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Zhang Y.-L.,Zhejiang University | Zhu Z.-C.,Zhejiang University | Zhu Z.-C.,Zhejiang Sci-Tech University | Cui B.-L.,Zhejiang Sci-Tech University | And 2 more authors.
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2012

To overcome the difficulty in implement of boundary conditions in the numerical simulation of transient flow in a centrifugal pump during stopping period, a closed-loop pipe system including the pump was built to accomplish a self-coupling computation. The results show that the decreasing course of flow rate lags behind that of rotational speed, and the head decreases more quickly. The continuous variations of flow angle or angle of attack are the root reason for the evolution of flow field in the pump during stopping period. The rotor-stator interaction makes flow rate present a slight fluctuation feature, in other words, the flow rate isn't invariable in a steady operating condition. During stopping period a considerably transient effect has been demonstrated, such an effect cannot be predicted precisely by means of a flow model based on the quasi-steady assumption so far. In conclusion, the transient characteristic of the centrifugal pump has preliminarily been revealed by using the CFD technique during stopping period, and the present method has provided a valuable reference for investigating into the transient behavior of other turbomachinery. Source

Lin Z.,Zhejiang Sci-Tech University | Lin Z.,The Zhejiang Provincial Key Laboratory of Fluid Transmission Technology | Lin Z.,Zhejiang Institute of Mechanical and Electrical Engineering Co. | Ma G.,Zhejiang Sci-Tech University | And 8 more authors.
Journal of Natural Gas Science and Engineering | Year: 2016

This article is intended to elaborate different inlet velocities that respectively are 13 m/s,15 m/s and 17 m/s to influence flow resistance characteristics and the internal flow characteristics of gate valve in the medium-low pressure gas transmission. This paper presents the CFD analysis of flow resistance characteristics and the internal flow characteristics of gate valve in a gate valve with different inlet velocity. Gate valves under different inlet velocity have eight relative opening degrees that respectively are 1/8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8 and 1. For every relative opening degree of gate valve structure, the systematic CFD simulations of flow resistance, pressure fluid, velocity fluid, velocity streamline and pressure coefficient characteristics. The study mainly analyses the pressure field distribution, velocity distribution, the velocity streamline distribution when the relative opening degree is 1/8, 2/8 and 1. Experimental measurements are also conducted for flow resistance characteristics and then compared with simulated flow resistance results. The CFD simulated flow resistance results show a good agreement with that of experimental flow resistance based on the Reynolds Stress Model (RSM) turbulence model provided by fluent software. Through analysis of flow resistance properties and internal flow characteristics, we concluded that it is not stable before the relative opening degree 2/8 that the valve flow resistance characteristics and internal flow characteristics, which need to be optimized; however, the valve flow resistance characteristics and flow characteristics gradually can be gradually stabilized after the relative opening degree 2/8, and does not have the characteristics of regulating valve. In the process of gas transmission, pressure energy loss mainly occurs in the valve core. © 2016 Elsevier B.V. Source

Wu X.Y.,Zhejiang Institute of Mechanical and Electrical Engineering Co.
Advanced Materials Research | Year: 2014

In this paper, finite element model (FEM) of a reinforced concrete structure cantilevered slab was established in non-linear finite element software ABAQUS. Influence of cantilever length and tensile reinforcement on the structural displacement and vibration frequency was calculated. The results show that the vibration frequency of the first order and maximum displacement will various with the diameter of the reinforced cantilever slab and the length of the cantilevered slab. This paper will offer the references to the analysis and design of the cantilever slab. © (2014) Trans Tech Publications, Switzerland. Source

Wu X.,Zhejiang Institute of Mechanical and Electrical Engineering Co.
Applied Mechanics and Materials | Year: 2012

The deployable structure of the ring truss have advantage properties, which can be used as an effective supporting structure of deployable antenna. The deployable experiment of ring truss antenna showed that there was asynchronous phenomenon at the course of the deployment. Dynamics theory including constraint equations and considering friction factor are built firstly. Then simulation is studied systematically for the deployment process of ring truss deployable antenna. At last, the conclusions are obtained that the friction insulted in tensile forces of the cable drive decrease and the asynchronous phenomenon in the process of the deployment. It will give some help to the design and manufacture of the ring truss antenna. © (2012) Trans Tech Publications, Switzerland. Source

Li Y.,Zhejiang Sci-Tech University | Zhu Z.,Zhejiang Sci-Tech University | He Z.,Zhejiang Institute of Mechanical and Electrical Engineering Co. | He W.,Hangzhou Dalu Industry Co.
Journal of Thermal Science | Year: 2011

Based on the solid-liquid two-phase mixture transportation test, the renormalization group (RNG) k-e turbulent model was utilized to simulate the solid-liquid two-phase turbulent flow in a centrifugal pump. By comparing the simulated and experimental results, inner flow features were revealed to improve the abrasion characteristic of the solid-liquid two-phase centrifugal pump. The influence of the solid phase on centrifugal pump abrasive performance is small when the particle volume fraction is less than 2.5%. The aggregation degree of the solid particles is enhanced as the particle diameter increases from 0.1 to 1 mm; however, the mixture density on the pressure side is reduced when the particle diameter increases to 1 mm for the impact of inertia. The wear on the hub is most severe for the shear stress on this position; it is also the largest. The wear characteristic is affected greatly by the parameters of the solid phase. The wear chracteristic can be optimized by decreasing the blade outlet angle. In the modified design, the blade angle is different, whereas the other geometric dimensions remain the same. The improved pump is simulated to contrast with the original pump. The results show that the values of mixture density and shear stress both decrease. The wear condition of the blade is improved to a certain extent. © 2011 Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg. Source

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