Papers by Keyword: Hydraulic Performance

Abstract: Thus far, axial flow pumps remain a significant hydrodynamic unit. These pumps have common applications for various systems that require a high flow rate and a lower head. They tend to be less efficient and consume excessive power when operating at low flow conditions. Most of the studies focus on improving the hydraulic performance of these pumps based on the best efficiency point (BEP) flow conditions. This approach is mostly based on the assumption that the pump will always operate at BEP. However, this is not always the case, because the operational condition of the pump may require an adjustment to meet certain system demands. Hence, it is necessary to emphasize the need to improve the hydraulic performance of these pumps for multiple flow conditions. This means that in addition to BEP, the lowest, and the highest operational conditions need to be considered when improving the pump performance. Also, it is important to review the phenomenon of cavitation in every design optimization investigation, given its significance to pump performance and some misrepresentation which are sometimes associated with its assessment. Therefore. the main contribution of this article is to briefly discuss the successful and unsuccessful design optimization methods of an axial flow pump. Furthermore, it highlights the significance of improving the pump performance at multiple flow conditions and also to incorporate the analysis of using CFD methods to analyze the results of cavitation performance in every pump performance improvement investigation.

Abstract: By using the FINE software developed by NUMECA Company, the hydraulic performance of the impeller of a centrifugal pump with spatial guide vanes was numerically simulated. The S-A turbulent model was used to numerically calculate the three-dimensional flow field in the centrifugal pump under three different conditions. The flow analysis shows that the pressure gradient on the vane surface gradually reduces with the increasing of the flow rate; the position of axial vortex between vanes has nothing to do with the flow rate; the tangential flow gradient in the flow passage decreases with the increasing of the flow rate. Compared with the test results, it is obvious that this numerical simulation can accurately predicate the complicated three-dimensional flow and the hydraulic performance of the pump.

Abstract: This paper introduces a minor drainage pump used in air-conditioning system. The numerical simulation has been done to analyze the internal flow field and sound pressure level in drainage pump. FlUENT is used in this paper. And LES (Large Eddy Simulation) is taken to catch the pressure fluctuation in this flow passage. CFD results show that pressure fluctuation is the main sound source in the pump.

Abstract: This paper, using 3-D numerical simulation and the hydraulic model tests, presents an analysis on hydraulic performance of pumped storage plant inlet/outlet. It discusses the uneven flow coefficient, coefficient of orifice flow distribution and head loss coefficient of inlet/outlet in different sizes. The optimized size has a uniform flow distribution, with less to produce unwanted eddies.

Abstract: Flow path is one of the key components of drip irrigation emitter. Four factors of fractal flow path section area, length, tooth highness and tooth number are interosculated nearly each other, and the influencing process of flow path to hydraulic performance parameters was analyzed with path analysis. The section area and length of the flow path were the main factor affecting on the flow exponent and flow coefficient of drip irrigation emitter, and other ones less. Reducing the section area could debase the emitter flow exponent, and reducing section area and increasing the length of fractal flow path could debase the flow coefficient.

Abstract: Based on CFD numerical simulation, the effect of blade thickness on hydraulic performance was studied in DQ100-64-22 stamping and welding centrifugal pump. Six types of impellers with different blade thickness were assembled in the same pump to be investigated under design condition. The result indicates that both of head and efficiency are getting lower with the increase of blade thickness. Particularly, the downward trend is more striking when the blade thickness surpasses 2mm, but pump head decreases more gently than efficiency as the blade thickness increasing within 2mm.

Abstract: Based on CFD simulations and experimental research, this paper studied the mach of impeller outlet and diffuser inlet in stamping and welding centrifugal pump. The influence of area ratio Y of impeller outlet to diffuser inlet on pump internal flow characteristics and performance was studied. Five different area ratio pump models were analyzed. The results indicate that as the area ratio Y= F3/F2 increase, the velocity of fluid in diffuser inlet decreases continuously, the average static pressure of diffuser outlet increases, and the head and efficiency of the pump are risen. When the area ratio increases from Y=1.48 to Y=3.49, the head increases about 3.0% and the efficiency about 2.0%.

Abstract: In the rapid development process of cylindrical drip emitter, the traditional CFD analyzing method was generally carried out based on the planar model of the cylindrical labyrinth channel. However, the result obtained by this method was obviously different with the experimental data. In this paper the cylindrical prototype of the labyrinth channel was proposed and the CFD analysis was carried out based on the hexahedral mesh of the cylindrical labyrinth channel to solve this problem. Then the flow rate and the anti-clogging performance of the emitter were predicted based on the stereo prototype of the labyrinth channel. Consequently, the simulation results were verified and the cylindrical drip emitter was finalized according to its hydraulic performance experiment.

Abstract: Centrifugal pumps adopt annular casings instead of volute casings when working in high temperature and high pressure conditions, which results in conservative safety factors in sacrifice of hydraulic efficiency. This paper presents numerical simulations on two assembly modification methods for one annular casing imitating the volute casing to improve hydraulic performance. Method one was the eccentric axis method. Method two was the extended vane method. Numerical simulation results, given by CFX, showed that both the two method could increase the hydraulic efficiency and head while rise in radial force was small.

Abstract: The software CFDesign was used for the analysis of flow field simulation of two different kinds of drilling bit. The results showed that, if the waterway design of drilling bit was unreasonable, it could result in the following phenomenon: the local position of drilling bit could get severe erode of drilling fluid; the return of flow and eddy currents could be observed in the bottom of drilling well; negative pressure could be detected and might result in cavitation corrosion; the direction vector of flow field were diffused and resulted in cross flow. The waterway structure of arc-bottom bit was more reasonable comparing that of flat-bottom bit.