几种水机常用金属材料的冲蚀磨损性能研究

研究了在水力机械中普遍应用的铸铁(HT200)、中碳结构铸钢(40#)、不锈钢(1Cr18Ni9Ti)和高铬铸铁(KmTBCr26)4种材料的冲蚀磨损规律,得出了材料的冲蚀磨损率随磨损时间、冲蚀速度、磨粒浓度和粒径变化的规律,同时根据观察材料冲蚀磨损表面形貌探讨了其冲蚀磨损机理.结果表明:材料的冲蚀磨损性能受到材料基本机械性能的控制,其中高硬度材料的抗冲蚀性能较好,在相同试验条件下其磨损率由大到小排列顺序为HT200＞40#＞1Cr18Ni9Ti＞KmTBCr26;4种材料的冲蚀磨损率随磨粒粒径、浆料浓度和磨粒冲击速度的变化规律基本一致,当磨粒粒径小于425 μm时,磨粒粒径对KmTBCr26和1Cr18Ni9Ti的磨损率影响很小;金属材料的组织结构对材料的冲蚀磨损性能和机理影响较大,其中KmTBCr26和1Cr18Ni9Ti的冲蚀磨损机理以脆性断裂、破裂及颗粒脱落为主,而HT200和40#的冲蚀磨损机理以选择性切削式冲蚀磨损为主.     

A Thermodynamic Cavitation Model for Cavitating Flow Simulation in a Wide Range of Water Temperatures

A thermodynamic cavitation model is developed to simulate the cavitating water flow in a wide temperature range. The thermal effect on bubble growth during cavitation is introduced in the developed model by considering both pressure difference and heat transfer between the vapor and liquid phase. The cavitating turbulent flow over a NACA0015 hydrofoil has been simulated at various temperatures from room temperature to 150°C by using the present cavitation model, which has been validated by the experimental data. It is seen that the thermodynamic effects of cavitation, vapor depression and temperature depression are much more predominant in high temperature water compared with those in room temperature water. These results indicate that the proposed thermodynamic cavitation model is reasonably applicable to the cavitating water flow in a wide temperature range.     

离心式叶轮中低浓度固体颗粒分布的研究

离心式叶轮中低浓度固体颗粒分布的研究许洪元，吴玉林，戴江，宋益群，王琳（清华大学水电系北京１０００８４）关键词：叶轮，两相流，颗粒分布一、前言固液离心泵在工业上得到广泛应用。其内部流动机理的研究有很大实际意义。已有多人进行了离心叶轮中固体颗粒运动轨迹...     

离心式渣浆泵叶轮磨损规律研究

在实验室条件下对离心式渣浆泵叶轮的磨损规律进行了研究，并对泵轮叶片间流道的颗粒运动轨迹进行数值模拟。探讨了磨粒浓度、泵转速、叶片几何参数、运行时间及磨粒粒径对泵轮磨损的影响。研究表明：叶片的磨损强度与泵轮转速呈５次方关系，叶片进口角对磨损强度影响明显，出口角对磨损强度影响不大，研究结果对渣浆泵的设计具有重要的参考价值。     

A Three-Component Model Suitable for Natural and Ventilated Cavitation

A three-component model based on mass transfer equation is proposed to simulate both the natural and ventilated cavitations. In the present cavitation model, the content of nuclei in the local flow field is updated synchronously, and is coupled with the Rayleigh-Plesset equation so as to capture the cavity development. The proposed model is applied for simulating the cavitating flow around a super-cavitating vehicle in different cavitation conditions. In the ease of the natural cavitation simulation, the predicted cavitation characteristics including the cavity length and cavity diameter agrees fairly well with the analytical results. In the case of the mixed cavitation simulation, the gas ventilation obviously influences the development of cavity. With the increase of the gas ventilated rate, the natural cavitation is suppressed remarkably, and a super cavitation is formed even at a relatively larger natural cavitation number.     

离心泵叶轮中固体颗粒运动轨迹计算

为了研究固体颗粒在离心泵叶轮中的运动规律,利用有限元法对低比转数离心泵叶轮的S_1流面的流动进行了流场计算.在此基础上用拉格朗日法计算颗粒的轨迹,计算结果能与实验结果相吻合.     

基于BVF流场诊断的高比转速离心泵叶轮优化

高比转速离心泵由于流道较宽,叶片扭曲较大,基于一元理论的传统离心泵叶片设计方法并不适用。本文对一种采用速度系数法设计的高比转速(n_s=271)潜水泥泵叶轮进行了泵内三维流场的数值模拟;根据泵内流动计算结果,基于涡动力学的边界涡量流(BVF)诊断方法,通过调整叶片设计参数和轴面流线对泵的叶轮进行了优化。结果表明;优化后的泵水力性能得到了较大改善;借助BVF的流场诊断方法可有效地捕捉到泵内不良流动的根源,从而为改善叶片设计指引方向。     

渣浆泵的固液流设计原理

渣浆泵广泛应用于矿山、冶金、电力、煤炭、水利、交通等行业,进行尾矿、精矿、煤泥和砂砾等固体物料的水力输送。按清水理论设计的渣浆泵在抽送固液混合流体时效率普遍偏低,磨蚀严重,造成能源和设备的大量浪费。 本文应用固液流动理论,给出固液渣浆泵(简称固液泵)的基本方程式,应用于离心泵