可调导叶式轴流泵压力脉动数值分析

Pressure Oscillations Prediction of Axial Flow Pump with Adjustable Guide Vanes

摘要:

轴流泵叶轮内部的压力脉动是影响其运行稳定性和叶片疲劳破坏的重要因素之一,为了研究压力脉动的特征和根源，探索压力脉动的水力优化方法，应用CFD方法模拟轴流泵内部非定常流动，在模型试验结果验证的基础上，计算了叶轮叶片和导叶表面的压力脉动，采用快速傅里叶变换进行信号处理和分析比较。研究结果表明：叶轮叶片表面压力脉动的主频是导叶通过频率，导叶表面压力脉动的主频是叶片通过频率；在小流量工况下，通过调节导叶角度可以显著降低叶轮叶片和导叶表面因动静干涉引起的压力脉动，从而降低疲劳破坏的风险。

Abstract:

Pressure oscillations in the axial flow pump impeller are associated with operational stability of the pump unit and fatigue failure of the blade. In order to obtain the characteristics and sources of the pressure oscillations and investigate the effects of adjustable guide vanes (AGV) on pressure oscillations, the CFD method based on the RANS equations and SST k-ω turbulence model was applied to simulate the unsteady flow inside the axial flow pump. The monitor points were located on the impeller blade and the guide vane. The static pressure of each survey point was recorded for 14 rotation periods. The calculated head was performed and supported by experimental data with the maximum relative error less than 4%. It indicates that the geometric model, numerical method, and simulation scheme are reasonable and reliable. Fast Fourier transformation method was used in the pressure signal processing. The main frequency of the pressure oscillations on the impeller blade is the guide vane passing frequency and the main frequency on the guide vane is the blade passing frequency, which indicates that the rotor-stator interaction between the impeller and the guide vanes is the source of the pressure oscillation in studied operating points. After adjustment of the guide vanes, the amplitudes of the pressure oscillations on both the impeller blade and the guide vane are reduced. The flow pattern with different guide vane angle was shown by the streamline, and the vortex flow was partly suppressed. It indicates that the rotor-tator interaction is improved in such operating conditions. The adjustable guide vane provides a valid solution to protect the impeller from potential fatigue failure.