关键词: 自振射流, 装置结构, 频率特性, 低频脉动, 高频振荡

Abstract: The frequency characteristics of self-resonating water jet include low-frequency pulsation and high-frequency oscillation, the occurrence mechanism and application conditions of which are quite different, while it is less reported. The device producing the jet is regarded as a whole, based on the fluid network theory, the mathematical model of the device is established to obtain the acoustic natural frequencies of the fluid network and the nozzle. Based on the signal analysis method, the whole frequency spectrum of the self-resonating jet is obtained, then the relationship between the device configuration and the frequency characteristics of the jet is discussed. The experimental results show that a complete spectrum of the self-resonating water jet consists of two parts, namely the low frequency pulsation frequencies and the high frequency oscillation frequencies, but the difference between these two frequency ranges is nearly two orders of magnitude. The low frequency pulsation of the self-resonating water jet is usually caused by the fluid disturbance inside the pipe network, when the disturbance frequency is close to the acoustic natural frequency of the pipe network, the low-frequency oscillation is enhanced. While the high-frequency oscillation is caused by the vortex-induced vibration at the nozzle exit. When the vortex shedding frequency is close to the acoustic natural frequency of the nozzle, the acoustic resonance occurs and the high frequency oscillation is generated. The low frequency pulsating jet is not affected by the shape of the nozzle outlet and external environmental parameters, so it can be applied to non-submerged or low confining pressure environments, while the high frequency oscillating jet is strongly affected by the above factors, so it can be applied under confining pressure conditions. The research results reveal the relationship between the device configuration of the self-resonating water jet and the frequency characteristics of the jet, which provides a theoretical basis for the structural design of the jet device and the application of the water jet in deep-sea area.

Key words: self-resonating water jet, device configuration, frequency property, low-frequency pulsation, high-frequency oscillation