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In the hydraulic transition process of remote and up-and-down water supply project, vaporization and column separation easily occur, which may cause water hammer damage to the pipeline. In this paper, the principle and boundary conditions of air valve and one-way surge tank were analyzed. The numerical simulation of hydraulic transition process was conducted on the calculation model of gas-liquid...
The dynamic characteristics of the sliding bearing have great influences on the vibration and stability of the rotor-bearing coupled system. This study focus on a water lubricated bearing which supports the vertical rotor in a test facility. This rotor system is designed with maximum rotational speed of 5000 rpm and used to study the influence of water bearing on the rotor dynamics. Based on the unsteady...
In power generation plants, irrigations, drainages and so on, we have needed the optimum designs of suction sumps in order to achieve low initial/running costs, compact size, high efficiency and high performance. In the present study, we attempt to reveal the unsteady three-dimensional flow structure in a suction sump with the vertical-wet-pit-pump configuration. Using the 3D-PTV (three-dimensional...
Insufficient understanding of large deviations between theoretical efficiency and measured efficiency is a major problem encountered in the water-jet propulsion design and application. Therefore, reason analysis of the poor efficiency is necessary. In this paper, CFD was directly adopted in the hydraulic loss distribution of water-jet propulsion. At reliable conditions, nearly 50% hydraulic losses...
In order to explore the mechanism of local pipe for affecting pump performance, from the point of flow pattern, the flow pattern, water flux and lifting efficiency are tested by changing air flow rate and submergence ratio. The test results clearly show that the style of pipe in the air-lift can hardly affect the flow pattern, but it has great effect on the pump performance. The water flux and efficiency...
The flow in a pump sump is a very complicated one, which has three dimensional flow patterns, deformed free surface, and many unsteady vortices. As the model testing has a problem of similarity, CFD simulation method attracts attention in these days. In this study, a model case flow in the pump sump with simplified shape is simulated numerically. The flow is simulated as three-dimensional with free...
In modern turbomachinery, accurate prediction of rotor blade shape for manufacture from its design shape is vital for performance, efficiency and aeroelastic stability. The manufacture “cold” blade shapes of a large-scale ratio transonic hollow fan and a NASA Rotor 67 fan were predicted from the design “hot” shapes utilised four kinds of numerical simulation methods, such as non-coupling, weak coupling,...
The microfabrication technology of MEMS has been successfully applied in the field of micropropulsion for micro/nano satellites. Among various types of MEMS micro thrusters developed so far, vaporizing liquid microthruster (VLM) has been widely explored for its ability to produce continuously variable thrust in the micro-Newton (μN) to milli-Newton (mN) range. VLM is a micromachined chamber which...
Propellant refillable reservoir (PRR) is one of the most important parts of the vane-type surface tension tank (STT), and its fluid storage and management performance will determine propellant management ability of STT under microgravity environment. In present paper, numerical analysis and microgravity experiment study on fluid storage performance and transfers behaviour of a new type PRR are carrying...
In order to study the performance of jet flushing, many indoor and field experiments were conducted by using a self-developed self-excited inspiratory (or non-aspirating) pulsed jet nozzle-deep water simulation test system and shipborne flushing system. The results indicated that self-excited inspiratory pulsed liquid-gas jet nozzle is better than self-excited pulsed jet nozzle in starting sediment...
The structural characteristics of one kind of the stress mode vortex flow meters was introduced for raising up its survey performance. According to elaborately expounding the vortex survey theory, the mathematical relation between the variations of vortex force and stress was studied. The mathematical model of vortex flow survey was established and simulated and the simulated results were carefully...
Transient flow characteristics in piezoelectric micropumps with flat diffuser/nozzle tubes were studied by numerical simulation. There is phase difference between velocity and pressure at high frequency. The effect of Reynold number, diffuser angle and excitation frequency on phase difference was studied. Pressure loss coefficient and tube efficiency were discussed as Womersley number ranging from...
ADCP (Acoustic Doppler Current Profiler) is a kind of acoustic instruments which works according to the Principle of Doppler effect. Now, ADCP is widely used in the measurement of current velocity and flow of rivers and oceans.
Under the condition of different choke pipe diameters, the choking-cavitator was made numerical analysis by Fluent software and the cavitation noise signals were tested. The effect of the diameters on the cavitation characteristics of chocking-cavitator was investigated. It is shown that as the choke pipe diameters increases, the maximum pressure gradient increases and the choking section moves to...
In order to further study the principle of the wave energy generating set, 3D full channel numerical calculations were carried out of the Wells turbine used for the secondary energy conversion of the wave energy generating unit. The main investigated items included the relations among turbine performance and stagger angles, as well as different blade profiles in forward and reversed flow field respectively...
In order to further reveal the cavitation performance of high speed centrifugal pump with fairly low inlet pressure, the physical model of the high-speed centrifugal pump which contains the cylindrical inlet flow channel, the variable-pitch inducer, the impeller and the outlet volute is set up. Here a set of jet device that injects a small part of the working fluid with higher energy from somewhere...
Residual heat removal pump (RHRP) is one of key equipments in 1000 MW nuclear power plants; its faction is to transport high temperature and pressure medium. Vibration and dynamic stress which is caused by the interaction between the fluid and structure can affect the reliability of RHRP. This paper presents an investigation of internal flow field of residual heat removal pumps, by using a combined...
By-pass actuators are both indispensable and critical components for thrust vector control of supersonic vehicles. Detailed flow features concerned with by-pass flow play the key role in thrust vectoring system. A computational fluid dynamics (CFD)-based study was conducted in supersonic nozzle with by-pass flow passage. To validate the numerical model, a comparison with experimental results was performed...
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