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.

An Investigation on Real and Imaginary Energy Transfer Mechanism Caused in Rotating Flow Passage of Centrifugal Pump

2005 ◽  
Author(s):  
Takaharu Tanaka ◽  
Chao Liu
Keyword(s):  
Energy Transfer ◽  
Physical Properties ◽  
Centrifugal Pump ◽  
Rotational Motion ◽  
Rotating Flow ◽  
Physical Parameters ◽  
Energy Transfer Mechanism ◽  
Flow Passage ◽  
Different Types ◽  
Force Velocity

Hydraulic energy is constructed from real and imaginary energies. Their acting directions are normal to each other. Their physical properties are quite different. All the physical parameters, such as force, velocity, and acceleration therefore consist of two different type real and imaginary functions. Physically, there are three different types of fluid particles rotational motion: straightly forward non-rotational motion, which is based upon kinetic real physical parameters, circularly forward rotational motion, which is based upon un-kinetic imaginary physical parameters, and their combined rotational motion. Their interrelation is shown in diagram.

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.

Fluid Particles Fundamental Movement in Rotating Flow Passage of Turbomachinery

2002 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Energy Input ◽  
Radial Direction ◽  
Leading Edge ◽  
Energy Output ◽  
Rotating Flow ◽  
Trailing Edge ◽  
Flow Passage ◽  
Impeller Outlet ◽  
Water Turbine ◽  
Tangential Forces

Hydraulic energy balance is held in radial direction at trailing edge of impeller outlet in pump and at leading edge of impeller inlet in water turbine. Hydraulic energy output at trailing edge of impeller outlet in pump and hydraulic energy input at leading edge of impeller inlet in water turbine appear in the form of product of fluid particle’s rotational and tangential movement. The rate of hydraulic energy head H and flow rate Q is equivalent to the rate of centrifugal and tangential forces, hence equivalent to rate of rotational and tangential distances of which fluid particle had moved at those sections.

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.

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.

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.

Interrelation Between Mechanical Energy Supply and Flow Rate in Practical Operation of Centrifugal Pump

2004 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Energy Supply ◽  
Mechanical Energy ◽  
Rotating Flow ◽  
Centripetal Force ◽  
Impeller Blade ◽  
Flow Passage ◽  
Practical Operation ◽  
Pump Head ◽  
Fluid Particles ◽  
Remaining Time

Pump head plays an external centripetal force and balanced with imaginary centrifugal force. Fluid particles circularly forward tangential movement in the direction tangent increases with the fluid particles remaining time increase in the rotating flow passage. And fluid particles circularly forward tangential movement in the direction tangent is caused by the imaginary mechanical force perpendicular to rotational radius. Therefore, mechanical energy supply is proportional to fluid particles remaining time in the rotating flow passage of impeller blade to cause the circularly forward tangential movement.

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.

Hydraulic Design of Inlet Guide Vane and its Full Flow Passage Numerical Simulation on Centrifugal Pump

2014 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Zhenlin Li ◽  
Xin Zhou ◽  
Zizhe Wang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Guide Vane ◽  
Hydraulic Performance ◽  
Design Flow ◽  
Inlet Guide Vane ◽  
Hydraulic Efficiency ◽  
Flow Passage ◽  
Setting Angle ◽  
Hydraulic Design

In order to effectively improve hydraulic performance of centrifugal pump on off-conditions, the hydraulic design of inlet guide vane (IGV) was completed by adopting two dimensional theory in-house code based on one kind of IS series of centrifugal pump, which can achieve pre-whirl regulation of centrifugal pump. During design process the trailing edge of vane is assumed as equal velocity moment condition, and the distribution of vane setting angle along meridional streamline is also given as a quartic function firstly, the camber line is then drawn by point-by-point integration method and thickened at both sides along circumferential direction. With local vortex dynamics diagnosis theory, the optimal improvement of vane space shape can be finished by adjusting the design parameters of vane setting angle distribution coefficient ap. The full flow passage numerical simulations of centrifugal pump with IGV device are completed to analyze the influence of pre-whirl regulation on hydraulic performance of centrifugal pump under various pre-whirl angles. The results show that the pre-whirl regulation can improve the hydraulic performance of centrifugal pump on off-conditions. Under the positive pre-whirl regulation conditions, the best efficient point shift to small flow rate zone, and under the negative pre-whirl regulation conditions it moves to large flow rate zone. Compared with the pump without IGV device at the same flow rate condition of 0.8Q (Q the design flow rate), the hydraulic efficiency of centrifugal pump with IGV device improves obviously and reaches up to 1.43%. Meanwhile compared with that installed with the straight vanes designed based on the traditional theory, the inner flow field of centrifugal pump with the designed vanes improves and the overall hydraulic efficiency of centrifugal pump is somewhat increased.

Sign in / Sign up

Export Citation Format

Share Document