Abstract: High-pressure water jet becomes invalid in cutting hard coal seam， and abrasive jet cutting technology is difficult to achieve continuous addition of abrasives. In order to overcome these difficulties， a self-priming abrasive jet nozzle using the forward and backward nozzle structure was designed on the basis of the principle of ejector. This nozzle can achieve continuous inhalation of coal particles produced by slotting to form abrasive jet， with the slotted capacity improved. By simulating the two-phase liquid-solid interaction， it was found that coal particles in the nozzle experience three acceleration stages at intake， mixing chamber and nozzle， respectively. According to the volume of particles and the final velocity of the particles， the most optimal nozzle structure was obtained: the front nozzle diameter is 3mm， the back nozzle diameter is 5mm， and the length of the back nozzle is 15mm. The comparison of the experiments results showed that the slotting efficiency of the self-priming abrasive nozzle was improved significantly compared to that of the traditional cutting seam.

Key words: coal seam cutting, self-priming, abrasive jet, nozzle, two-phase flow