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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...
This paper presents a procedure for design optimization of a Multiphase pump used for offshore plants. The Multiphase pump consists of a Helico-Axial type impeller with three blades and diffuser with eleven vanes. Variables and ranges defining blade angles of impeller and diffuser were selected as design variables for influences evaluation by using 2K factorial method. Based on the selected variables,...
Turbine shaft is one of key parts of turbocharger. Nowadays, the most common way to produce turbine shaft is to connect nickel-based high-temperature alloy K418 turbine and 42CrMo steel shaft by friction welding. Because the density of TiAl alloy is less than half of nickel-based high-temperature alloy K418, the weight of turbine made from TiAl can be reduced more than half. Therefore, the transient...
In this paper, design optimization for mixed-flow pump impellers has been studied using a commercial computational fluid dynamics (CFD) code and design-of-experiments (DOE). The design variables of meridional plane and vane plane development were defined for impeller design. The blade shape of impeller was designed using traditional method that the inlet and exit angles are connected smoothly. First,...
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...
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...
With the development of the nuclear power, the performance of the pump, which is used in the nuclear power plant, is becoming more and more important. The condensate pump cavitation becomes the prime performance. The impeller of the first stage must have sufficient cavitation resistance. Jointed with Tsinghua University, KSB Shanghai Company designed and developed a new impeller with good cavitation...
To optimize the structure of water lubricated bearings, six kinds of bearings in different eccentricity ratio (ε) have been designed. The models are built by CREO and numerically simulated by CFX. Fluid-solid coupling is used to compare the relationship between the pressure and the load carrying capacity with different eccentricity ratio (ε) by ANSYS workbench. The analysis results show that the load...
The purpose of this paper is to compare the spurting characteristic of the self-excited inspiration pulsed jet nozzle (SEIPJN) which was proposed by the author with self-excited pulsed jet nozzle (SEPJN) under submerged conditions. Based on a detailed experimental measurement for the impact pressure of two nozzles under different working pressure and confining pressure, the erosion mechanism of low-pressure...
The ship gas turbine exhaust ejector is the central component parts, which can reduce or even eliminate the infrared radiation signal of ship gas turbine exhaust systems. In the design of exhaust ejector, structure forms of nozzle have a significant influence on its ejector effect. A rational nozzle, which is made to work in a narrow space and reduce the exhaust temperature effectively while minimizing...
A connecting groove is added to the minimum flow valve with labyrinth channel as the optimized structure for flow field, and the internal flow characteristics of the valve are simulated by CFD method in a specific working condition. The result indicates that with the same pressure drop between the import and export, cavitation appears in the minimum flow valve under the specific working condition...
Based on a perforated sleeve valve, three new structural types are designed and studied numerically. The commercial software FLUENT is used to simulate the flow characteristics and predict the flow fields under different valve openings. The discharge capacities of the four valves are calculated and compared. Results show that different kinds of inherent characteristic and discharge capacity can be...
In this paper, the cavitation characteristic of a hot water pump was numerically calculated based on mixture model. The critical net positive suction head (NPSHc) was obtained. The vapor volume fractions were obtained in different NPSH by changing the inlet pressure. Changing the temperature of the fluid, NPSHc of the pump were obtained. The results showed that when NPSH decreased, the vapor fraction...
Renewable energy sources which are gaining popularity over conventional resources mostly produce intermittent power as they fall under the influence of natural phenomena as daily cycle or weather conditions. However, worldwide remarkable growth of electricity generation from renewable resources in the recent years has resulted in the decentralized production posing network load stability problems,...
The application of water jet in removing ice from river, sea or surface of objects has many advantages, such as no mechanical strike and damage, easy control and portability. While very few investigations have been carried out. So, experimental study of deicing by means of water jet is conducted in this paper. In the experiment, the ice is naturally frozen in a rectangular mold. And the ice is struck...
The mechanism of hydraulic cavitation is far from known for the complexity of itself. The core of the technology of hydraulic cavitation is cavitation nozzle. Researches show that cavitation phenomenon displays some chaotic properties. On this basis, the cavitation noise signals,which are produced by the common cavitation nozzles in different shapes,are collected by hydrophone experimentally. The...
The water hammer occurs frequently in the water conveyance system, especially in the long distance system. In order to prevent the occurrence of vaporization phenomenon in the pipelines caused by the power-off water hammer, installation of air valve is the most common water hammer protection measure. The air valve should not only discharge the air of the tube when the station start the pump, but also...
The measurement of flow rate is the most difficult and challenging part of the hydropower station tests. This paper provided a method based on differential pressure which has high precision, less cost and convenience. Three-dimensional numerical simulation was performed for NTNU (Norwegian University of Science and Technology) model turbine in steady conditions, meanwhile a new expression of flow...
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