水喷射技术在冷凝水回收系统中的应用

高温冷凝水回收是工业企业节能领域常见的余热回收工艺,水泵汽蚀和闪蒸汽的处理是冷凝水回收利用的核心问题,利用水喷射技术是一种实用的解决办法,采用该项技术的密闭式凝结水回收系统成功推广应用了20余年。     

锅炉给水泵进口有效汽蚀余量的计算

水泵汽蚀余量由于叶轮机械中流体运动的复杂性,很难从理论上计算出流场中何处可能出现汽蚀,再加上汽蚀现象不仅仅取决于流体的流动特性,还取决于流体本身的热力学性质,所以,更难于从理论上提出汽蚀发生的判据。本文从实际应用角度出发,针对锅炉给水泵有效汽蚀余量进行校核计算,以满足工程安全运行需要。     

对水泵汽蚀的探讨

矿井排水设备的经济运行 ,直接关系到煤矿的经济效益。水泵汽蚀对排水效率有重要影响 ,分析了水泵产生汽蚀的原因及危害 ,提出了解决汽蚀的相应措施。     

离心水泵的汽蚀现象分析及其对策

离心水泵在输送高温冷凝水时发生的汽蚀现象,是导致高温冷凝水无法直接回收利用的技术性难题.本文对离心水泵汽蚀现象产生的原因、危害及其造成的能源和水资源的浪费进行了简要分析,并提出了一种解决汽蚀问题的办法.     

实验室铸铝水泵汽蚀故障原因的排查与优化

为解决某发动机铸铝水泵零部件耐久试验中发生的汽蚀问题,首先对水泵开展汽蚀余量的分析.其次对故障水泵与成熟产品进行仿真的对比,包括:流场、流速、空化区域;并基于仿真结果,分析水泵设计是否存在缺陷.最后对试验装置进行对比,发现汽蚀故障是由于水泵厂家耐久试验台架管路布置不规范导致.通过开展水泵性能及汽蚀余量实测,验证仿真结论,确认故障发生的根本原因,为同类问题提供排查思路及解决办法.     

珠海电厂给水泵汽蚀余量的校核计算

利用ＡＳＭＥ的“甩负荷时给水泵汽轮余量的分析”理论,校核了珠海电厂容量７００ＭＷ机组在最恶劣工况即阀全开跳机工况时的给水泵汽蚀余量,并在甩负荷时,进行了试验验证,结果表明：给水泵吸入口系统设计是合理的。     

冷凝水回收系统的改造及效益分析

本文针对离心水泵输送高温冷凝水时存在的汽蚀问题，提出了高温冷凝水的防汽蚀密闭回收方案，并对高温冷凝水的防汽蚀密闭回收产生的经济效益进行了分析。     

锅炉房水泵吸水高度及灌注水头高度探讨

通过模拟计算,描述水泵吸水口轴线与液面之间的相对位置受安装地的大气压、水温、水泵必须汽蚀余量、水泵吸水管路压降四方面因素影响。通过简述一个案例,介绍当采用大气式热力除氧器时,计算锅炉给水泵灌注水头高度需要考虑的因素。     

工业回收冷凝水泵防汽蚀改造

在工业生产过程中，为了节能降耗，需要回收蒸汽冷凝水。由于冷凝水是饱和水，在用泵输送回用过程中易发生汽蚀，影响泵的安全稳定运行，有时不得不停止运行，就地排放冷凝水，这既损坏了设备，又浪费了能源。利用喷射增压的原理，可以解决泵的汽蚀问题。     

水冷摩托车发动机水泵汽蚀现象及改进设计

从理论上分析水冷摩托车发动机冷却水泵产生汽蚀的原因、影响因素以及改进措施，探讨了提高抗汽蚀性能的叶轮设计方法，并简介微机设计步骤。     

凝结水旁路调频下除氧器暂态安全性计算

凝结水旁路参与调频是一种增强机组调频能力的有效方法,但调频过程中除氧器暂态特性可能会受到一定的影响,从而影响前置泵的运行安全。本文介绍了凝结水旁路参与调频的原理和方案,提出了此过程中除氧器前置泵暂态安全性计算的必要性。基于三点假设,构建了除氧器中凝结水焓值和工作压力、前置泵入口给水焓值和入口汽化压力、前置泵入口温度和有效汽蚀余量的计算模型。结果表明:40%凝结水旁路开度下前置泵有效汽蚀余量最大会下降13.75 m,对安全性造成威胁。该研究为凝结水旁路参与调频的可行性提供理论基础。     

脉冲液体射流泵能量平衡的数值研究

运用能量平衡分析原理,根据脉冲液体射流泵主要流动部件的能量损失压力比公式,利用脉冲液体射流泵性能数值计算模块,对脉冲液体射流泵能量平衡进行了数值研究,分析了主要流动部件的能量损失变化及其对脉冲液体射流泵性能的影响,并与恒定液体射流泵的能量损失压力比、性能及效率进行了对比。结果表明,脉冲射流是提高射流泵传能、传质效率的有效途径。     

Investigation of coolant flow distribution and the effects of cavitation on water pump performance in an automotive cooling system

Cavitation is a well‐known phenomenon that causes performance losses in all kinds of hydraulic machinery, including automotive water pumps. The present study uses a coolant flow test rig to investigate cavitation in water pumps. The coolant flow rate was measured for various coolant temperatures and compositions. This study validates that cavitation occurs during the coolant warm‐up period, in which coolant temperature is typically below 80°C. Cavitation was also related to a drop in the water pump inlet pressure and driving torque. Based on the results from this study, it can be concluded that cavitation is affected by coolant temperature, engine speed, and coolant composition. Furthermore, it is found that the use of an electric water pump is effective for minimizing the pressure drop and driving loss of the pump. Copyright © 2008 John Wiley & Sons, Ltd.     

Turbo-pump with Isolated Two Stage Impellers for Future Rocket Engine （Trial to Drive Impellers Independently）

To suppress the cavitation in the impellers and to make the turbo-pump lives longer, the inducer was separated from the main impeller and both impellers were driven independently. The performance of the pump and the flow conditions around the impellers were investigated experimentally and the following results were obtained. （1）The main impeller contributes to the flow interaction between the inducer and the main impeller. （2）The rotational speeds of both impellers can be controlled independently in order to suppress simultaneously the cavitation not only in the main impeller, but also in the inducer.     

水喷射泵在供热系统中的应用

水喷射泵不仅具有结构简单、无活动部件、节约电能、安装方便等优点,且可以消耗供暖用户的＂富余＂压头,提高供热外网的水力稳定性,增大供暖末端用户的资用压差,所以,水喷射泵在供热系统中得到越来越多的使用。叙述了水喷射泵在供热系统中,在高低区直连系统、一、二次网直连系统及二次管网上的应用。     

柴油机喷孔内部空化效应的可视化实验研究

柴油机喷孔内空化现象显著影响燃油雾化质量.针对目前广泛应用的VCO型喷嘴,设计大尺度透明喷嘴稳态实验系统,全面研究了无量纲数、雷诺数、喷嘴射流参数和结构参数对喷嘴内空化过程的影响.结果表明,空化数对空化剧烈程度影响显著,雷诺数对空化剧烈程度影响小于空化数;射流参数直接影响流体流动状态,增大入口压力、减小出口压力和针阀升程能使喷孔内的空化现象显著增强;结构参数决定喷孔内流动形式,增大喷孔倾角、直径和长径比,采用入口圆角等措施会抑制空化的产生.     

Computational Cavitation Flows at Inception and Light Stages on an Axial-Flow Pump Blade and in a Cage-Guided Control Valve

Cavitation flows induced around an axial-flow pump blade and inside a high pressure cage-type valve are simu-lated by a two-dimensional unsteady Navier-Stokes analysis with the simplest treatment of bubble dynamics.Thefluid is assumed as a continuum of homogeneous dispersed mixture of water and vapor nuclei.The analysis isaimed to capture transient stages with high amplitude pressure change during the birth and collapse of the bubbleespecially at the stage of cavitation inception.By the pump blade analysis,in which the field pressure is moderate,cavitation number of the inception and locations of developed cavitation are found to agree with experimental re-suits in a wide flow range between high incidence and negative incidence.In the valve flow analysis,in which thewater pressure of 5MPa is reduced to 2MPa,pressure change responding to the bubble collapse between the vaporpressure lower than 1 KPa and the extreme pressure of higher than 10~4 KPa is captured through a stable computa-tion.Location of the inception bubble and pressure force to the valve plug is found agree well with the respectiveexperimental features.     

Time-dependent leak behavior of flawed Alloy 600 tube specimens at constant pressure

Leak rate testing has been performed using Alloy 600 tube specimens with throughwall flaws. Some specimens have shown time-dependent leak behavior at constant pressure conditions. Fractographic characterization was performed to identify the time-dependent crack growth mechanism. The fracture surface of the specimens showed the typical features of ductile fracture, as well as the distinct crystallographic facets, typical of fatigue crack growth at low ΔK level. Structural vibration appears to have been caused by the oscillation of pressure, induced by a high-pressure pump used in a test facility, and by the water jet/tube structure interaction. Analyses of the leak behaviors and crack growth indicated that both the high-pressure pump and the water jet could significantly contribute to fatigue crack growth. To determine whether the fatigue crack growth during the leak testing can occur solely by the water jet effect, leak rate tests at constant pressure without the high-pressure pump need to be performed.     

磨料射流技术去内孔毛刺的应用研究

精密零件内孔的去毛刺、抛光问题是劳动力最为集中而又最难控制的部分，也是精密零件生产全自动化中难以克服的障碍。通过磨料射流技术在喷油嘴喷孔和喷油器体高压油道的加工实践，历时两年，研制成功了一种基于电磁阀控制加压与供料及双料罐循环使用的磨料浆体射流多工位加工机床，可广泛应用于内燃机曲轴冷却油道、工程机械液压回路、柴油机燃油喷射系统中油泵壳体的高低压油路、喷油器体的高压油道、喷油嘴的喷孔、共轨系统中共轨管高压腔及接头回路、单体电体泵头高压油腔、电磁阀油孔的光整加工，开创了磨料射流技术去内孔毛刺的新方法。     

磨料射流技术去内孔毛刺的应用研究

精密零件内孔的去毛刺、抛光问题是劳动力最为集中而又最难控制的部分,也是精密零件生产全自动化中难以克服的障碍。通过磨料射流技术在喷油嘴喷孔和喷油器体高压油道的加工实践,历时两年,研制成功了一种基于电磁阀控制加压与供料及双料罐循环使用的磨料浆体射流多工位加工机床,可广泛应用于内燃机曲轴冷却油道、工程机械液压回路、柴油机燃油喷射系统中油泵壳体的高低压油路、喷油器体的高压油道、喷油嘴的喷孔、共轨系统中共轨管高压腔及接头回路、单体电体泵头高压油腔、电磁阀油孔的光整加工,开创了磨料射流技术去内孔毛刺的新方法。