螺旋爆轰内部胞格结构实验探索

Experimental Research on Spinning Detonation Structure

关键词:  螺旋爆轰  胞格结构  环形管道  数字化分析  边界层效应

Key words:  Spinning detonation  Cellular structure  Annular channel  Digitalization analysis  Boundary layer effect

摘要:

为研究螺旋爆轰胞格结构，选取预混气C₂H₂+2.5O₂+85%Ar，C₂H₂+2.5O₂+70%Ar与C₂H₂+5N₂O在光滑管中进行爆轰实验，使用烟膜记录管道侧壁与端面胞格结构。编写MATLAB程序处理烟膜记录，比较侧壁横波间距、端面胞格直径平均值，以及相邻端面胞格中心点距离平均值与标准差。其中，侧壁横波间距明显大于管壁附近端面胞格直径平均值。另外，相较于稳定气，不稳定气近管壁与近管轴区域的端面胞格直径差异更大，不同压力下预混气C₂H₂+5N₂O近管壁与近管轴区域的端面胞格直径差异分别为47.91%，59.64%，40.42% 与37.21%。为进一步探索爆轰波内部结构，使用CH₄+2O₂在5，15与25mm宽度的环形管进行实验，对比侧壁及端面烟膜结果，可观测到内部螺旋横波旋转方式。相对环管宽度而言，初始压力是胞格尺寸的主要影响参数，而整体上外侧壁胞格尺寸稍大于内侧壁胞格尺寸。

Abstract:

In order to research the cellular structure of spinning detonation， pre-mixed mixtures C₂H₂+2.5O₂+85%Ar， C₂H₂+2.5O₂+70%Ar and C₂H₂+5N₂O were used in the detonation experiments in smooth tube. Inner-wall and end-on cellular structure were recorded by smoked foils. A MATLAB program was written to analyze the smoked foil results. The transverse waves spacing， end-on cell diameter average， and average and variance of adjacent end-on cell center distance were compared. The transverse spacing wave is more than the end-on cells average diameter which is near the tube wall. Compared with stable mixture， the end-on cells average diameter of unstable mixture shows larger difference among the end-on cells located at near tube wall and near tube axis. For unstable mixture C₂H₂+5N₂O under different initial pressure， the difference of average diameter of end-on cells located at near tube wall and near tube axis are 47.91%， 59.64%， 40.42% and 37.21%， respectively. Then， pre-mixed mixtures CH₄+2O₂ was used in annular channels which are 5， 15 and 25mm width to study further the cellular structure inside of spinning detonation. The transverse wave rotation can be recorded by smoked foils on the end and inside of the channel. Compared with the channel width， initial pressure is dominant parameter for cell size. Generally， cell size on the outer-wall of the channel is larger than that on the inner-wall.