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Pendulum wave energy converter is one of the important forms of wave power generation. Energy extracting device is the core of converter. Resonance effect can be used to realize efficient energy extracting. To achieve resonance, a transmission scheme is needed to change the stiffness which would influence the natural frequency directly of the energy extracting device. The special working environment...
To further study the characteristics of spiral groove upstream pumping mechanical face seal, a fluid-structure interaction CFD model is developed by the software ANSYS Workbench. The model can be used to predict the pressure distribution and pressure distortion of the seal pair. Compared to the single simulation of fluid film, and to one-way fluid-solid coupling, the results of two-way fluid-solid...
The performance and stability of a high-speed centrifugal pump are closely related to its internal vortex flow. It's significant to study the vortex behaviours in a centrifugal pump, such as its coverage, distribution, physical properties, formation mechanism and energy loss, etc. To analyse these problems, the steady numerical simulations of a high-speed centrifugal pump were conducted using the...
To get more accurate flow in the constant-head pump at starting period, a test model was created. The LES model was used to simulate the inner flow at the starting period. The external characters and their time derivatives were obtained. The blade loading on the middle streamline were analyzed. Normalized helicity was used to analyze vortexes in impeller and vortex core was extracted by the normalized...
This paper numerically investigated the influences of tip clearance of impeller in the 15,000 HP centrifugal compressors. The leakage flow by tip clearance of impeller could be resulted in increasing pressure loss and decreasing performance and efficiency of centrifugal compressor. The numerical simulation using ANSYS CFX was conducted with various values of tip clearance of impeller between 0.6 mm...
Semispherical casing was adopted in a boiler circulating pump considering the operating safety. In order to improve the hydraulic performance and reduce the manufacture cost of the pump casing, a modification attempt on pump casing has been made by adopting a volute shape. By using both steady and unsteady numerical simulations with SST k-ω turbulence model, the hydraulic performances of pumps with...
This paper is to analyze the effects of several factors, including deviation functions, span ratios and numbers of lobes, on the area utilization efficiencies of rotor pumps based on the deviation function method. Four deviation functions are included, including two new deviation functions transformed from the previously proposed functions. Firstly, the applicable ranges of span ratios corresponding...
In order to analyze the instabilities during the hump region, three dimensional unsteady incompressible simulations are carried out using SST k-ω turbulence model for a scaled model pump turbine at the 18 mm guide vanes opening in pump mode. And 12 monitoring points are set on the whole pump turbine model passage. Then, pressure fluctuation for different operation conditions is analyzed compared with...
RFD (Reverse flow divert) set is a kind of maintenance-free delivery system driving by compress-air. It intermittently discharges through its delivery pipe. Without moving part, the optimized design of RFD set is a critical technical for efficient and stable operation. The deficiencies of traditional enumeration algorithms and marginal utility method have been indicated. Then, as the main point of...
In AP1000 reactor system, two canned motor pumps are directly attached to the cold side of the steam generator. In order to investigate the effect of the velocity distortion generated by the steam generator on the performance of the two pumps, CFD method is used to simulate the model pump with three different suction flows, one comes from the straight pipe and the other two come from the cold side...
The head of the centrifugal pump at the zero-charge and low-charge conditions has direct influence on the pump startup. In this paper, a large-size single-suction and single-stage vertical centrifugal pump with medium-low specific speed, which used in the Ganhe pump-station of water transferring project from Niulan River to Dianchi Lake, was taken as the research target. The optimization on the basic...
We conduct subsonic wind-tunnel experiments, in order to investigate the basic aerodynamic characteristics of an autorotating finite flat plate in uniform mainstream, which has a potential for new windmills and waterwheels with very simple structures in addition to new mixers/diffusers. The present study focuses on both the effects of an aspect ratio AR and a tip-speed ratio Ω* upon the tumbling of...
An air amplifier makes air flow increased by ejecting a small amount of air, which results in the Coanda effect: A tendency of keeping fluids attached to an adjacent surface while the air flow is passing along the wall boundary. In this paper, the flow characteristics of an air amplifier were investigated with various flow and geometrical conditions. In particular, various values of the Coanda nozzle...
A new type of flow straightener designed with two coaxial circular pipes structure has been proposed. Flow straightener is used to improve the range of fire fighting water cannon. To know the influence of structure sizes on the performance of water cannon, four factors and three levels orthogonal test was designed. Simulation are carried out using commercial software ANSYS FLUENT. Standard k - ε turbulence...
Large eddy simulation (LES) combined with Schnerr-Sauer (S-S) cavitation model were employed to study three-dimensional flow structure of submerged jet with high Reynolds number in an axis-symmetric cavity. The Reynolds number of working jet is Re = 2 × 105 and cavitation number is σ = 0.59 in measuring point of experiment. The computational result shows good agreement with experimental results. Compared...
Solid cone spray nozzle is primarily used in chemical reaction equipments; its atomization performance directly affects the reaction efficiency. In order to optimize the structure of solid cone nozzle, an experimental study on 3 different types of spaying nozzle was conducted by using high speed camera and laser particle analyzer, then got the injection pressure, spray angle, droplet size and distribution...
The past half century has seen an unprecedented growth of the world's urban population. Increasing urbanization and concern about sustainability and quality of life issues have produced considerable interest in air quality in urban areas. Urban ventilation implies that rural areas may supply relatively clean air into urban canopies and distribute rural air within them to help air exchange and pollutant...
Huangjinxia hydraulic project is a large-scale and important inter-basin water diversion project in Shanxi province. And the pump station installed capacity and design discharge is the maximum among the pump station under construction or having been built in China or even Asia. Moreover, the water diversion process is very complex, and the water diversion discharge range is very extensive. Based on...
In this paper, the author tried to find out how clearance between impeller and tongue would affect the pressure fluctuation. By changing the diameter of the impeller, six transient simulations of a centrifugal pump were conducted. Data from different monitoring points were recorded and analyzed. The result shows that pressure fluctuation decreases with the increasing of the clearance. But the high-frequency...
The temporal and time-mean characteristics of the secondary flow in a linear turbine cascade are investigated using an in-house time-resolved particle image velocimetry (TR-PIV) system and the analysis technique of power spectrum distribution (PSD). The experiments are carried out in a low-speed water tunnel, which is made of scaled-up GE-E3 high pressure blades to form a linear turbine cascade. The...
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