双吸离心泵空化及压力脉动的数值分析

发布时间：2018-12-16 14:32

【摘要】：双吸离心泵以其高扬程、大流量、良好的动平衡性能和抗空化性能而广泛应用于各生产领域。虽然与单吸离心泵相比双吸离心泵的抗空化性能较好,然而在实际的工作过程中,双吸泵的空化现象仍时有发生。同时,泵工作中产生的压力脉动问题不仅会造成泵体的振动和噪声,还会严重影响泵内流体的流动,从而影响泵的扬程、效率等性能,甚至破坏系统的稳定运行,减少设备的使用寿命。因此,全面认识双吸离心泵的空化性能和压力脉动特性对实际生产以及泵性能的研究具有重要的意义。本文从以下两个方面进行了研究分析:首先,对双吸泵在不同的工况下进行空化性能模拟,随着泵进口总压的下降,叶轮叶片吸力面前缘先形成低压区并逐渐向叶轮出口方向扩展,且低压区在叶片间不同流道内的分布不均匀;空泡最先产生在叶片进口稍后位置靠近前盖板处,前盖板的空化程度明显大于后盖板;空化扬程的下降与空化尾迹区的漩涡有重大关系,漩涡引起的能量损失是导致扬程急剧下降的主要因素。其次,设计了四种交错角度的叶轮并进行非定常计算,通过从时域和频域等对监测点在某一个计算周期的压力变化性能分析,发现双吸泵蜗壳中主要的压力脉动频率为叶片通过频率及其倍频,叶轮交错45°时双吸泵的压力脉动幅值显著减小,说明该双吸泵的最佳叶轮交错角为45°,并从流体流动状态的角度对这一结论进行了验证。
[Abstract]:Double suction centrifugal pump is widely used in various fields for its high lift, large flow rate, good dynamic balance and cavitation resistance. Although the anti-cavitation performance of double-suction centrifugal pump is better than that of single-suction centrifugal pump, the cavitation phenomenon of double-suction pump still occurs in practice. At the same time, the pressure pulsation will not only cause the vibration and noise of the pump body, but also seriously affect the flow of fluid in the pump, thus affecting the performance of the pump, such as lift, efficiency, and even destroy the stable operation of the system. Reduce the service life of the equipment. Therefore, it is of great significance to understand the cavitation performance and pressure pulsation characteristics of double suction centrifugal pump for practical production and research of pump performance. In this paper, the following two aspects are studied and analyzed: firstly, the cavitation performance of the double suction pump is simulated under different operating conditions, with the decrease of the total inlet pressure of the pump. The front edge of suction of impeller first forms low pressure area and gradually extends to the outlet of impeller, and the distribution of low pressure region in different flow channels between blades is not uniform. The cavitation occurs at the later position of the blade inlet near the front cover plate, and the cavitation degree of the front cover plate is obviously greater than that of the rear cover plate. The decrease of cavitation head is closely related to the vortex in cavitation wake region, and the energy loss caused by the vortex is the main factor leading to the sharp decline of the head. Secondly, four kinds of impellers with staggered angles are designed and calculated unsteady. The performance of pressure variation of monitoring points in a certain period is analyzed from time domain and frequency domain. It is found that the main frequency of pressure pulsation in the volute of double suction pump is blade passing frequency and its double frequency, and the amplitude of pressure fluctuation of double suction pump is significantly reduced when the impeller is staggered 45 掳, which indicates that the optimum interleaving angle of impeller is 45 掳. The conclusion is verified from the point of view of fluid flow state.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH311

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