气相爆轰在T形管中传播新现象的实验研究

对2H2/O2/Ar系统爆轰波在T形管(截面为40mm×40mm)中传播现象进行了实验研究.用烟迹片记录了T形管中爆轰波的胞格结构,用压电传感器记录了分叉口附近指定点压力时间曲线,得到了爆轰波在分叉口附近的平均速度和胞格图案演变.结果表明:初压P0≥2.67kPa,在水平和垂直支管下游区域(距离分叉口约3.5—6倍方管截面边长),分叉口影响消失,爆轰波恢复稳定,且强度基本保持不变.在分叉口绕射过程中,爆轰波在膨胀区中衰减,诱导激波阵面弯曲.两个支管中发生马赫反射,三波点迹线清晰可见.该传播特性是爆轰波的诱导激波和横波共同作用的结果.分叉口附近的胞格结构先消失再恢复,在无胞格和平衡胞格之间的区域存在细密胞格的过渡区,表征了在诱导激波与化学反应阵面分离后的区域中出现二次点火.P0=2.00kPa,水平支管中稳定自持爆轰能重建,垂直支管中爆轰熄灭.P0<2.00kPa,分叉口上游已不能形成稳定爆轰.还对胞格结构中的几个特征参数进行了测量,并初步分析了P0对这些参数的影响.

EXPERIMENTAL INVESTIGATION ON GASEOUS DETONATION PROPAGATION THROUGH A T-SHAPE BIFURCATED TUBE

The gaseous detonation of 2H$_{2}$/O$_{2}$/Ar mixture propagation through a T-shape bifurcated tube with a square cross-section 40\,mm$\times $40\,mm has been experimentally studied in this paper. The pressure histories at the specific ports were recorded by pizeo-electric transducers and cellular patterns around the T-shape were recorded by smoked foils respectively. The average velocity of detonation and the cell evolution were obtained. Experimental results indicate that the detonation wave is strongly weakened by the geometry around the T-shape tube. The interactions of leading shock and transverse waves contribute to the traveling characteristics of detonation. In the downstream region far away from 3.5 to 6 times the tube cross-section size, a secondary steady detonation wave is re-established accompanying the appearance of regular cellular structures with the same sizes as the previous one. The cellular patterns also demonstrate the phenomena of diffraction, regular and Mach reflections of gaseous detonation. In the pass-by tube, it is noted that the cellular structure disappears in the region just downstream the start of the T-shape due to the separation of leading shock and reaction zone. With the propagation and reflection of the leading shock in the pass-by tube, the re-initiation occurs in the separated region between the leading shock and reaction zone. The re-initiation can be demonstrated by the clustered cellular structures on the smoked-foils, and it is critical in re-establishing of gaseous detonation here. As the initial pressure decreases to 2.00\,kPa, the steady detonation can be re-established in downstream region, but detonation extinguishes in the bifurcated tube. Also, based on the smoked foil records, several characteristic lengths and angles were measured and the initial pressure influences on them were analyzed.