The Effect of Downhole Turbine Modeling Parameters on Mechanical Output Performance

Small-size turbine drilling tools have better application prospects in small borehole drilling and so on. Based on the SST model, the influence of a Φ73 mm turbine knuckle-shape parameters on the mechanical energy output characteristics was simulated, and the vortex structure of the turbine internal flow field was analyzed to find the law. First, the influence of leading-edge radius on the turbine internal flow field is concentrated on the rotor suction surface. Second, as with the axial clearance, there is a regular effect of the trailing-edge radius on the flow field in the rotor as a whole and in the middle and rear parts of the stator. Third, the change in the installation-staggering angle does not change the turbine output performance. The output performance is optimal when the leading-edge radius of the Φ73 mm turbine blade is 0.8 mm, the trailing-edge radius is 0.4 mm, and axial clearance is 6 mm. At the same time, the effects of rotational speed, displacement, and fluid viscosity on the output performance of the turbine were simulated, and the output performance of the turbine of this size was predicted under the conditions of low rotational speed, small displacement, and high fluid viscosity. Under the working conditions of conventional drilling parameters, the output pressure drop of a single-stage turbine can be up to 0.018 MPa or less, and the torque is more than 1.6 Nm. If 100–200-stage turbines are used as the power, the output torque can reach 150–300 Nm, which can meet the demand of rock-breaking in the mine.