Experimental study on the effect of equivalent ratio on working characteristics of gasoline fuel two-phase rotating detonation engine
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摘要: 为了研究当量比对汽油燃料两相旋转爆轰发动机工作特性的影响,开展了以高总温空气为氧化剂的气液两相旋转爆轰实验研究。旋转爆轰发动机环形燃烧室外径、内径和长度分别为202、166和155 mm。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混合,以此提高推进剂的掺混效果与活性,采用预爆轰管作为点火装置。实验通过改变汽油质量流量改变推进剂当量比,并基于燃烧室内测得的高频动态压力和平均静压,对气液两相旋转爆轰波的传播模态和传播特性以及发动机的工作特性进行了详细分析。实验结果表明:在当量比为0.79~1.25时,燃烧室内均实现了旋转爆轰波的连续自持传播,且随着当量比的增加,爆轰波传播模态从双波对撞/单波的混合模态转变为单波模态;降低当量比至0.61~0.66,爆轰波传播稳定性变差,传播模态表现为间断爆轰以及零星爆轰;进一步降低当量比至0.53,爆轰波起爆失败。此外,燃烧室平均绝对压力与爆轰波平均传播频率均随着当量比的增加呈先增大后减小的趋势,极大值出现在当量比1.19附近。在此工况下获得了最佳实验结果,旋转爆轰波的平均传播频率为1 900.9 Hz,平均传播速度为1 110.8 m/s,与高频压力信号经快速傅里叶变换得到的主频基本一致,爆轰波传播速度存在严重亏损。Abstract: To understand the effect of equivalent ratio on the working characteristics of gasoline fuel two-phase rotating detonation engine, a gas-liquid two-phase rotating detonation experimental study with high total temperature air as oxidant has been carried out in this work. The outer diameter, inner diameter and length of rotating detonation engine annular combustor are 202, 166 and 155 mm, 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 reactivity of propellant. A pre-detonator tube is used as ignition device. In experiments, the equivalent ratio of propellant is controlled by changing the gasoline mass flow rate with constant air mass flow rate. Based on high frequency dynamic pressure signals and average static pressure measured in the combustor, the propagation mode and propagation characteristics of the gas-liquid two-phase rotating detonation wave and working characteristics of the engine were analyzed in details. Experimental results show that continuous self-sustained propagation of rotating detonation wave is realized in the combustor during the equivalent ratio ranging from 0.79 to 1.25. With the increase of the equivalent ratio, the propagation mode of detonation wave transforms from double wave collision/single wave mixed mode to single wave mode. By reducing the equivalent ratio to 0.61−0.66, the propagation stability of detonation wave becomes worse, and the propagation mode transforms to the intermittent detonation or sporadic detonation. When reducing the equivalent ratio to 0.53, the detonation initiation fails. In addition, with the increase of the equivalent ratio, both the average absolute pressure in the combustor and the average propagation frequency of detonation wave increase and then decrease, and the maximum value appears around the equivalent ratio of 1.19. Under this condition, the best experimental results are obtained. The average propagation frequency of detonation wave is 1 900.9 Hz, and corresponding average propagation velocity is 1 110.8 m/s, which are consistent with the main frequency obtained from Fast Fourier Transform of high frequency pressure signal. There is a heavy velocity deficit existing during the propagation of detonation wave.
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表 1 实验工况
Table 1. Experimental conditions
工况 当量比 空气总温/K 空气流量/(g·s−1) 汽油流量/(g·s−1) 传播频率/Hz 传播模态 1 0.53 713.0 1 110.0 38.4 — 起爆失败 2 0.61 713.0 1 110.0 44.2 1 452.0 零星爆轰 3 0.66 713.0 1 110.0 47.9 1 521.7 间断爆轰 4 0.79 713.0 1 110.0 57.3 1 613.7 混合模态 5 0.84 713.0 1 110.0 62.4 1 818.2 混合模态 6 0.97 713.0 1 110.0 70.3 1 827.3 混合模态 7 1.06 713.0 1 110.0 76.3 1 849.1 单波 8 1.19 713.0 1 110.0 85.7 1 900.9 单波 9 1.25 713.0 1 110.0 90.6 1 878.4 单波 -
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