Flow field characteristic of water jet with air ring protective layer under submerged environment and the orthogonal optimization of nozzle structure

Abstract A water jet with an air ring protective layer is a promising rock‐breaking and cutting rate improvement method in submerged environment, such as oil–gas drilling. The flow field characteristic determines the impinge performance affected by nozzle structure parameters. In this study, under environment was numerically simulated. obtained analyzing distributions of velocity content at different cross sections. effects several critical parameters on isokinetic core length axial were investigated adopting orthogonal design method. results show that radial direction includes high‐speed zone, layer, air–water mixed having advantages concentrated energy axis region, long section length, low‐velocity attenuation. influence degrees X = 0.3 m are: length‐diameter ratio > outlet diameter conic angle water‐air spacing diameter, respectively. both increase exponentially increasing first rapidly then slowly decreases water–air spacing. There optimal 15° appropriate 3–5 mm. With length–diameter ratio, they decrease slow down, indicating conical more suitable for ring. And 0.9–1.2 mm proper diameter.