PIV Measurements and CFD Analysis in an Axial-Flow Pump

In this study, an axial flow pump impeller without guide vanes is experimentally investigated. The impeller used in the experiments consists of four blades. The particle image velocimetry technique and a five-hole probe have been used. Measurements of flow velocities in the outer part of the impeller have been made. PIV measurements have been realized in 12 meridian planes between blade-to-blade for design and off-design operating conditions. The meridian velocity is obtained with phase averaged method and the total circumferential mean velocity is obtained with an arithmetical average over the 12 circumferential data. The calculation is based on the CFX-TASC flow CFD code solving the three-dimensional Reynolds-averaged Navier-Stokes equation with RNG k–ε model of turbulence. The paper focuses on the comparisons of the results. Difference for the flow field between numerical and experimental results is small at large and design flow rate, while big difference occurs at small flow rate. It indicates that the numerical model is not suitable for separation flow.

Download Full-text

Interrelationship Between the Efficiency Characteristics and the Pressure Head Gradients Among Axial Flow Pumps

Volume 2: Design, Construction, and Operation Innovations; Compression and Pump Technology; SCADA, Automation, and Measurement; System Simulation; Geotechnical and Environmental ◽

10.1115/ipc1996-1892 ◽

1996 ◽

Author(s):

Takaharu Tanaka

Keyword(s):

Cross Section ◽

Flow Rate ◽

Axial Flow ◽

Internal Flow ◽

Pressure Head ◽

Design Flow ◽

Discharge Valve ◽

Head Gradient ◽

Axial Flow Pump ◽

Flow Pump

There is a correlation between the efficiency of the pump to the head produced. On the axial flow pump, whose efficiency characteristic is favorable, the pressure head gradient between the impeller inlet and the outlet sections, at an equivalent flow rate, may become larger than that for the less favorable axial flow pump. This fundamental interrelation may be held in the flow passage regardless to the flow rate whichever they are operated at design or off design flow rate. There may be a direct correlation between the efficiency of an axial flow pump and the ratio of the discharge valve cross section divided by the pipeline cross section. The smaller this ratio is the better the pressure head gradient is for the same flow rates. This ratio may be useful to estimate relative grade of heads, pressure head gradients, internal flow conditions, and efficiency characteristics among axial flow pumps.

Download Full-text

Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

Mathematical Problems in Engineering ◽

10.1155/2016/6375314 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Fan Yang ◽

Hao-ru Zhao ◽

Chao Liu

Keyword(s):

Prediction Model ◽

Flow Rate ◽

High Efficiency ◽

Guide Vane ◽

Axial Flow ◽

Hydraulic Performance ◽

Operating Conditions ◽

Ann Model ◽

Axial Flow Pump ◽

Flow Pump

In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.

Download Full-text

Research on the Influence of Tip Clearance of Axial-Flow Pump on Energy Characteristics under Pump and Turbine Conditions

Machines ◽

10.3390/machines10010056 ◽

2022 ◽

Vol 10 (1) ◽

pp. 56

Author(s):

Yanjun Li ◽

Qixu Lin ◽

Fan Meng ◽

Yunhao Zheng ◽

Xiaotian Xu

Keyword(s):

Flow Rate ◽

Dissipation Rate ◽

Great Influence ◽

Axial Flow ◽

Operating Conditions ◽

Tip Clearance ◽

Blade Tip ◽

Axial Flow Pump ◽

Flow Pump ◽

Blade Tip Clearance

In order to study the influence of tip clearance on the performance and energy dissipation of the axial-flow pump and the axial-flow pump as a turbine, and find the location of high dissipation rate, this study took an axial-flow pump model as its research object and designed four tip radial clearance schemes (0, 0.2, 1 and 2 mm). The unsteady calculation simulation of each tip clearance scheme was carried out based on CFD technology. The calculated results were compared with the experimental results, and the simulation results were analyzed using entropy production analysis theory. The results showed that, under both an axial-flow pump and axial-flow pump as turbine operating conditions, increasing the blade tip clearance led to a decrease in hydraulic performance. Compared with the 0 mm clearance, the maximum decreases in pump efficiency, head and shaft power under 2 mm tip clearance were 15.3%, 25.7% and 12.3% under the pump condition, and 12.7%, 18.5% and 28.8% under the turbine condition, respectively. Under the axial-flow pump operating condition, the change in blade tip clearance had a great influence on the total dissipation of the impeller, guide vane and outlet passage, and the maximum variation under the flow rate of 1.0 was 53.9%, 32.1% and 54.2%, respectively. Under the axial-flow pump as a turbine operating condition, the change in blade tip clearance had a great influence on the total dissipation of the impeller and outlet passage, the maximum variation under the flow rate of 1.0 was 22.7% and 17.4%, respectively. Under the design flow rate condition, with the increase in tip clearance, the dissipation rate of the blade surface showed an increasing trend under both the axial-flow pump and axial-flow pump as turbine operating conditions, and areas of high dissipation rate were generated at the rim and clearance.

Download Full-text

Numerical and Experimental Investigation of Tip Leakage Vortex Trajectory in an Axial Flow Pump

Volume 1B, Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Fundamental Issues and Perspectives in Fluid Mechanics ◽

10.1115/fedsm2013-16058 ◽

2013 ◽

Author(s):

Desheng Zhang ◽

Weidong Shi ◽

Suqing Wu ◽

Dazhi Pan ◽

Peipei Shao ◽

...

Keyword(s):

Flow Rate ◽

Axial Flow ◽

Tip Clearance ◽

High Speed Photography ◽

Rate Condition ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Starting Point ◽

Axial Flow Pump ◽

Flow Pump

In this paper, the tip leakage vortex (TLV) structures in an axial flow pump were investigated by numerical and experimental methods. Based on the comparisons of different blade tip clearance size (i.e., 0.5 mm, 1mm and 1.5mm) and different flow rate conditions, TLV trajectories were obtained by Swirling Strength method, and simulated by modified SST k-ω turbulence model with refined high-quality structured grids. A high-speed photography test was carried out to capture the tip leakage vortex cavitation in an axial flow pump with transparent casing. Numerical results were compared with the experimental leakage vortex trajectories, and a good agreement is presented. The detailed trajectories show that the start point of tip leakage vortex appears near the leading edge at small flow rate, and it moves from trailing edge to about 30% chord span at rated flow rate. At the larger flow rate condition, the starting point of TLV shifts to the middle of chord, and the direction of TLV moves parallel to the blade hydrofoil. As the increasing of the tip size, the start point of TLV trajectories moves to the central of chord and the minimum pressure in vortex core is gradually reduced.

Download Full-text

Experimental investigation on the correlation of pressure pulsation and vibration of axial flow pump

Advances in Mechanical Engineering ◽

10.1177/1687814019889473 ◽

2019 ◽

Vol 11 (11) ◽

pp. 168781401988947

Author(s):

Xiaohui Duan ◽

Fangping Tang ◽

Wenyong Duan ◽

Wei Zhou ◽

Lijian Shi

Keyword(s):

Pressure Pulsation ◽

Axial Flow ◽

Domain Analysis ◽

Vertical Vibration ◽

High Flow ◽

Design Flow ◽

Flow Rates ◽

Horizontal Vibration ◽

Axial Flow Pump ◽

Flow Pump

Pressure and vibration displacement value are relatively measured by 14 pressure sensors and 2 vibration sensors distributing inside the tank-type model axial flow pump device under different flow rates. By comparison, it is found that the pressure pulsation on the inlet of the impeller is the main cause of hydraulic induced vibration of the pump device, and it is found to have similar amplitude trend with the vertical vibration as the flow rates increases and large correlation coefficient with the horizontal vibration under high flow rates through time-domain analysis. By frequency-domain analysis, it is found that the main frequency of pressure pulsation is three multiplies of the shaft frequency, but it is one multiplies of vertical vibration, and it changes from one multiplies to three multiplies of horizontal vibration. Combining with the analysis of phase-flow rates characteristics of both pressure pulsation and vibration, it is concluded that, for the horizontal vibration, the frequency ingredient of one multiplies ranging from low to high flow rates and three multiplies removing from unstable and high flow rates zone are possibly induced by pressure pulsation on the inlet of impeller, while for the vertical vibration, the frequency ingredient of one multiplies under design flow rates and high flow rates are possibly induced by pressure pulsation on the inlet of impeller. Both the horizontal and vertical vibrations with frequency of two multiplies have little relationship with the pressure pulsation on the inlet of impeller.

Download Full-text

Study on the Performance Improvement of Axial Flow Pump’s Saddle Zone by Using a Double Inlet Nozzle

Water ◽

10.3390/w12051493 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1493

Author(s):

Weidong Cao ◽

Wei Li

Keyword(s):

Flow Rate ◽

Three Dimensional ◽

Axial Flow ◽

Rotating Stall ◽

Stable Operation ◽

Inlet Section ◽

Pump Impeller ◽

Rate Condition ◽

Axial Flow Pump ◽

Flow Pump

The operating range of axial flow pumps is often constrained by the onset of rotating stall. An improved method using a double inlet nozzle to stabilize the performance curve is presented in the current study; a single inlet nozzle and three kinds of double inlet nozzle with different rib gap widths at the inlet of axial flow pump impeller were designed. Three dimensional (3D) incompressible flow fields were simulated, and the distributions of turbulence kinetic energy and velocity at different flow rates located at the inlet section, as well as the pressure and streamline in the impeller, were obtained at the same time. The single inlet nozzle scheme and a double inlet nozzle scheme were studied; the experimental and numerical performance results show that although the cross section is partly blocked in the double inlet nozzle, the head and efficiency do not decline at stable operation flow rate. On small flow rate condition, the double inlet nozzle scheme effectively stabilized the head-flow performance, whereby the block induced by the backflow before the impeller was markedly improved by using a double inlet nozzle. It has also been found that the rib gap width impacts the efficiency curve of the axial flow pump.

Download Full-text

Investigation of the Flow Field in the Vicinity of an Axial Flow Fan During Low Flow Rates

Volume 1A: Aircraft Engine; Fans and Blowers ◽

10.1115/gt2014-25927 ◽

2014 ◽

Cited By ~ 2

Author(s):

Francois G. Louw ◽

Theodor W. von Backström ◽

Sybrand J. van der Spuy

Keyword(s):

Flow Field ◽

Numerical Simulations ◽

Flow Rate ◽

Axial Flow ◽

Operating Conditions ◽

Design Flow ◽

Low Flow ◽

Axial Flow Fan ◽

Free Vortex ◽

Flow Rates

Large axial flow fans are used in forced draft air cooled heat exchangers (ACHEs). Previous studies have shown that adverse operating conditions cause certain sectors of the fan, or the fan as a whole to operate at very low flow rates, thereby reducing the cooling effectiveness of the ACHE. The present study is directed towards the experimental and numerical analyses of the flow in the vicinity of an axial flow fan during low flow rates. This is done to obtain the global flow structure up and downstream of the fan. A near-free-vortex fan, designed for specific application in ACHEs, is used for the investigation. Experimental fan testing was conducted in a British Standard 848, type A fan test facility, to obtain the fan characteristic. Both steady-state and time-dependent numerical simulations were performed, depending on the operating condition of the fan, using the Realizable k-ε turbulence model. Good agreement is found between the numerically and experimentally obtained fan characteristic data. Using data from the numerical simulations, the time and circumferentially averaged flow field is presented. At the design flow rate the downstream fan jet mainly moves in the axial and tangential direction, as expected for a free-vortex design criteria, with a small amount of radial flow that can be observed. As the flow rate through the fan is decreased, it is evident that the down-stream fan jet gradually shifts more diagonally outwards, and the region where reverse flow occur between the fan jet and the fan rotational axis increases. At very low flow rates the flow close to the tip reverses through the fan, producing a small recirculation zone as well as swirl at certain locations upstream of the fan.

Download Full-text

Investigation on the Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump

Journal of Fluids Engineering ◽

10.1115/1.4046376 ◽

2020 ◽

Vol 142 (7) ◽

Author(s):

Chaoyue Wang ◽

Fujun Wang ◽

Yuan Tang ◽

Benhong Wang ◽

Zhifeng Yao ◽

...

Keyword(s):

Guide Vane ◽

Pressure Fluctuations ◽

Axial Flow ◽

Maximum Amplitude ◽

Separation Flow ◽

Suction Surface ◽

Corner Separation ◽

Axial Flow Pump ◽

Velocity Moment ◽

Flow Pump

Abstract Stator corner separation flow existing in the guide-vane domain has significant effects on the characteristics of an axial-flow pump. The objective of this paper is to investigate the vortical structures in stator corner separation flow. Transient numerical simulation with a proof experiment was conducted for an axial-flow pump. Structural features of the vortices and their effects on velocity moment attenuation and pressure fluctuations in the guide-vane domain were analyzed. Horn-like vortices are found in the stator corner separation flow. A full cycle of the horn-like vortex evolution, “inception-growth-development-decay,” is presented. During this transit process, the vortex tube is gradually elongated and deformed, which forms an oblique separation line on the vane suction surface. High velocity moment always exists in the flow passages of the guide-vane domain, and the uniformity of main flows is gradually reduced. Meanwhile, periodic pressure fluctuations arise. The maximum amplitude of pressure fluctuations in the flow passages occurs in the region where the horn-like vortex cores at the “growth” stage lie in, which is approximately 3.39 times higher than that in the vaneless region between the impeller and guide-vane. The dominant frequency of pressure fluctuations in the flow passages is approximately 0.75 times the rotating frequency, which is close to the frequency of the full cycle of the horn-like vortex evolution. Horn-like vortices have remarkable effects on the flow fields, and more attention should be paid to them.

Download Full-text