Erosion Behavior and Structural Optimization of a Drill-Bit-Integrated Vibration Detection Tool Based on CFD–DPM

Drill-bit-integrated vibration sensors face localized erosion from sand-laden drilling fluid. We applied a computational fluid dynamics–discrete phase model (CFD–DPM) incorporating the realizable k–ε turbulence, Forder rebound, and Oka erosion models to analyze erosion and optimize tool geometry. Erosion was concentrated at channel transitions and guide-bracket roots. Among the investigated conditions, inlet velocity produced the largest variation in predicted erosion, and 200 μm particles generated the highest erosion among four tested sizes. An optimized design with a 45° semi-conical guide hood, two guide brackets, and a 4 mm root fillet reduced the predicted maximum erosion flux from 7.62 × 10−4 to 2.21 × 10−4 kg·m−2·s−1, or approximately 71%. Sampling variability was assessed through five DPM repeats per condition; fine-grid convergence indices were 1.88% and 2.94% for the baseline and optimized geometries, respectively. Prototype tests confirmed signal acquisition and rotation tracking. Sand-laden erosion tests at 15 m·s−1, 100 μm, and 0.01 kg·s−1, using three specimens per geometry and 1800 s exposure, showed 56.72% lower overall mass-loss rate and 69.54% lower registered local-window depth rate. These short-duration measurements support erosion mitigation, but do not directly validate the predicted peak-flux reduction.