Analysis of Flow Noise and Vibration Performance for Heat Supply Network Bleed Valve

Abstract

The heat supply network bleed valve is located in the steam pipe of the steam turbine heater. When conveying the steam medium of high temperature and high pressure, it impacts the valve disc and pipe wall, resulting in flow-induced vibration and noise of the pipe, resulting in excessive pipeline vibration, which is not conducive to the normal operation of the heat supply network and stable steam supply. In this paper, by using large eddy simulation turbulence theory to study bleed valve disc under different rotation angle operating characteristics, pipe flow field regularity of distribution, and the pressure pulsation of measuring points, the Q criterion is applied to analyze the locomotion mechanism of vortex structure in the downstream flow field of the valve disc, the use of common noise prediction method to calculate the noise of the heat supply network structure features, analysis of the inherent law of flow-induced vibration. It is found that with the increase of the rotation angle of the valve disc, there is an obvious negative pressure center area at the back of the valve disc, and the vortex is formed under the action of the adverse pressure gradient. The decrease in vortex size makes the flow efficiency at the back of the valve increase significantly. Large eddy simulation results show that the fluid generates a double vortex structure similar to the dean vortex behind the valve, and is eventually broken and separated due to the dissipation of viscous turbulent kinetic energy. The smaller the rotation angle is, the more seriously the dissipation vortex blocks the flow area near the pipe wall. The noise characteristics of the flow field in the heat supply network present a dipole state and the overall broadband characteristics. The energy of the flow field is concentrated in the low and middle frequency, and there is a peak of noise SPL. Simulation results showed that when the valve disc rotation angle is less than 30°, the vortex structure will seriously block the pipeline flow area, accounting for more than 90%, and the pipeline flow efficiency will decrease significantly with strong pulsation and noise. The fundamental frequency of the noise in the heat supply network shows a frequency doubling relationship with the natural frequency of the structure, and the rotation angle of the valve disc is negative correlation significantly with the magnitude and position of the fundamental frequency of the noise. Both of them can induce the flow-induced vibration and noise of the heat supply network, which complies with the field measurement data.