Study on the Influence of Inlet Inclination Angle on the Erosion Characteristics of a Drilling Float Valve

Localized erosion near the valve cover and pin shaft can impair the reliability of drilling float valve. This study investigates an eccentric contraction modification for a 62 mm float valve, in which the small-end cross-section is shifted away from the pin shaft while the diameters of both end sections remain unchanged. Computational fluid dynamics simulations incorporating the RNG k–ε turbulence model, discrete phase model, and Oka erosion model were conducted to investigate the erosion characteristics for inlet inclination angles of 4.5–8.5°. At a flow rate of 20 L/s, a solid volume fraction of 0.5%, and a drilling-fluid viscosity of 20 mPa·s, increasing the inclination angle from 4.5° to 8.5° reduced the average erosion rates of the valve cover and valve spool body by 94% and 51%, respectively. The modification redirected particle-laden flow away from these critical components and reduced concentrated particle impacts. The effects of particle size, fluid viscosity, and solid concentration were also examined. Comparative tests conducted for 15 h at 20 L/s and a sand volume fraction of 15% showed visibly less valve-cover damage for the structural optimization of float valve, providing qualitative support for the predicted improvement. An inclination angle of 8.5° is recommended within the investigated geometric and seal-installation constraints.