Optimization Design of Bionic PDC Bit Hydraulic Structure Based on Response Surface Method
Reasonable bit hydraulic structure can avoid mud bag phenomenon and improve drilling efficiency.In order to improve the hydraulic structure of bionic PDC bit,four different hydraulic structure schemes were numerically calculated based on K-e turbu-lence model and discrete phase model.The best scheme was the combination of nozzle and auxiliary nozzle.In order to determine the op-timal structural parameters under this scheme,a mathematical model with nozzle diameter x1,auxiliary nozzle diameter x2,radial dis-tance from nozzle to drill center x3,maximum velocity of sampling point D and average velocity of sampling point E as objective func-tions was established by response surface method.Based on regression analysis,the hydraulic structure of drill bit was optimized.The op-timal parameters were obtained as follows:nozzle diameter 16.36 mm,auxiliary nozzle diameter 8 mm,radial distance from nozzle to drill center 63.85 mm,and the hydraulic structure under this parameter was numerically calculated.The results show that the optimized hydraulic structure of the drill bit not only reduces the number of bottom hole velocity fluctuations,but also significantly improves the overall velocity,solves the original eddy current phenomenon,enhances the rock carrying performance of the drilling fluid and reducing the particle concentration.