Research For Flow Field And Noise Source Characteristics Of Valve In Steam Pipe

Steam pipe system is an important component of nuclear power equipment. When the steam of high temperature and pressure flows through the valve in pipe, as noise source parts, valve will produce great flow-induced noise and radial noise, which can not be neglected. In this paper, the fluid dynamic and noise source characteristics of valve is investigated by mainly using numerical simulation. The result provides some measurements in decreasing noise and designing lower noise valves.First of all, verified calculation is processed to determine the suitable computing model of throttling parts in pipe. By comparing the numerical and experimental results of several common turbulence models, standardκ-εmodel is determined to calculate the steady flow of throttling parts in pipe, and LES model is determined to calculate the unsteady flow and pressure fluctuation of throttling parts in pipe.Then,3D model of one stop valve is built by using PRO.E software, combined with CFD software FLUENT, the 3D steady and unsteady flow in valve is numerical simulated. Some flow field parameters are compared in terms of different valve opening and steam pressure drop. The internal flow field characteristic of valve is ultimately summarized.At last, time spectrum of valve's pressure fluctuation is researched. Based on this, some frequency spectrum and power spectrum density analysis is finished by using FFT transform and averaged periodogram method. The noise source characteristics of valve, such as the position of flow-induced noise,the kind of noise source and the main frequency of noise source, are further investigated.As results claim, turbulence at the throttling outlet of valve changes greatly, it acts as a main reason to produce flow-induced noise in valve. The flow-induced noise of valve in steam pipe focuses on lower frequency region. Vortex noise is the main kind of valve noise source. The change of valve opening and steam pressure drop makes great impact on producing pressure fluctuation in valve. In addition, the disturbance of valve makes the axial flow field and the pressure fluctuation perform some irregular fluctuation in downstream pipe of valve. Besides, the circumferential pressure fluctuation of valve has no conspicuous directivity.