转速控制对水力机械模型试验精度的影响

模型试验是国际普遍采用的检验和改进水力机械设计的主要方法.文中介绍了水力机械模型试验转速控制方式,讨论了模型试验误差产生的原因、种类和计算方法.结合某模型试验台转速控制对试验精度产生的影响,进行了分析,并采取了措施,保证了试验精度.     

利用模型试验台研究管道输送阻力特性

随着管道输送固体物料的广泛应用,水力输送技术的研究越来越受到重视。本文介绍了一台操作简便、自动化程度高的模型试验台,并利用该试验台对管道输送中阻力损失特性进行研究。     

白市水电站水轮机模型验收试验

在对列宁格勒金属工厂水力试验台进行介绍的基础上,介绍了白市水电站水轮机模型转轮验收试验的主要项目和具体过程,并对试验结果和PO55转轮性能进行了分析评价.     

基于改进BP神经网络的水力机械特性数据处理

针对现有的水力机械特性数据处理方法的不足,应用一种改进的BP算法--Levenberg-Marquardt反向传播方法对水力机械特性数据进行处理,并将改进的BP算法与元胞自动机理论所建立模型的计算结果进行比较.结果表明,改进的BP神经网络算法能有效地处理水力机械特性数据及真实反映水力机械特性,计算精度高,完全可应用于水力机械控制和优化运行.     

多机型柴油机缸盖气道试验台设计

本文介绍了一种多机型柴油机缸盖气道试验台的设计,描述了其机械结构、功能原理及控制算法。该气道试验台能够通过简单的夹具更换,适用于各种柴油机缸盖气道的性能测试。同时该气道试验台具有高度的自动化控制功能,能够大幅提高气道试验的效率和精度。     

多机型柴油机缸盖气道试验台设计

本文介绍了一种多机型柴油机缸盖气道试验台的设计,描述了其机械结构、功能原理及控制算法。该气道试验台能够通过简单的夹具更换,适用于各种柴油机缸盖气道的性能测试。同时该气道试验台具有高度的自动化控制功能,能够大幅提高气道试验的效率和精度。     

不同空泡动力学模型在空泡振荡预测中的应用探讨

空泡动力学问题一直是水力机械领域关注的热点问题之一.空泡动力学的研究起源于水力机械的空蚀现象,弄清空泡运动(主要指单空泡生长、发展和溃灭过程)对空蚀机理研究有重要意义.本文探究了Rayleigh-Plesset(R-P)模型、Gilmore模型和Keller-Miksis(K-M)模型在预测空泡振荡过程中的应用,重点关...     

双向式油压减振器试验台

介绍一种新型双向式油压减振器试验台。试验台由机械部分、电气部分和计算机测控系统组成。采用了交流电机变频调速 ,不仅简化了机械部分的设计 ,同时调速范围宽 ,灵活性好 ,可适应多种型号减振器试验的要求。计算机测控系统由计算机、传感器与信号调理、数据采集与控制接口等组成 ,工作原理简明、试验精度高、结构简单、可靠性好、使用方便。     

水力机械流动分离与损失相关性的工程模型

分离的产生严重影响水力机械的流动特性，流动分离与水力损失密切相关，为了在设计中确定流动分离损失。该文通过利用死水区假设的似计算分离区的大小，提出了一和种近似计算分离损失的方法。同时，给出了一种利用进出口参数来确定转轮内部流动分离的分离尺度和起始位置的工程模型。研究结果表明，流动发生分离后，在流向下游的过程中分离区不断扩大，流动分离的起始位置对转轮出口的分离尺度及水力损失有很大的影响。     

水力风力机械抛煤机链条炉

对水力风力机械抛煤机链条炉的试验研究表明，水力风力机械抛煤机链条炉具有抛煤更加均匀，飞灰机械不完全燃烧损失小及炉膛出口空气过量系数低等优点。     

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。     

Seasonal performance rating of heat pump water heaters

Seasonal performance evaluation methods for water heaters are reviewed and an experimental method for rating air-source heat pump water heaters is presented. The rating method is based on measured heat pump performance during heat-up operation of particular products rather than a generic simulation model of heat pump performance. The measured performance is used in a correlation model of the heat pump unit in an annual load-cycle system performance simulation based on the TRNSYS simulation package.     

水泵、节温器综合试验台的设计与应用

本文介绍了水泵、节温器综合试验台的设计与应用,论述了本试验台的设计依据、主要特点、构成及功能、实际应用等内容。本综合试验台的创新点在于：在该试验台上不仅可以完成发动机水泵的性能试验,还可以完成节温器性能和可靠性试验;而且更好的模拟了节温器在发动机上的实际使用状况,完美的将两者结合在一起,利用被试水泵作为供水泵完成了相配套的节温器试验内容。     

Small-scale irrigation with photovoltaic water pumping system in Sahara regions

Several photovoltaic applications, specially the water pumping systems, are installed to contribute in the socio–economic development in Algerian Sahara. About sixty pumps are installed in remote regions to supply water for drinking and irrigation. The centrifugal pumps present the state-of-the-art for most applications. This paper presents the electrical and hydraulic performance of a surface centrifugal pump versus total water heads and versus a size of PV array. Also the area irrigated by this solar surface pump is calculated under Sahara climate conditions for four crops, namely wheat, potatoes, tomatoes and sunflowers. These were selected to meet with food standards of the sites. Two application sites were chosen to test the developed model. The first is Bechar station and the second is Tamanrasset station. In both, the recorded solar radiation data were used. The results, which are illustrated by tables and curves, are analysed. The analysis of the performance concluded that this surface pump is suitable for installation in the Sahara regions with low water head.     

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.     

Performance of a gas engine driven heat pump for hot water supply systems

The present work aimed at evaluating the experimental performance of a gas engine heat pump for hot water supply. In order to achieve this objective, a test facility was developed and experiments were performed over a wide range of ambient air temperature (10.9-25.3 °C), condenser water inlet temperature (33-49 °C) and at two engine speeds (1300 and 1750 rpm). Performance characteristics of the gas engine heat pump were characterized by water outlet temperatures, total heating capacity and primary energy ratio. The reported results revealed that hot water outlet temperature between 35 and 70 °C can be obtained over the considered range of the operating parameters. Also, total heating capacity and gas engine heat recovery decrease by 9.3 and 27.7%, respectively, while gas engine energy consumption increases by 17.5% when the condenser water inlet temperature changes from 33 to 49 °C. Total heating capacity, gas engine heat recovery and gas engine energy consumption at ambient air temperature of 25.3 °C are higher than those at ambient air temperature of 10.9 °C by about 10.9, 6.3 and 1.5% respectively. Moreover, system primary energy ratio decreases by 15.3% when the engine speed changes from 1300 to 1750 rpm.     

Moderately high temperature water source heat-pumps using a near-azeotropic refrigerant mixture

A ternary mixture of R124/R142b/R600a, named HTR01, for moderately high temperature heat pumps, was developed. Tests of material compatibility and oil miscibility showed that the mixture could be used with a R22 compressor in an HTR01 heat-pump system. A 2.92 kW moderately high temperature water source heat pump system was set up with HTR01 as the refrigerant to study the system performance with HTR01. Then, a 300 kW moderately high temperature water source heat pump system was built with HTR01 as the refrigerant to test the performance with a geothermal hot water source. The test showed that the condenser outlet water temperature could reach and hold on about 90 °C with a high coefficient of performance.     

Measurement of the performance of domestic air-to-air heat pumps

It is desirable to test heat pumps over the whole range of conditions under which they will be used. A test facility built at BRE is described in which these conditions may be readily adjusted in a controlled manner, the test procedure for a heat pump unit being carried out in a relatively short time. the heat pump itself is utilized to attain conditions of lower temperature and humidity than ambient. The problems of measuring heat transport in air streams are outlined and ways of overcoming them are given. Particular attention should be given to mixing the air streams. Various aspects of instrumentation of such a test facility are discussed.