气体流动阻力损失对反向扩孔气动冲击器性能的影响

为了研究反向扩孔气动冲击器内部气体流动阻力损失对其性能的影响，在简化复杂的气路基础上，从其结构和工作原理出发，分析了冲击器工作过程中气体流动所产生的压力损失；在有压力损失的条件下，研究冲击器气腔内气体变化特性，建立了冲击器的工作过程数学模型；根据数学模型，应用MATLAB程序进行计算机仿真运算，得到了冲击器工作过程中压力损失曲线，以及压力损失条件下活塞运动特性和各腔压力变化规律.研究结果表明:气体流动阻力损失影响冲击器破岩效率，使得冲击器活塞运动末速度从5.05 m/s下降到4.22 m/s，冲击频率从5.00 Hz下降到4.28 Hz；冲击器尾气压力仅为0.140 MPa，低于设计值0.185 MPa，影响冲击器尾气排屑. 

Influence of Gas Flow Resistance Loss upon Performance of Back-Reaming Pneumatic Impactor

In order to study the influence of flow resistance loss of gas upon the performance of a back-reaming pneumatic impactor, the complex gas path in the working impactor was simplified based on its structure and working principle, and the flow resistance loss of gas during the process was analyzed. Then, the changing characteristics of gas in the cavity of impactor were studied in presence of pressure loss, and a mathematical model for impactor's back-reaming operation was established. Based on the model, numerical simulations were conducted with a MATLAB program; and the pressure loss curve, the movement characteristics of piston and the law of pressure change in each cavity during the working process were obtained in presence of pressure loss. Results show that the flow resistance loss of gas will decrease the end speed of piston from 5.05 to 4.22 m/s and the impact frequency from 5.00 to 4.28 Hz, thus affecting the rock-breaking efficiency of impactor. In addition, the exhaust pressure of the impactor is only 0.140 MPa, which is lower than the designed value (0.185 MPa), leading to a poor performance of chip removal.