Theoretical Investigation on Flow Rate at the Maximum Efficiency Point in the Design of Impeller Blade in Centrifugal Pump

2004 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Pump ◽  
Theoretical Investigation ◽  
Flow Rate ◽  
Tangential Velocity ◽  
Maximum Efficiency ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Peripheral Velocity ◽  
Impeller Outlet ◽  
Fluid Particles

This paper presents a theoretical investigation of the flow rate at the maximum efficiency point in the design of impeller blade in centrifugal pump. An energy balance was performed at the trailing edge of impeller outlet in the rotating flow passage of centrifugal pump. The evaluation shows that, when the fluid particles straight forward tangential velocity is one third of the impeller blade’s peripheral velocity and the fluid particles circular forward tangential velocity is two third of the impeller blade’s peripheral velocity at the trailing edge of the impeller outlet, the maximum hydraulic energy output, that is, the maximum efficiency point is obtained.

scholarly journals Pressure Fluctuation Reduction of a Centrifugal Pump by Blade Trailing Edge Modification

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1408 ◽  
Author(s):  
Bin Huang ◽  
Guitao Zeng ◽  
Bo Qian ◽  
Peng Wu ◽  
Peili Shi ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Side ◽  
Centrifugal Pumps ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Blade Passing Frequency ◽  
Impeller Outlet ◽  
Edge Profile ◽  
Edge Trimming

The pressure fluctuation inside centrifugal pumps is one of the main causes of hydro-induced vibration, especially at the blade-passing frequency and its harmonics. This paper investigates the feature of blade-passing frequency excitation in a low-specific-speed centrifugal pump in the perspective of local Euler head distribution based on CFD analysis. Meanwhile, the relation between local Euler head distribution and pressure fluctuation amplitude is observed and used to explain the mechanism of intensive pressure fluctuation. The impeller blade with ordinary trailing edge profile, which is the prototype impeller in this study, usually induces wake shedding near the impeller outlet, making the energy distribution less uniform. Because of this, the method of reducing pressure fluctuation by means of improving Euler head distribution uniformity by modifying the impeller blade trailing edge profile is proposed. The impeller blade trailing edges are trimmed in different scales, which are marked as model A, B, and C. As a result of trailing edge trimming, the impeller outlet angles at the pressure side of the prototype of model A, B, and C are 21, 18, 15, and 12 degrees, respectively. The differences in Euler head distribution and pressure fluctuation between the model impellers at nominal flow rate are investigated and analyzed. Experimental verification is also conducted to validate the CFD results. The results show that the blade trailing edge profiling on the pressure side can help reduce pressure fluctuation. The uniformity of Euler head circumferential distribution, which is directly related to the intensity of pressure fluctuation, is improved because the impeller blade outlet angle on the pressure side decreases and thus the velocity components are adjusted when the blade trailing edge profile is modified. The results of the investigation demonstrate that blade trailing edge profiling can be used in the vibration reduction of low specific impellers and in the engineering design of centrifugal pumps.

Interrelation Between Fluid Particles Rotational Motion in Rotating Flow Passage of Centrifugal Pump and Overall Efficiency

Volume 3 ◽  
2004 ◽  
Author(s):  
Takaharu Tanaka ◽  
Chao Liu
Keyword(s):  
Centrifugal Pump ◽  
Rotational Motion ◽  
Rotating Flow ◽  
Energy Losses ◽  
Trailing Edge ◽  
Flow Passage ◽  
Impeller Outlet ◽  
Overall Efficiency ◽  
Fluid Particles ◽  
The Way

Main purpose of investigation has been put on the hydraulic energy losses caused in the rotating flow passage of centrifugal pump. Result of discussion shows that fundamental poor efficiency is brought by the fluid particles poor rotational motion at the trailing edge of impeller outlet, including the rotational motion caused in the flow passage between impeller blades rather than the hydraulic energy losses caused in the rotating flow passage. Therefore, our main purpose of investigation has to be put on the way rather to the fluid particles rotational motion caused at the trailing edge of impeller outlet and that caused between impeller blades.

scholarly journals Effects of Flow Rate and Viscosity on Slip Factor of Centrifugal Pump Handling Viscous Oils

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Tangential Velocity ◽  
Low Flow ◽  
Liquid Viscosity ◽  
Blade Angle ◽  
Pump Impeller ◽  
Slip Factor ◽  
Hydraulic Design ◽  
Impeller Outlet

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.

An Investigation on Velocity Triangle Applied to Fluid Particle at Rotating Flow Passage of Impeller Blade in Centrifugal Pump

Volume 1 ◽  
2004 ◽  
Author(s):  
Takaharu Tanaka ◽  
Chao Liu
Keyword(s):  
Flow Rate ◽  
Tangential Velocity ◽  
Maximum Flow ◽  
Maximum Flow Rate ◽  
Rotating Flow ◽  
Impeller Blade ◽  
Flow Passage ◽  
Rotating Speed ◽  
Velocity Triangle ◽  
Fluid Particles

Although impeller blades rotational speed is kept constant for the change in flow rate, fluid particles rotating speed varies by the flow rate. Fluid particles circularly forward tangential velocity becomes zero at the maximum flow rate and the maximum at the flow rate zero. While fluid particles fundamental straightly forward tangential velocity normal to rotational radius becomes the maximum at the maximum flow rate and zero at flow rate zero.

A Consideration on Energy Transfer Mechanism Caused Between Impeller Blade and a Fluid Particle in Centrifugal Pump

2002 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Pump ◽  
Centrifugal Force ◽  
Flow Rate ◽  
Fluid Particle ◽  
Rotating Flow ◽  
Energy Transfer Mechanism ◽  
Forward Movement ◽  
Impeller Blade ◽  
Impeller Outlet ◽  
Centripetal Forces

Impeller blade’s rotational motion causes centrifugal force on fluid particle. It directs radial outward. However, the flow rate, that is, radial outward flow is not caused by centrifugal force in centrifugal pump. Tangential forward force, which is in the direction perpendicular to rotational radius, causes tangential forward movement on fluid particle under the radial balance of centrifugal and centripetal forces in the rotating flow passage of centrifugal pump and it causes the flow rate. And the head is caused by centrifugal force and equivalent to centripetal force, which acts on fluid particle radial inward. Which is equivalent to external force at the trailing edge of impeller outlet.

scholarly journals Experimental Analysis on Pressure Fluctuation Characteristics of a Centrifugal Pump with Vaned-Diffuser

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 126
Author(s):  
Houlin Liu ◽  
Ruichao Xia ◽  
Kai Wang ◽  
Yucheng Jing ◽  
Xianghui He
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Dominant Frequency ◽  
Design Flow ◽  
Signal Source ◽  
Vaned Diffuser ◽  
Impeller Outlet ◽  
Variation Tendency ◽  
Design Flow Rate

Experimental measurements to analyze the pressure fluctuation performance of a centrifugal pump with a vaned-diffuser, which its specific speed is 190. Results indicate that the main cause of pressure fluctuation is the rotor-stator interference at the impeller outlet. The head of the pump with vaned-diffuser at the design flow rate is 15.03 m, and the efficiency of the pump with a vaned-diffuser at the design flow rate reaches 71.47%. Pressure fluctuation decreases gradually with increasing distance from the impeller outlet. Along with the increase of the flow rate, amplitude of pressure fluctuation decreases. The amplitude of pressure fluctuation at the measuring points near the diffusion section of the pump body is larger than other measuring points. The variation tendency of pressure fluctuation at P1–P10 is the same, while there are wide frequency bands with different frequencies. The dominant frequency of pressure fluctuation is the blade passing frequency. The rotor-stator interference between the impeller and the vaned-diffuser gives rise to the main signal source of pressure fluctuation.

scholarly journals Analysis of the number and angle of the impeller blade to the performance of centrifugal pump

2021 ◽  
pp. 62-68
Author(s):  
Sugeng Hadi Susilo ◽  
Agus Setiawan
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Flow Simulation ◽  
Maximum Output ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Pump Performance ◽  
Solid Works ◽  
Discharge Pressure

The paper discusses the performance of the pump in relation to the impeller. The impeller section is determined by the number and angle of the blades. Therefore, the purpose of this study was to analyze the role of the number and angle of impeller blades on the performance (discharge and discharge pressure) of centrifugal pumps based on experiments and simulations. The method used is experiment and simulation. Using a centrifugal pump type GWP 20/4 SW, Maximum Output: 6.5 HP/3500 rpm, Inlet/Outlet: 2 Inch, Dimensions: 475x375x370 mm. Experiments and simulations by varying the number of blades 2, 4, and 6 with a blade tilt angle of 130°, 150°, and 160°. For flow simulation using solid works program. The results show that pump performance is related to discharge pressure, impeller with 2-blades and an angle of 130° the pressure increases 0.45–2.45 bar, for 150° increases 0.14–2.96 bar, and 160° increases 0.29–3.07 bars. For a 4-blade impeller and an angle of 130°, the pressure increases by 0.48–3.12 bar, for 150° it increases by 0.39–3.39 bar, and for 160° it increases by 0.36–3.48 bar. While the impeller for 6-blades with an angle of 130° the pressure increases from 0.6 bar to 3.72 bar, for 150° increases from 1.36 to 4.34 bar, and 160° increases by 0.36–4.74 bar. While it related pump performance to flow rate, increasing the number of blades causes a decrease in flow rate. The highest flow rate is in a 2-blade impeller with a blade angle of 130° is 404.91 l/s. The lowest flow rate is on a 6-blade impeller with an angle of 160° is 279.66 l/s

Fluid Particle’s Rotational Speed at the Trailing Edge of Impeller Outlet of Centrifugal Pump

2003 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Force ◽  
Flow Rate ◽  
Mechanical Energy ◽  
Fluid Particle ◽  
Rotating Flow ◽  
Centripetal Force ◽  
Impeller Blade ◽  
Flow Passage ◽  
Impeller Outlet ◽  
Pump Head

Mechanical force caused by mechanical energy acts real and imaginary forces on impeller blade. Therefore, impeller blade moves in the direction of real force, straightly forward in the direction of tangent perpendicular to rotational radius and the direction of imaginary force, circularly forward in the direction of tangent perpendicular to rotational radius. Former real movement causes on fluid particle radial outward movement, resulting to flow rate Q. Latter imaginary movement causes on fluid particle a rotational motion under the external centripetal and imaginary centrifugal force, resulting to pump head. Pump head is equivalent to external centripetal force and balanced with imaginary centrifugal force in the rotating flow passage.

Fluid Particles Straightly Forward and Circularly Forward Movements in the Direction of Tangent at Trailing Edge of Impeller Outlet in Centrifugal Turbomachinery

2003 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Centrifugal Force ◽  
Flow Rate ◽  
Rotational Motion ◽  
Mechanical Energy ◽  
Centripetal Force ◽  
Impeller Outlet ◽  
Water Turbine ◽  
Fluid Particles ◽  
Centripetal Forces ◽  
Acting Force

Flow rate, which is caused in the direction radial outward in pump and radial inward in water turbine, is caused by the fluid particles straightly forward tangential movement in the direction of acting force perpendicular to impeller blades rotational radius. Impeller blades rotational motion is caused under the radial balance of centrifugal and centripetal forces. Centrifugal force is caused by the transferred energy from mechanical to hydraulic energy in pump and from hydraulic to mechanical energy in water turbine. Centripetal force is equivalent to discharge head in pump and equivalent to suction head in water turbine.

Quantitative Visualization of the Flow Within the Volute of a Centrifugal Pump. Part B: Results and Analysis

1992 ◽  
Vol 114 (3) ◽  
pp. 396-403 ◽  
Author(s):  
R. Dong ◽  
S. Chu ◽  
J. Katz
Keyword(s):  
Angular Momentum ◽  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Momentum Flux ◽  
Inflow Rate ◽  
Impeller Blade ◽  
Velocity Fluctuations ◽  
Quantitative Visualization ◽  
The Mean

PDV is used for measuring the velocity within the volute of a centrifugal pump at different impeller blade orientations, on and off design conditions. It is demonstrated that the flow is “pulsating” and depends on the location of the blade relative to the tongue. The leakage also depends on blade orientation and increases with decreasing flow rate. The velocity near the impeller is dominated by the jet/wake phenomenon. Differences in the outflux from the impeller, resulting from changes inflow rate, occur primarily near the exit. Away from the tongue the distributions of vθ mostly agrees with the assumption that vθ ∝ 1/r. Sites prone to high velocity fluctuations include the blade wake, interface between the jet and the wake and near the tongue. Angular momentum and kinetic energy fluxes, turbulent stresses and tubulence production are also computed. It is shown that at the same θ the momentum flux can increase near the impeller and decrease at the perimeter. Consequently, the mean flux cannot be used for estimating conditions near the impeller. Torques caused by τrθ and τθθ can be as high as 2 and 5 percent of the change in angular momentum flux, respectively.

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