基于双向流固耦合的低比转速离心泵非定常流动及振动特性分析

发布时间：2018-08-19 14:27

【摘要】：低比转速离心泵具有输送介质流量小、扬程高等特点,广泛应用于石油化工、制药和电力等工业领域中。但泵运行过程中会出现振动,这将引起泵的损坏,降低性能,减少使用寿命,同时还将产生噪声。因此提高离心泵的平稳运行至关重要。泵内非定常流动产生的水力激励力是导致离心泵不稳定运行的主要原因之一,泵内部流体非定常流动造成的振动将严重影响离心泵的安全稳定运行。本文运用CFD软件和FEM软件进行耦合计算,研究了低比转速离心泵内非定常流动与转子系统振动之间的关系,主要研究内容如下:(1)运用Pro/E软件建立低比转速离心泵全流场三维模型,包括前后盖板间隙与口环间隙,并使用ANSYS ICEM生成网格。基于SST(Shear Stress Transport)k-ω湍流模型对离心泵内部流场进行非定常计算,分析了离心泵内压力、速度和轴向涡流的分布情况。(2)通过双向流固耦合计算和非耦合计算获得蜗壳上的压力脉动,与实验结果进行比较,发现两种模拟的结果与实验结果都很接近,变化规律一致,在一个周期内出现8个波峰,波峰数与叶轮叶片数相同。(3)为了了解非定常流动下径向力的变化规律,对叶轮上的径向力和单个叶片上的径向力进行分析。结果发现:叶轮上的径向力周期变化,随着流量增加叶轮上的径向力逐渐增大;单叶片上的径向力在叶片经过隔舌时会发生突变,流量越小变化越明显。(4)对转子系统进行模态分析,得到前十阶模态的固有频率和模态振型图;并分析了叶轮在不同流量下的叶轮振动位移,随着流量增加叶轮的振动位移增加,在小流量下振动位移不规则。
[Abstract]:Low specific speed centrifugal pump is widely used in petrochemical, pharmaceutical and power industries because of its small flow rate and high head. However, vibration will occur during the operation of the pump, which will cause damage to the pump, reduce performance, reduce service life, and also produce noise. Therefore, it is very important to improve the smooth operation of the centrifugal pump. Hydraulic excitation force produced by unsteady flow in pump is one of the main reasons leading to unsteady operation of centrifugal pump. Vibration caused by unsteady flow in pump will seriously affect the safe and stable operation of centrifugal pump. The main research contents are as follows: (1) Using Pro/E software to build a three-dimensional model of the whole flow field of low specific speed centrifugal pump, including the gap between front and rear cover plate and orifice ring, and using ANSYS ICEM to generate grid. Based on the SST (Shear Stress Transport) k-_turbulence model, the unsteady flow field in the centrifugal pump was calculated and analyzed. The distribution of pressure, velocity and axial eddy current in the centrifugal pump was studied. (2) The pressure pulsation on the volute was obtained by two-way fluid-solid coupling calculation and uncoupled calculation. Comparing with the experimental results, it is found that the two simulation results are very close to the experimental results, and the variation law is consistent. There are eight peaks in one cycle, and the number of peaks and impeller blades appear. (3) In order to understand the variation of radial force under unsteady flow, the radial force on the impeller and the radial force on a single blade were analyzed. (4) The natural frequencies and mode shapes of the first ten modes are obtained by modal analysis, and the vibration displacement of the impeller under different flow rates is analyzed. The vibration displacement of the impeller increases with the flow rate, and the vibration displacement is irregular at small flow rates.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH311

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