Effect of Diffusion Time on Deflagration and Detonation Parameters of Ethene-Air
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摘要: 为探究在有限空间中,初始压力为0.25 MPa、两处乙烯气体瞬时源在不同扩散时间下的燃爆特性,在内径200 mm、高5 400 mm的立式激波管中,采用上下进气方式,在强起爆条件下,测定5个不同扩散时间下3种浓度的乙烯-空气混合气体(C2H4-Air)的燃爆参数。实验结果表明,扩散时间大于1 h后,3种浓度的C2H4-Air混合气体燃爆参数趋于一致。4.00%(体积分数)C2H4-Air在当前实验条件下未能达到爆轰。6.67%C2H4-Air在5个扩散时间均可达到爆轰,扩散时间为1 h时的爆压、爆速分别为4.24 MPa、1 719 m/s。8.89%C2H4-Air在0.08 h扩散时间下只发生爆燃,扩散时间为0.5 h及以上发生爆轰,扩散时间为1 h时的爆压、爆速分别为4.31 MPa、1 813 m/s。通过烟熏技术捕捉到6.67%、8.89%的C2H4-Air混合气体的爆轰波胞格,胞格宽度分别为8.22、14.15 mm,长宽比分别为1.44、1.57。Abstract: A vertical shock tube of 200 mm in inner diameter and 5 400 mm in height was used to study the deflagration and detonation parameters of ethane-air mixtures under a high initial pressure(0.25 MPa).The gas mixtures flow into the shock tube through two inlets at two ends of the shock tube instantaneously, the experiments of 3 concentrations of mixtures and 5 diffusion times were carried out with high initiation energy.The experimental results show:when the diffusion time exceeds 1 h, the trends of the deflagration-detonation parameters of C2H4-Air for 3 concentration are similar; 4.00%(volume fraction)C2H4-Air can't meet the detonation criteria under the experiment condition; 6.67%C2H4-Air can be ignited at 5 diffusion times, the detonation pressure and velocity separately are 4.24 MPa and 1 719 m/s when the diffusion time is 1 h; 8.89% C2H4-Air deflagrates when the diffusion time is 0.08 h, the detonation pressure and velocity separately are 4.31 MPa and 1 813 m/s when the diffusion time is 1 h; We seized the detonation cell size of 6.67%, 8.89%C2H4-Air by smoked foil, the width separately are 8.22 and 14.15 mm, L/λ separately are 1.44 and 1.57.
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Key words:
- gas explosion /
- diffusion time /
- detonation parameters /
- vertical shock tube /
- direct ignition /
- cell size
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表 1 传感器位置和量程
Table 1. Position and range of pressure sensor
No. Height/(m) Measurement range/(MPa) 2# 1.4 10 3# 1.9 10 4# 2.4 10 5# 2.9 10 6# 3.4 10 7# 3.9 10 表 2 起爆药量与能量输出
Table 2. Mass and output energy of ignited materials
Initiation source Output energy/(kJ) Initiation energy per area/(MJ/m2) 1D 5.94 0.19 1D+3g C4 23.53 0.75 1D+5g C4 35.25 1.12 表 3 C2H4-Air混合气体爆轰胞格尺寸数据
Table 3. Detonation cell size of C2H4-Air
C2H4
contentLength L/(mm) Width λ/(mm) L/λ Mean value Standard deviation Mean value Standard deviation Mean value Standard deviation 6.67% 11.70 2.28 8.22 1.93 1.44 0.10 8.89% 22.13 5.14 14.15 3.30 1.57 0.10 -
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