固液两相流中离心泵叶片磨损及能量损失特性分析
本文选题:离心泵 + 固相浓度 ; 参考:《兰州理工大学》2017年硕士论文
【摘要】:离心泵在农业、渔业、化工、水电厂、能源与动力工程所在的生活应用和工程应用中使用广泛,而离心泵在固液两相流中的应用主要瓶颈在于过流部件的磨损、能量损失以及泵运行稳定性。本文以导叶式离心泵为研究对象,采用标准k-?湍流模型和Mixture多相流模型进行全流道固液两相流数值模拟,在不同固相粒径(0.016mm、0.036mm、0.076mm、0.15mm)与体积分数(2%、4%、8%、12%)下,首先计算出叶轮各监测点上的磨损量,并对磨损较严重的部位进行摩擦磨损强度和碰撞磨损强度的定量计算,然后通过流体微团的相对能量转子焓(Rothalpy)值,做出从叶片前缘到出口的能量变化曲线来确定能量损失的大小,最后采用大涡模拟研究了泵流道内各监测点处的压力脉动特性,得出如下结论:1.从叶片前缘到出口,压力面上的相对速度出现先减小后增大的趋势,吸力面上的相对速度出现先增大后减小,出口处又增大的趋势。颗粒直径和固相体积分数在一定范围内变化时其对应的相对速度变化不大。2.磨损最严重的部位发生在靠近吸力面进口附近流域处,其次为叶片前缘和压力面后盖板流线出口处,压力面和吸力面出口处的磨损也较大,压力面前盖板流线头部和出口处的磨损较小。3.从叶片前缘到出口,Rothalpy值总体增大。在同一监测点上,叶片压力面上的Rothalpy值大于吸力面,叶片压力面前半段,沿叶轮径向方向流体微团逐渐获得能量。压力面后半段能量损失逐渐增大,压力面出口边流体微团获得的能量减小,出口处能量损失较大。在叶片吸力面沿叶轮径向方向,流体微团不断获得能量,靠近吸力面进口附近流域,流体微团获得的能量最小,吸力面出口边流体微团获得的能量减小,出口处能量损失较大。4.随着颗粒直径的增大,压力脉动幅值逐渐减小,固液两相介质时的压力脉动波形比清水介质时的波形出现滞后现象。压力脉动受固相体积分数变化的影响较小。
[Abstract]:Centrifugal pumps are widely used in agriculture, fishery, chemical industry, hydropower plants, energy and power engineering applications and engineering applications. The main bottleneck of centrifugal pumps in solid-liquid two-phase flow is the wear of flow components.Energy loss and pump stability.In this paper, the guide vane centrifugal pump is used as the research object.The friction and wear strength and impact wear strength of the seriously worn parts are calculated quantitatively, and then the rotorpyy values of the relative energy rotor enthalpy of the fluid microparticles are calculated.The energy change curve from the vane leading edge to the outlet is made to determine the magnitude of energy loss. Finally, the pressure pulsation characteristics at various monitoring points in the pump passage are studied by using large eddy simulation, and the following conclusions are drawn as follows: 1.From the leading edge of the blade to the outlet, the relative velocity on the pressure surface decreases first and then increases, and the relative velocity on the suction surface increases first and then decreases, and then increases at the outlet.When the particle diameter and solid volume fraction change in a certain range, the relative velocity of the particle changes little. 2.The most serious wear occurred near the drainage area near the entrance of suction surface, followed by the outlet of streamline line of blade front and back cover plate, and the wear of pressure surface and suction surface outlet was also larger.Pressure front cover streamline head and outlet wear is smaller. 3.The value of Rothalpy increases from the leading edge of the leaf to the outlet.At the same monitoring point, the Rothalpy value on the blade pressure surface is larger than that on the suction surface, and the energy is gradually obtained by the fluid microparticles along the radial direction of the impeller.The energy loss in the second half of the pressure surface increases gradually, and the energy at the outlet of the pressure surface decreases, and the energy loss at the outlet is larger.In the radial direction of the blade suction surface, the fluid microspheres continuously obtain energy. Near the inlet of the suction surface, the energy obtained by the fluid microspheres is the smallest, the energy obtained by the fluid microspheres at the suction surface exit edge decreases, and the energy loss at the outlet is larger than that at the outlet.With the increase of particle diameter, the amplitude of pressure pulsation decreases gradually, and the wave form of pressure pulsation in solid-liquid two-phase medium is hysteresis compared with that in water medium.The pressure fluctuation is less affected by the change of volume fraction of solid phase.
【学位授予单位】:兰州理工大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TH311
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