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Sha Y.,Zhejiang University of Science and Technology | Liu X.,Harbin Electrical Power Equipment Co
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

In order to study the characteristics of the flow field and gas-liquid two-phase flow hydrotransport in vortex pumps, the performance test and the measurement of flow field in volute at optimal operating condition with five-hole probes were conducted on a self-built vortex pump (32WB8-12). Based on these experiments, the qv-H, qv-P, qv-η, qv-NPSHc performance curves and the absolute velocity v, circumferential velocity vu, radial velocity vr, axial velocity vz, and the flow static pressure ps, on the 5 measuring points were obtained. The obtained parabolic qv-NPSH performance curve shows the opposite tendency compared to the centrifugal pump. The mechanical properties of the four kinds of forces in gas-liquid two-phase flow were analyzed with the Navier-Stokes Equation, and the results indicated the constraint relationship between performance and mechanical factors. Furthermore, the principle of gas-liquid flow hydrotransport and the difference between cavitating current and gas-liquid flow were also presented. The interior flow field in the pump under the optimal condition has been numerically simulated by FLUENT software based on the renormalization group k-ε turbulence model (RNG k-ε model) through which the pressure and velocity as well as gasvolume distribution of three cross sections in the vortex pump were obtained. The experimental results also showed that axial vortex was the dominant flow in the pump inlet, and the airflow gathered in the volute inlet with low pressure. The difference of molecule size, shape, and elastic modulus between airflow and liquid leads to the variations of the inertia, friction, and buoyancy forces in flow field, which explains the relationship between performance and parameters of the internal flow and gas-liquid suction as well as the head formation principle of vortex pump. The numerical results are in good agreement with flow field measurement data. The results show that the internal flow in the vortex pump mainly consists of through flow. The flow in the impeller region is of forced vortex characters, and the flow in volute is similar to the combined vortex with backflow, which is a non-axisymmetric unsteady flow with quite high turbulence intensity. All these should be main reasons for the relatively low efficiency of the vortex pump. The distortional principle of velocity field and the channel streamline with two-phase flow inside the vortex pump have been investigated in this article. This research provides a model of gas-liquid two-phase flow and cavitating current in vortex pump. Source


Zhao W.-D.,Harbin Institute of Technology | Liu Y.-X.,Harbin Electrical Power Equipment Co | Du B.-C.,Harbin Institute of Technology | Cui S.-M.,Harbin Institute of Technology
Dianji yu Kongzhi Xuebao/Electric Machines and Control | Year: 2014

Steam blockage faults inside the circular lead of large turbogenerators, which initiated by some installation mistakes, will burn the lead and cause a non-normal shutdown accident. According to specific fault cases, the conjugate heat transfer model of the lead and its cooling water was constructed in this paper, based on the computational fluid dynamics. Thermal field of the lead and its water under a wrong return pipe connection was calculated, and then the relationship between temperature characteristics and the degree of blockage was analyzed. The calculation and analysis results indicated that, the abnormal low flow rate caused by a wrong return pipe connection was the direct reason of steam blockage. The lead began to melt about 30 min after the formation of steam blockage. On this basis, this paper suggests a normative installation and extra thermal and flow monitor devices to prevent faults. Source


Zheng R.G.,Shenyang University | Zhang X.X.,Harbin Electrical Power Equipment Co
Applied Mechanics and Materials | Year: 2013

Sliding wear behavior of the (NbSe2+SiC)/Cu composite was studied on a pin-on-disc wear tester under various electrical currents and applied loads. The worn surfaces were characterized using scanning electron microscopy and energy dispersive spectroscopy to probe the wear mechanisms. Experiment results show that the friction coefficient and wear rate of (NbSe2+SiC)/Cu composite increased with increasing of the normal load. Adhesive wear, abrasive wear and fatigue wear were the main wear mechanism during the sliding process. © (2013) Trans Tech Publications, Switzerland. Source


Sha Y.,Zhejiang University of Science and Technology | Liu X.,Harbin Electrical Power Equipment Co
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

In order to study the solid-liquid two-phase flow hydrotransport characteristics of vortex pump, the energy consumption of pump caused by internal resistance is divided into two parts: the mechanical losses and hydraulic losses, also the calculation of mechanical efficiency ηm and hydraulic efficiency ηf is elaborated. This paper investigates the 32WB8-12 vortex pump's parameter of hydraulic design structure. The crops solid-liquid two-phase flow hydrotransport experiment plan is established, meanwhile the performance experiments of clean water, rapeseed, wheat and soya hydrotransport are conducted on a self-built vortex pump, after taking above experiments that the qv-H, qv-P, qv-η, qv-NPSHc curves are obtained. The experimental results indicates the pump's hydrotransport efficiency of spherical rapeseed is higher than clean water's and the others' two-phase flow. The pump anti-cavitations are reduced with the solid-liquid two-phase flow hydrotransport. The head and hydrotransport efficiency of pump ordinarily decrease with increased particle size under the condition of constant particle concentration. Moreover, the hydraulic efficiency of transporting regular sphere shape particles such as rapeseed is higher than the clean water's, wheat's and soya's. The characteristics are considered based on the slip flow with the principle of relativity that sliding liner and rotary motion between particles and fluid flow. Associated with particle's size and shape, the particles suffered inertial force, friction force and buoyant force have significance on fluid field, all above information also proved that internal two-phase flow of vortex pump meet the principle of distortion velocity. From the experimental data analyses, some explanations are given for the link and changing trends between the external characteristics and internal flow nature. This research can provide a reference for building the model of fluid solid two-phase flow in vortex pump. Source


Lv Y.H.,Harbin Engineering University | Gai D.Y.,Harbin Engineering University | Song Y.Q.,Harbin Electrical Power Equipment Co | Ma X.Q.,Harbin Engineering University
Strength of Materials | Year: 2015

Carburizing and shot peening are commonly accepted surface treatment methods used to improve the surface properties of materials. Researchers are making attempts to optimize their application for obtaining superior mechanical properties. However, there are few comprehensive reports on this problem. The combination of carburizing and shot peening is used for the surface treatment of 17-CrNi6-Mo steel. This is followed by detailed analysis employing optical and scanning electron microscopy, microhardness testing, surface roughness measurements, and the measurement of residual stresses using X-ray diffraction. The results show that shot peening can further improve the microstructure and surface properties of carburized specimens since it induced the phase transformation of a carburized layer. Moreover, simulation of the phase composition variation curve along with the change in the carbon content and the continuous cooling transformation (CCT) curve of the specimen is also presented. The results are used to elucidate the carburizing effect on a 17-CrNi6-Mo steel surface microstructure. © 2015 Springer Science+Business Media New York Source

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