Research On Noise And Vibration Of Multi-stage Depressed Drain Valve And Pipeline

This paper is completed with the support of the national natural science fund(number: 5156012). Because of the complex internal structure of high pressure-drop steam trap, the valve trim has a characteristic of the throttle. During the opening and closing process and operating conditions, the fluid lead to pulsation and vortex,inducing fluid excitation and strong noise. Aiming at the problem of vibration and noise of steam trap, this paper focus on high pressure-drop multistage steam trap and valve-regulating pipeline, and makes a series of researches as following:(1) The causes and hazards of vibration and noise of high pressure-drop trap were introduced. Based on research progresses on the trap vibration and noise, the necessity of optimizing valve throttle internals was put forward for inhabiting vibration and noise.(2) Model structure, working principle and design process of high pressure-drop multistage trap were introduced. The steady-state flow field numerical simulation of high pressure-drop multistage trap and valve-controlled piping was carried out.Setting steady-state simulation results as initial conditions, transient simulation was carried out, which was the foundation of numerical calculation of vibration and noise.(3) Based on fluid-solid coupling theory, 4-equation model of water hammer and vibration about valve and piping was established. By finite difference method, the4-equation model were converted into programmable finite differential equations.Time-domain curve of medium pressure and pipe axial force were gained by Matlab and the interact with each other was analyzed. Combining CFD(Computational Fluid Dynamics) software and LMS Virtual.Lab, FFT(Fast Fourier Transform) and DBEM(Direct Boundary Element Method) were used to obtain vibration acceleration level of the outer surface of trap. The effects of different pressure-drop stages and pore diameter on throttle sleeve were compared, which provided reference for vibration inhibition research.(4) According to the research object in this paper, flow-induced sound source was analyzed, and the main effects on sound power were gained by deducing sound power. Combining CFD software and LMS Virtual.Lab, DBEM was used to simulate flow-induced noise of high pressure-drop trap to obtain the sound field pressure cloud and spectral characteristic curves. The effects of different pressure-drop stages and pore diameter on throttle sleeve were compared, which provided reference for noiseinhibition research.The above researches provide a reference for optimizing and designing valve internals of high-pressure-drop trap, and provide a method for inhibiting flow-induced vibration and noise of trap.