大型双吸离心泵转子振动分析

发布时间：2018-04-04 17:25

本文选题：离心泵　切入点：内部流场　出处：《兰州理工大学》2011年硕士论文

【摘要】：双吸离心泵广泛应用于灌溉工程、城市给排水、跨流域调水等领域,是一种重要的水力机械。它的叶轮是由两个背靠背的叶轮组合而成,在同样的叶轮外径下,其流量可增大一倍。双吸泵的形状对称,两侧的轴向力互相抵消,平衡性比较好,由于采用中开结构,可以打开泵盖检修泵内各零件,检修极为方便。而且这种泵的耐气蚀性能也比较好,但在运行中常出现一些故障,如泵轴与轴套接触的表面以及轴套端面等处发生疲劳破坏,从泵启动到打开出口阀门之间密封环常发生抱轴现象,泵体密封环和叶轮密封环粘接,必须加大密封环间隙才能正常启动.而密封环间隙加大就会降低容积效率,影响泵站的经济运行。这些问题在大型泵站运行时有发生,严重影响泵站的安全正常运行,需要从根本上加以解决。通过分析离心泵转子的振动现象发现,离心泵工况变化会造成泵内流场结构改变,叶轮所受载荷周向分布不均,因此在叶轮径向产生径向力,引起振动及噪声.叶轮上的径向力可分为稳态作用力和瞬态作用力,其中稳态力作用于叶轮转子上会使叶轮出现偏心,瞬态力会引起离心泵转子的振动。因此,研究叶轮的稳态和瞬态作用力是非常有必要的。本文提出了数值模拟计算离心泵稳态和瞬态作用力的方法,建立了叶轮径向力的计算模型。以1200S56型泵为例,应用Fluent软件分别对离心泵不同流量下的内部流场进行了三维稳态数值模拟,给出了吸水室、叶轮和压水室静压和速度的分布规律,应用流体对叶轮作用力计算模型,计算了在不同工况下的稳态作用力.又对离心泵的内部流场在0.6Q流量下进行了三维非稳态数值模拟,得出了瞬态作用力分量Fy、Fz随时间t周期变化的曲线。本文的主要研究成果如下: 1.在输送清水时,双吸离心泵叶轮从进口到出口,压力经历了先降低后升高的过程,相同半径处,叶片工作面压力较背面压力高;双吸离心泵叶轮从进口至出口,速度逐渐增加,相同半径处,速度从叶片背面到叶片工作面逐渐减小。叶轮速度场、压力场有轻微分布不均现象,这与采用半螺旋型吸水室的双吸离心泵特殊结构有关。 2.稳态作用力在不同工况下的计算值变化趋势跟实验数据基本一致,离心泵偏离设计工况时稳态作用力会显著增加;在0.6Q流量下,瞬态径向力分量随时间周期变化的曲线分别为近似余弦、正弦曲线。 3.应用ANSYS Workbench对双吸离心泵叶轮转子进行了模态分析,并得到其1~6阶模态振动频率。
[Abstract]:Double suction centrifugal pump is widely used in irrigation works, city water supply and drainage, inter basin water transfer and other fields, is a kind of important hydraulic machinery. It is composed of a combination of two impeller impeller back into the same impeller diameter, the flow rate can be doubled. The shape of the said double suction pump the axial force, on both sides of the offset balance is better, because the open structure, can open the pump cover parts of pump maintenance, maintenance is convenient. And the corrosion performance of the pump is relatively good, but in the operation often appear some faults such as the pump shaft and the shaft sleeve of the contact surface and the sleeve at the end of fatigue failure, open the outlet valve between the sealing ring axle phenomenon often occurs from the start to the pump, pump seal ring and impeller sealing ring bonding, must increase the clearance of seal ring can be normally started. And the seal ring will reduce the gap to increase volumetric efficiency. The economic operation of the pumping station. These problems occur during the operation of large pumping stations, which seriously affect the safe and normal operation of the pumping stations, and need to be fundamentally solved.
Through the analysis of the phenomenon of vibration of rotor in centrifugal pump, centrifugal pump working condition will cause the change the flow structure in the pump impeller circumferential load distribution is uneven, resulting in radial impeller radial force, causing vibration and noise. The radial force on the impeller can be divided into steady-state and transient force force, the force acting on the steady state the impeller rotor makes the impeller eccentric, transient force will cause the vibration of centrifugal pump rotor. Therefore, steady-state and transient force of the impeller is very necessary. This paper presents a numerical simulation method for calculating steady-state and transient force of centrifugal pump, impeller radial force calculation model was established. Using 1200S56 type pump an example, using Fluent software respectively, the 3-dimensional simulation of the internal flow field of centrifugal pump under different flow, gives the distribution of suction chamber, impeller and volute velocity and static pressure should be. The calculation model of the impeller with fluid force, steady force under different conditions were calculated. And the internal flow field of centrifugal pump in 0.6Q flow was numerically simulated the unsteady three-dimensional, the transient force components Fy, Fz changes with the time of the T cycle curve. In this paper, the main research results are as follows:
1. in the transport of water, double suction centrifugal pump impeller from inlet to outlet pressure, undergoes a process of first decreased and then increased, the same radius, the blade pressure is high back pressure; double suction centrifugal pump impeller from the inlet to the outlet, the speed gradually increased, the same radius, speed from the back of the blade to blade the working surface decreases gradually. The impeller velocity field, pressure field slightly uneven distribution of the phenomenon, and the semi spiral suction chamber of double suction centrifugal pump with special structure.
The calculation of 2. steady state force in different conditions the value changes with experimental data are basically the same, the centrifugal pump off design conditions of steady state force will increase significantly; in the flow of 0.6Q, transient radial force components change with time cycle curve respectively approximate cosine, sine curve.
3. the modal analysis of the impeller rotor of a double suction centrifugal pump is carried out by using ANSYS Workbench, and the modal vibration frequency of its 1~6 order is obtained.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH311

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