequency characteristics of two-phase rotating detonation wave were analyzed in detail. Experimental results show that two-phase rotating detonation of high temperature and gasoline is realized with different gap widths. When the gap widths are 3mm and 4mm， average peak pressure and propagation frequency of rotating detonation wave increase with the increase of equivalence ratio. Increasing the gap width to 6mm， propagation stability of detonation wave become worse， and the average peak pressure and propagation frequency increase first and then decrease with the increase of equivalence ratio. The highest average peak pressure， the lowest pressure fluctuation intensity and the best propagation stability of detonation wave is obtained with the annular gap width of 4mm. Under a certain range of operating conditions， increasing equivalence ratio can effectively reduce the peak pressure fluctuation intensity of detonation wave. In addition， with the increase of air gap width， propagation frequency of detonation wave decreases in the entirety. At the gap width of 3mm and equivalence ratio of 1.19， single detonation wave propagates continuously in the annular combustor. The average propagation speed is around 1176.6m/s， and there is a heavy velocity deficit existing during the propagation of detonation wave.