离心泵流体激励力的研究:蜗壳部分

Fluid exciting forces on centrifugual pump part Ⅰ: force on volute

研究了叶轮转动过程中离心泵蜗壳所受流体激励力。基于CFD计算了离心泵叶轮转动过程中的瞬态内流场,而后积分得出蜗壳内表面三个方向上流体激励合力并进行频谱分析,最后运用九次多项式拟合、傅里叶级数与分段多项式拟合分别建立叶轮单周转动各向流体合力数学模型。结果表明:蜗壳所受出口方向、进口方向与垂直于进出口方向的流体激励力以叶片通过频率为基频波动,且波动幅值依次减小,波谷均出现于叶片通过蜗舌时;采用三段多项式拟合所建的数学模型与原始波形有最小的偏差,并且具有较低阶次。

Fluid exciting vibration of centrifugal pump volute was studied.Based on the results of transient fluid flow analysis via CFD simulation,three-direction orthogonal fluid exciting syntheszied forces on volute were gained by integrating the forces on interior fluid-solid interface of volute.The three-direction components of the forces were then compared among themselves both in whole transient simulation process and in sole period.Power spectrums of these forces in one period during which impeller rotates 360 degrees were analysed.The methods of nine-order polynomial curve fitting,Fourier series and multi polynomial curve fitting were used respectively to built mathematic model of three-direction single period fluid exciting forces.The result shows that,the volute suffers three-direction periodical fluid forces whose frequency is the same as the passing frequency of vanes in impeller.The direction of the first force which is perpendicular to the volute exit plane is opposite to the flowing direction and it owns the biggest amplitude fluctuation,while the direction of the second force which is perpendicular to the volute inlet plane is the same as that of the flowing.The direction of the third force,whose amplitude fluctuation is the smallest,changes periodically.It also can be known that,the peak of the second force and the trough vale of the third force in single period both appear at the location where the tip of vane passes the tangent line of volute trough,which crosses the center of impeller in the symmetrlcal plane of volute.The mathematic model by multi polynomial curve fitting can results in smallest deviation from the original signal and is of less polynomial order.