气射流破煤是高压气体经喷嘴加速，在空气中自由发展，最终冲击破煤的连续综合过程。基于空气动力学与岩石力学理论，分析了气射流破煤的连续过程机理，推导了连续过程数学模型并建立了破煤能力与破碎坑特征的判识准则。分析认为，高压气体经缩放型喷嘴实现超声速跃迁加速流动;自喷嘴喷出的气流在空气介质的剪切作用下，轴向速度衰减，径向断面扩张;当射流冲击作用于煤体后，产生破碎核和延展裂纹，在拉伸作用下发生失效破坏，形成塑性破碎坑。选取3种不同强度的煤体和1种砂岩进行的气射流破煤规律计算结果表明，当提高喷嘴入口压力和喷嘴直径时，气射流滞止点处压力均不断增大，在低压力入口条件下，气射流可对强度较小的煤体造成冲蚀破坏，当入口压力达到16 MPa时，可实现对砂岩的冲蚀破坏;随着射流压力的提高，冲蚀形成的破碎坑轴向深度和径向长度都不断增大，但轴向深度增加量要远大于径向长度增加量，破碎坑形状由最初的锥形渐变为橄榄球形。

Aiming at the defects of water seal inhibiting gas desorption and reducing coal permeability during the application of hydraulic anti-reflection measures in soft and low-permeability coal seams,a technical method for perforating coal with high-pressure gas jets to break coal and increase permeability is proposed,at the same time in order to understand the characteristics of air jet punching coal. Based on the aerodynamic theory and rock mechanics,the mechanism of the full continuous process of gas jet breaking coal is analyzed,the corresponding mathematical model is proposed and the criteria for determining coal breaking capacity and erosion pit characteristics are established. It is concluded that the high pressure gas accelerates through the Laval nozzle,the axial velocity decreases and the radial section expands under the shear action of the air medium. When the gas jet impact applies on the coal body,the broken core and the extended crack are formed,and the failure occurs under tensile action,which induces the plastic fracture pit. Calculations of the capability of gas jet breaking coal are conducted for 3 different strength coals and 1 sandstone cases. Results show that the pressure at the stagnation point of gas jet increases with the increasing inlet pressure and nozzle diameter. Under the condition of low inlet pressure,the gas jet can cause erosion damage to the coal with lower strength,and when the inlet pressure reaches 16 MPa,the erosion and failure of sandstone is achieved. With the increase of jet pressure,the axial depth and radial length of the broken pit are increased,while the increment of axial depth is much larger than the increment of radial length. The shape of the broken pit is conical initially but changes to rugby shape gradually.