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Analysis on Energy Conversion of Screw Centrifugal Pump in Impeller Domain Based on Profile Lines  [PDF]
Hui Quan,Rennian Li,Qingmiao Su,Wei Han,Pengcheng Wang
Advances in Mechanical Engineering , 2013, DOI: 10.1155/2013/512523
Abstract: In order to study the power capability of impeller and energy conversion mechanism of screw centrifugal pump, the methods of theoretical analysis and numerical simulation by computational fluid dynamics theory (CFD) were adopted, specifically discussing the conditions of internal flow such as velocity, pressure, and concentration. When the medium is sand-water two-phase flow and dividing the rim of the lines and wheel lines of screw centrifugal pump to segments to analyze energy conversion capabilities which along the impeller profile lines with the dynamic head and hydrostatic head changer, the results show that the energy of fluid of the screw centrifugal pump is provided by helical segment, and the helical segment of the front of the impeller has played the role of multilevel increasing energy; the sand-water two phases move at different speeds because the different force field and the impeller propeller and centrifugal effect. As liquid phase is the primary phase, the energy conversion is mainly up to the change of liquid energy, the solid phase flows under the wrapped action of liquid, and solid energy is carried out through liquid indirectly. 1. Introduction As a new kind of impurity pump, screw centrifugal pump combines the advantages of screw pump and centrifugal pump, and the special structure can bring into play their advantages, sufficiently (Figure 1). Comparing with the traditional impurity pump, screw centrifugal pump has a series of strong advantages, such as without clogging, suction performance, adjustment of the performance, and cavitation resistance, and with no load, high efficiency, and high efficiency zone width [1, 2]. Figure 1: Picture of the impeller. Screw centrifugal pump internal flow apparently shows mixed spiral movement because of the unique structure of impeller, comparing with ordinary centrifugal pumps; there is still much room for efficiency improvement for screw centrifugal pump. Screw centrifugal pump is a typical sand-water two-phase flow pump, due to the different density of the solid and liquid phases, resulting in the slip velocity, which does not only affect the hydraulic performance of the pump, but also makes it easy for the solid particles and over-current surface conflicts caused by the wear of the pump flow parts and other problems [3–5]. Therefore, the study of mechanism of energy conversion and the analysis of factors that impact the conversion have a great significance for the improvement of efficiency. It is also the primary problem that optimizes the design methods of established impurity pump and
PRESSURE AND SWIRL OF LIQUID ON THE OUTLET OF CENTRIFUGAL PUMP IMPELLER  [cached]
Waldemar J?dral
Bulletin of the Institute of Heat Engineering , 1992,
Abstract: Divergences between values of potential head Hp of a centrifugal pump, computed from different literature formulae, are discussed. The new, more accurate, formulae for head Hp and swirl coefficient c'u2 calculation are derived. One dimensional (Euler) theory of hydraulic turbomachines is applied.
Numerical Identification of Key Design Parameters Enhancing the Centrifugal Pump Performance: Impeller, Impeller-Volute, and Impeller-Diffuser  [PDF]
Massinissa Djerroud,Guyh Dituba Ngoma,Walid Ghie
ISRN Mechanical Engineering , 2011, DOI: 10.5402/2011/794341
Abstract: This paper presents the numerical investigation of the effects that the pertinent design parameters, including the blade height, the blade number, the outlet blade angle, the blade width, and the impeller diameter, have on the steady state liquid flow in a three-dimensional centrifugal pump. Three cases were considered for this study: impeller, combined impeller and volute, and combined impeller and diffuser. The continuity and Navier-Stokes equations with the k-ε turbulence model and the standard wall functions were used by means of ANSYS-CFX code. The results achieved reveal that the selected key design parameters have an impact on the centrifugal pump performance describing the pump head, the brake horsepower, and the overall efficiency. To valid the developed approach, the results of numerical simulation were compared with the experimental results considering the case of combined impeller and diffuser. 1. Introduction At the present time, single and multistage centrifugal pumps are widely used in industrial and mining enterprises. One of the most important components of a centrifugal pump [1] is the impeller. The performance characteristics related to the pump comprising the head, the brake horsepower, and the overall efficiency rely a great deal on the impeller. To achieve better performance for a centrifugal pump, design parameters such as the number of blades for the impeller and the diffuser, the impeller blade angle, the blade height for the impeller and the diffuser, the impeller blade width, the impeller diameter, and the volute radius must be accurately determined, due to the complex liquid flow through a centrifugal pump. This liquid flow is three-dimensional and turbulent. It is therefore important to be aware of the liquid flow’s behavior when traveling through an impeller. This can be done by accounting for the volute and/or the diffuser in the planning, design, and optimization phases at conditions of design and off-design. Many experimental and numerical studies have been carried out on the liquid flow through a centrifugal pump [2–21], where the effects of the number of impeller blades on the pump’s performance were examined experimentally in [11, 12]. The effects of the impeller outlet blade angle on the pump’s performance were also investigated numerically [13, 14], using a CFD code and experimentally in [15]. In [16] the dynamic effects due to the impeller-volute interaction within a centrifugal pump were numerically investigated, whereas the effects of the volute on velocity and pressure fields were examined in [17, 18].
Numerical Investigation of a First Stage of a Multistage Centrifugal Pump: Impeller, Diffuser with Return Vanes, and Casing  [PDF]
Nicolas La Roche-Carrier,Guyh Dituba Ngoma,Walid Ghie
ISRN Mechanical Engineering , 2013, DOI: 10.1155/2013/578072
Abstract: This paper deals with the numerical investigation of a liquid flow in a first stage of a multistage centrifugal pump consisting of an impeller, diffuser with return vanes, and casing. The continuity and Navier-Stokes equations with the turbulence model and standard wall functions were used. To improve the design of the pump's first stage, the impacts of the impeller blade height and diffuser vane height, number of impeller blades, diffuser vanes and diffuser return vanes, and wall roughness height on the performances of the first stage of a multistage centrifugal pump were analyzed. The results achieved reveal that the selected parameters affect the pump head, brake horsepower, and efficiency in a strong yet different manner. To validate the model developed, the results of the numerical simulations were compared with the experimental results from the pump manufacturer. 1. Introduction Nowadays, multistage centrifugal pumps are widely used in industrial and mining enterprises. One of the most important components of a multistage centrifugal pump is the impeller (Peng [1]). The performance characteristics related to the pump including the head, brake horsepower, and efficiency rely heavily on the impeller. For a more performing multistage pump, its design parameters, such as the number of stages, impeller blades, diffuser vanes and diffuser return vanes, angle of the impeller blade, height of the impeller blade and diffuser vane, the width of the impeller blade and diffuser vane, the impeller and diffuser diameter, the rotating speed of the impeller, and the casing geometry must be determined accurately. Moreover, a stage of a multistage centrifugal pump is composed of an impeller, diffuser, and casing. Given the three-dimensional and turbulent liquid flow in a multistage centrifugal pump, it is very important to be aware of the liquid flow’s behavior when flowing through a pump stage accounting for the wall roughness. This can be achieved by taking all stage components into consideration in the planning, design, and optimization phases in design and off-design conditions. Many experimental and numerical studies have been conducted on the liquid flow through a single centrifugal pump (Cheah et al. [2], Ozturk et al. [3], Li [4], Liu et al. [5], González et al. [6], Asuaje et al. [7], and Kaupert and Staubli [8]) and a multistage centrifugal pump (Huang et al. [9], Miyano et al. [10], Kawashima et al. [11], and Gantar et al. [12]), where Cheah et al. [2] had numerically investigated the complex pump internal flow field in a centrifugal pump in design and
Pressure Fluctuation in a Vaned Diffuser Downstream from a Centrifugal Pump Impeller  [PDF]
Akinori Furukawa,Hisasada Takahara,Takahiro Nakagawa,Yusuke Ono
International Journal of Rotating Machinery , 2003, DOI: 10.1155/s1023621x03000265
Abstract: Periodic flows downstream from a centrifugal pump impeller in vaneless and vaned diffusers were measured by using a single hole yawmeter and a phase-locked sampling method. The flows were also calculated by an inviscid flow analysis using the blade-surface singularity method. The periodic variations in calculated static pressure with the impeller rotating quantitatively agree well with the measured ones. The flow behaviors in the vaned diffuser are discussed, citing measured and calculated results. The potential interaction between the impeller and the diffuser blades appears more strongly than the impeller-wake interaction. The appearance of static pressure fluctuations due to the impeller's rotating in the fully vaned zone is different from that in the semivaned zone of the diffuser. The existence of the peripheral blade surface of the impeller outlet with an outlet edge of the pressure surface causes violent pressure fluctuations in the vaned diffuser.
Simulink/MATLAB Model for Assessing the Use of a Centrifugal Pump as a Hydraulic Turbine  [PDF]
Peter E. Jenkins, Artem Kuryachy
World Journal of Mechanics (WJM) , 2018, DOI: 10.4236/wjm.2018.87021
Abstract: A centrifugal pump used as a hydraulic turbine in producing power for a microhydropower system is multifaceted. Centrifugal pumps are far more ubiquitous than turbines in the turbomachinery market, therefore being more readily available to the consumer. Additionally, they are cheaper. Hydraulic turbines undergo rigorous CFD simulation design and testing to establish their blade geometries and ranges of operation. This results in a refined but very expensive final product. Centrifugal pumps are thus presented as a logical alternative seeing that they can physically perform the same task as a hydropower turbine albeit at a reduced efficiency. This paper presents the results of an analysis and simulation to assess the use of a centrifugal pump as a hydraulic turbine.
Three-dimensional simulation of the entrance-impeller interaction of a hydraulic disc pump
Pérez,José Leonardo; Carrillo,Luis Pati?o; Espinoza,Henry;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2006,
Abstract: a study of the fluidynamic behavior of the entrance-impeller interaction of a hydraulic disc pump is presented, through numerical simulations, using the finite volume method. a three-dimensional numerical model was developed, using the technique of multiblocks and structured meshes, by means of the commercial code cfx 4.3tm. the simulated model corresponds the flat impeller of (203 mm) of diameter to the exit, of a disc pump of simple suction. 8 flows were simulated, in those that the nominal flow, the maximum flow and the minimum flow were included. the simulations were carried out in stationary state and it took advantage the periodic condition of the flow inside the impeller, being reduced to section ?. the obtained load-flow curve was compared with the experimental pump curve given by the maker. the obtained curve, through the numerical results of the simulations, possesses a similar behavior to the experimental one, with values of load superiors to 15%, for the near flows to the nominal one. additionally, the interaction entrance-impeller was analyzed through of pressure and velocities profiles, that which allowed to know and to understand the behavior of these variables for the simulated conditions.
The influence of the inlet angle over the radial impeller geometry design approach with ANSYS
Sanda Budea,Daniela Carbune Varzaru
Journal of Engineering Studies and Research , 2012,
Abstract: This paper presents in brief an own application (numerical code) for quick design of the turbo machines impellers. Based on this numerical method, this paper analyses the influence of the blades' angles on the radial impeller geometry from the centrifugal pumps: the influence of the inlet and outlet angles of the blades over the hydraulic channel size, over the number of the blades and over the blades' angular extension. In centrifugal pumps design, a special attention must be given of the impeller inlet and outlet angles. These influences include also the pump efficiency, for 1-2 percent. The impeller design methods starting from the pump flow, the head, the rotation speed and ranging blades inlet and outlet angles, gives completely the impeller geometry -the suction and discharge diameters of the impeller, the number of blades and the size and shape of the hydraulic channel and estimates the efficiency for centrifugal pumps. Once the impeller geometry established, the dates were imported in ANSYS code, for graphical design and 3D visualization of the radial impeller, also for the streamlines flowing visualization.
Effects of Flow Rate and Viscosity on Slip Factor of Centrifugal Pump Handling Viscous Oils  [PDF]
Wen-Guang Li
International Journal of Rotating Machinery , 2013, DOI: 10.1155/2013/317473
Abstract: Slip factor is an important parameter in the hydraulic design of centrifugal pump impeller for handling viscous oils. How to extract the factor from CFD computational results and how flow rate and liquid viscosity to affect it remain unclear. In the present paper, the flip factor was estimated by means of two approaches: one is from the velocity triangles at the impeller outlet and the other is due to the impeller theoretical head of 3D turbulent viscous fluid. The velocity of water and viscous oils in the impeller and volute computed by CFD was validated with LDV measurements at the best efficiency point. The effect of exit blade angle on slip factor was clarified. It was shown that the two approaches result into two different slip factors. The factors are significantly dependent of flow rate; however, the liquid viscosity seems to take less effect on them. Volute is responsible for reduction in tangential velocity of liquid at the outlet of impeller at low flow rates. The slip factor of impeller with large exit blade angle is not sensitive to flow rate. 1. Introduction The performance of centrifugal pump handling water and viscous oils was investigated numerically by using a CFD code FLUENT based on a steady, 3D, and incompressible turbulent flow. The turbulence effect was involved with the standard turbulence model and wall roughness was taken into account with the nonequilibrium wall function in [1]. The effect of liquid viscosity on pump performance was clarified through observing the pump head and hydraulic efficiency as well as hydraulic loss coefficient in terms of flow rate. A comparison of computed and experimental overall performance of the pump was made. It was confirmed that the “sudden-rising head effect” exists and is caused from the high viscosity and certain large surface roughness. The volute results in an increasing influence on the flow around the impeller exit at a low flow rate. Slip factor is one important design parameter for deciding a correct impeller diameter of centrifugal pump. The factor can be obtained theoretically and experimentally. The typical investigations include those conducted by Kasai [2, 3], Sakai and Watanabe [4], Noorbakhsh [5], Whitfield [6], Murata et al. [7], Harada and Senoo [8], Visser et al. [9], von Backstron [10], Hassenpflug [11], Ji et al. [12], Qiu et al. [13], and so on. The slip factor depends on impeller geometry [5, 7, 9, 10, 14], flow rate [2–4, 6, 13, 15], and viscosity of the liquid pumped [16, 17]. Recently, Slip factor is increasingly estimated by using CFD approach [18–22]. Thus it is
Experimental Investigation of the Effect of Radial Gap and Impeller Blade Exit on Flow-Induced Vibration at the Blade-Passing Frequency in a Centrifugal Pump  [PDF]
A. Al-Qutub,A. Khalifa,Y. Khulief
International Journal of Rotating Machinery , 2009, DOI: 10.1155/2009/704845
Abstract: It has been recognized that the pressure pulsation excited by rotor-stator interaction in large pumps is strongly influenced by the radial gap between impeller and volute diffusers/tongues and the geometry of impeller blade at exit. This fluid-structure interaction phenomenon, as manifested by the pressure pulsation, is the main cause of flow-induced vibrations at the blade-passing frequency. In the present investigation, the effects of the radial gap and flow rate on pressure fluctuations, vibration, and pump performance are investigated experimentally for two different impeller designs. One impeller has a V-shaped cut at the blade's exit, while the second has a straight exit (without the V-cut). The experimental findings showed that the high vibrations at the blade-passing frequency are primarily raised by high pressure pulsation due to improper gap design. The existence of V-cut at blades exit produces lower pressure fluctuations inside the pump while maintaining nearly the same performance. The selection of proper radial gap for a given impeller-volute combination results in an appreciable reduction in vibration levels. 1. Introduction This investigation is focused on the study of the radial gap and blade exit design in centrifugal pumps. The investigation was motivated by the need to trace the root-cause of high-level vibrations at the blade-passing frequency (BPF) and its higher harmonics, which existed in the boiler-feed pumps (BFPs) in a major power plant. The boiler feed pumps have a V-cut at impeller blades’ exit. The problem caused cracking of the connecting piping welds and the gage attachments, which required frequent replacements of such components. The pump manufacturer attempted several remedial actions; however the problem persisted. A thorough study of the vibration records obtained through various field measurements at the pump casing and bearing housing as well as trending records has led to the elimination of other possible mechanical/structural sources of vibrations and pointed out to the flow-induced nature of the problem. Accordingly, the investigation was focused on the pump design, as related to the impeller-diffuser interaction and the effect of the radial gap. The impeller/volute radial gap is an important design and performance parameter in fluid handling machines, for example, pumps, compressors, and turbines. The proper selection of such a gap is often a best compromise between efficiency and reliability. In high-energy pumps, the minimum radial gap is a critical design consideration that controls the pressure pulsation
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