Study on noise induced by cavitation flow in orifice plates

Abstract

In water supply pipelines, the installation of multiple orifice plates as throttling components can lead to significant noise generation, caused by the cavitation flow downstream, which in turn, can negatively impact the stealth performance of ships and human health. This study aims to investigate the noise reduction characteristics of orifice plates used for throttling. For this purpose, a test rig was established to measure the noise generated by cavitation flow through orifice plates with varying porosity rates, along with the corresponding pressure losses. Additionally, Large Eddy Simulation (LES) and the Zwart-Gerber-Belamri (ZGB) cavitation model were used to numerically simulate the cavitation flow through orifice plates with a porosity rate of β = 0.4. The results show that the pressure loss coefficient is approximately inversely proportional to the porosity rate and follows a power function with the Reynolds number, with the exponent closely related to the porosity rate. During the cavitation stage, the sound pressure level significantly increases in the high-frequency range of 500–8000 Hz, exhibiting broad-spectrum characteristics. During the initial cavitation, bubbles are mainly confined to the surface of the orifice wall. Nevertheless, under conditions of intense cavitation, the generation of bubbles in the shear layer and trail-flowing region is induced by vortex cavitation. Moreover, cavities form at the intersection of the jet and shear layer, which extend towards the orifice plate. To optimize the noise reduction performance of orifice plate throttling components, it is advisable to maintain the porosity rate within the range of 0.40–0.49.