复合材料边界厚度对单空泡溃灭的影响及机理

The many advantages of composite materials are crucial for the development of high-performance hydraulic machinery. In the paper, the schlieren image of the collapse process of a single cavitation near the composite boundaries of three thicknesses is observed and analyzed by combining high-speed schlieren observation technology and image processing technology. The evolution process of the shock wave of single cavitation collapse and the surrounding flow field structure is also discussed. Furthermore, the paper utilizes a hydrophone pressure signal measurement system to monitor the pressure fluctuation process in the bubble flow field and extracts spectral characteristics. The study shows that the thickness of the composite material boundary significantly affects the evolution process of the bubble collapse, the pressure of the shock wave, and its frequency-time characteristics. When γ = 1.0, the study found that there are significant differences in the bubble collapse process and pressure at the boundaries of the three types of composite materials. The main stages include expansion, contraction, and rebound when the bubble collapses. During bubble expanding, the cross-sectional diameter ratio d* of the bubbles varies differently as a function of the dimensionless distance γ from the different thickness boundaries. During the contraction phase, the bubble divided-collapses at the δ = 0.5 mm boundary and generates high-speed jets at the δ = 1.0 mm and 2.0 mm boundaries. During the rebound phase, the bubble collapses to produce a double-ring shockwave near the δ = 0.5 mm boundary, while only a single-ring shockwave occurs near the δ = 1.0 mm and 2.0 mm boundaries. At the δ = 0.5 mm boundary, three pressure peaks can be detected during collapse, whereas only two pressure peaks are observed at the δ = 1.0 mm and 2.0 mm boundaries. As γ increases, the intensity of the frequency components in the pressure signal gradually increases, and the influence on the bubble collapse decreases with decreasing boundary thickness.