Abstract
The aggressive ability of cavitating jets generated by a double-hole nozzle was investigated under an ambient pressure condition to improve the erosion efficiency for potential applications such as underground drilling. The erosion damage was experimentally investigated for a series of pitch-hole ratios to understand the erosion mechanism of the double-hole cavitating jets. The flow characteristics of various erosion patterns were numerically investigated using two-phase computational fluid dynamics (CFD) calculations. The stages of erosion suppression in the pitch-hole ratio range ω_p ∈ [1.25, 3] and erosion enhancement in ω_p ∈ [3.5, 6] were observed based on the mass loss △m across the entire range of standoff distance ratio l_s. Two erosion patterns were identified according to the erosion features, designated as A and B, with increasing standoff distance ratio l_s. Erosion occurs in multiple scattered regions in pattern A and which appears as two symmetric D-shaped regions in pattern B. In contrast to the single-hole jet, the aggressive ability was significantly improved a ω_p = 4.5 with higher △m peaks. Double-hole cavitating jets at the optimum pitch-hole ratio achieve the highest streamwise velocity and the weakest interaction between the two jets. The cavitation clouds in the impinging jets generated by the optimum pitch-hole nozzle primarily collapse in the D-shaped main erosion region, which enhances the erosion damage of the double-hole cavitating jets at the optimum standoff distance ratios.
NSTL