Correlation between the critical tube diameter and annular interval for detonation wave in high-concentration argon diluted mixtures
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摘要: 建立圆管及环形管道系统研究临近极限下爆轰波在管道内传播失效机理。选用C2H2+2.5O2+70%Ar气体，采用光纤探针测量爆轰波在管道内传播速度，用烟迹法记录管道内爆轰波胞格结构。结果表明：初始压力远大于爆轰极限压力时，爆轰波在管道内以稳定速度传播；随着初始压力的减小，爆轰波速度逐渐降低；当初始压力一定时，爆轰波速度随着管道尺寸的减小而逐渐减小；当初始压力达到临界压力时，爆轰波在进入到管道内后其速度会逐渐衰减直至爆轰波完全失效。对于不同几何尺寸的圆管与环管，通过引入无量纲参数d/λ及w /λ(d为圆管管径，w为环管间距，λ为爆轰胞格尺寸)得出，爆轰波在管道内传播的临界圆管直径为环形间距的2倍，与理论模型结果相吻合，验证了稳态气体基于爆轰波波面曲率的失效机理。Abstract: Detonation tube including driver section and test section was built to investigate the failure mechanism of detonation wave near the limits. The mixture of C2H2+2.5O2+70%Ar was investigated experimentally. Fiber optics was used to measure detonation velocity. Smocked foils were used to record the detonation cellular structure. The results show that, with the initial pressure far lager than the critical pressure, detonation wave propagates at a constant value in the tubes. Detonation velocity decreases with the decreasing initial pressure. With a given initial pressure, the detonation velocity decreased as the tube diameter (or channel interval) decreased. Under the critical pressure, the detonation velocity propagated a short distance in the tubes and then decreased gradually until complete failure. For different geometries tubes and channels, by introducing dimensionless parameter d /λ and w/λ (d the dameter of the round tube, w the interval of the annular channel and λ the size of detonation cellular), the results show that the critical thickness is half of the critical diameter. Good agreement is found between the experimental measurements in both geometries which supports this conclusion and theoretical mode. The failure mechanisms based on the detonation front curvature for stable detonation in mixtures that are highly argon diluted are well defined.
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图 5 爆轰胞格结构随初始压力的变化(d=50.8 mm)
Figure 5. Stuctures of the detonation cellulars vary with the initial pressure (d=50.8 mm)
表 1 圆管几何尺寸
Table 1. Round tube size
d/mm L/mm t/mm 1.5 2 438 0.8 3.2 2 438 1.6 12.7 4 118 3.2 31.7 4 118 3.2 50.8 3 048 3.2 
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表 3 圆管实验结果
Table 3. Experimental results of round tubes
d/mm pc/kPa λ dc/λ 50.8 1.1 306.47 0.166 31.7 1.5 202.51 0.157 12.7 3.2 73.60 0.173 3.2 9.8 16.50 0.194 1.5 20.0 6.36 0.236
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表 4 环管实验结果
Table 4. Experimental results of annular channels
w/mm pc/kPa λ wc/λ 5.9 3.5 65.30 0.0903 3.2 6.0 31.79 0.1006
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表 5 圆管ZND化学反应区长度
Table 5. ZND reaction zone length of round tubes
d/mm pc/kPa ΔZND/mm dc/ΔZND 50.8 1.1 1.818 27.94 31.7 1.5 1.273 24.94 12.7 3.2 0.553 22.96 3.2 9.8 0.148 21.54 1.5 20.0 0.065 23.08
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表 6 环管ZND化学反应区长度
Table 6. ZND reaction zone length of annular channels
w/mm pc/kPa ΔZND/mm wc/ΔZND 5.9 3.5 0.482 12.2 3.2 6.0 0.259 12.3
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