scholarly journals Effect of Blade Outlet Angle on Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blade

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Yasuyuki Nishi ◽  
Junichiro Fukutomi
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Static Pressure ◽  
Hydrodynamic Forces ◽  
Centrifugal Impeller ◽  
Leakage Flow ◽  
Axial Thrust ◽  
Outlet Angle ◽  
Closed Type ◽  
Radial Thrust

Geometrically, the single-blade centrifugal impeller, commonly used today as a sewage pump, is not axially symmetric. For this reason, the static pressure around the impeller fluctuates greatly when the impeller is rotating, and not only the radial thrust but also the axial thrust shows large fluctuations. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces. In this study, we investigated the unsteady hydrodynamic forces in a closed-type centrifugal pump with a single blade for different blade outlet angles using a numerical analysis that takes into account both experiment and the leakage flow. The results clearly showed the effect of the blade outlet angle on that act on the impeller. The root-mean-square value of the fluctuating component of the total radial thrust was roughly the same for whichever impeller at low flow rate, but at high flow rates, the value increased for impellers with larger blade outlet angles. Moreover, when the leakage flow rate increased with increasing static pressure around the impeller, such that the rear and front shroud parts were subject to high pressure, the absolute value of the axial thrust on both these parts increased.

scholarly journals Component Analysis of Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blades of Different Blade Outlet Angles

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Yasuyuki Nishi ◽  
Junichiro Fukutomi
Keyword(s):  
Numerical Analysis ◽  
Flow Rate ◽  
Hydrodynamic Force ◽  
Leakage Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Outlet Angle ◽  
Closed Type ◽  
Radial Thrust ◽  
Sewage Systems

Single-blade centrifugal impellers for sewage systems undergo both unsteady radial and axial thrusts. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces and determine the generation mechanism behind them. In this study, we conducted component analyses of radial and axial thrusts of closed, single-blade centrifugal pumps with different blade outlet angles by numerical analysis while considering leakage flow. The results revealed the effect of the blade outlet angle on the components of radial and axial thrusts. For increased flow rates, the time-averaged values of the pressure component were similar for all impellers, although its fluctuating components were higher for impellers with larger blade outlet angles. Moreover, the fluctuating inertia component of the impeller with a blade outlet angle of 8° decreased as the flow rate increased, whereas those with 16° and 24° angles increased. Therefore, the radial thrust on the hydraulic part was significantly higher for impellers with high blade outlet angles.

Radial Thrust of Single-Blade Centrifugal Pump

2011 ◽  
Author(s):  
Yasuyuki Nishi ◽  
Junichiro Fukutomi ◽  
Ryota Fujiwara
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Design Flow ◽  
Centrifugal Impeller ◽  
Cfd Analysis ◽  
Shearing Stress ◽  
Pump Operation ◽  
Grand Total ◽  
Conservation Of Momentum ◽  
Radial Thrust

A single-blade centrifugal pump is widely used as a sewage pump. However, a single-blade is acted on by a large radial thrust during the pump operation because of the geometrical axial asymmetry of the impeller. Therefore to secure the pump reliability, it is necessary to grasp the radial thrust quantitatively and elucidate a behavior and a generation mechanism. This study investigated the radial thrust acting on a single-blade centrifugal impeller by an experiment and a CFD analysis, and the results clearly indicated the following facts. The fluctuating component of the radial thrust increased as the flow rate changed from the design flow rate to a partial or excessive flow rate. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum and pressure components by applying unsteady conservation of momentum to this impeller. The grand total of these components was in agreement with the radial thrust calculated by integrating the pressure and the shearing stress on the impeller surface. In addition the behavior of each component was shown and the effects of those components that gave to the radial thrust were clarified. The pressure component had the greatest effect on a time-averaged value and a fluctuating component of the radial thrust. The time-averaged value of the inertia component was approximately 0 even if the flow rate changed. But its fluctuating component had a magnitude nearly comparable to the pressure component at a partial flow rate and slightly decreased with increase of the flow rate.

scholarly journals Influence of Balance Hole Diameter on Leakage Flow of the Balance Chamber in a Centrifugal Pump

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wei Dong ◽  
Diyi Chen ◽  
Jian Sun ◽  
Yan Dong ◽  
Zhenbiao Yang ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Axial Force ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Vortex Motion ◽  
Internal Flow ◽  
Hole Diameter ◽  
Leakage Flow ◽  
Centrifugal Pumps ◽  
Axial Thrust

The balancing holes in centrifugal pumps with seals mounted in both suction and discharge sides are one of the approaches used by pump manufacturers to reduce the axial thrust. The balance hole diameter directly affects the axial force of the centrifugal pump. The flow characteristics in the balance chamber are closely related to the balance hole diameter. However, research is not very clear on the internal flow of the balanced chamber, due to the small axial and radial sizes and the complicated flow conditions in the chamber. In this paper, we analyzed the influence of the balance hole diameter on the liquid leakage rate, flow velocity, and vortex motion in the balance chamber. The results indicated that when the balance hole diameter was lower than the design value, the volume flow rate of leakage flow was proportional to the diameter. The liquid flow rate and vortex distribution rules in the balance chamber were mainly associated with the coeffect of radial leakage flow in the rear sealing ring interval and the axial balance hole leakage flow. The research has revealed the mechanisms of leakage flow of the balance chamber in the centrifugal pump and that this is of great significance for accurate calculation and balancing of the axial force.

Experimental Study of the Flow in the Suction Pipe of a Centrifugal Pump at Partial Flow Rates in Unsteady Conditions

1999 ◽  
Vol 121 (3) ◽  
pp. 291-295 ◽  
Author(s):  
S. Bolpaire ◽  
J. P. Barrand
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Static Pressure ◽  
Pressure Measurements ◽  
Flow Rates ◽  
Suction Pipe ◽  
Start Up ◽  
Test Loop ◽  
Fast Start ◽  
Operational Range

The operational range and the performances of pumps are limited by the occurrence of backflow and prerotation in the suction pipe as the flow rate is reduced. This paper presents the study of static pressure measurements and visualizations in the suction pipe, near the inlet of a centrifugal pump, at partial flow rates, in steady conditions, and during a fast start-up of the pump. The tests were carried out in water on the DERAP© test loop of the ENSAM Lille laboratory. Standard methods allowed to determine the recirculation critical flow rate. A visualization method showed that the axial extent of the recirculation and the prerotation with the flow rate is considerably reduced during a fast start-up compared to steady conditions.

1108 Effect of the Impeller Outlet Angle on Radial Thrust of Single-Blade Centrifugal Pump

2009 ◽  
Vol 2009 (0) ◽  
pp. 357-358
Author(s):  
Yasuyuki NISHI ◽  
Ryota FUJIWARA ◽  
Yoshikado HOTTA ◽  
Junichiro FUKUTOMI ◽  
Toru SHIGEMITSU
Keyword(s):  
Centrifugal Pump ◽  
Outlet Angle ◽  
Impeller Outlet ◽  
Radial Thrust

scholarly journals The Numerical Analysis of Radial Thrust and Axial Thrust in the Screw Centrifugal Pump

2012 ◽  
Vol 31 ◽  
pp. 176-181 ◽  
Author(s):  
Wei Han ◽  
Wei Maa ◽  
Rennian Li ◽  
Qifei Li
Keyword(s):  
Numerical Analysis ◽  
Centrifugal Pump ◽  
Axial Thrust ◽  
Radial Thrust

Flow at the Centrifugal Pump Impeller Exit With Circumferential Distortion of the Outlet Static Pressure

2004 ◽  
Vol 126 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Soon-Sam Hong ◽  
Shin-Hyoung Kang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Total Pressure ◽  
Static Pressure ◽  
Mean Flow ◽  
Simple Method ◽  
Local Flow ◽  
Flow Angle ◽  
Flow Parameters ◽  
Relative Flow

The effects of circumferential outlet distortion of a centrifugal pump diffuser on the impeller exit flow were investigated. A fence with sinusoidal width variation was installed at the vaneless diffuser exit. The flow field was measured at the impeller exit with and without the fence, using a hot film probe and an unsteady pressure sensor. Flow parameters varied with the circumferential position and the mean flow parameters plotted against the local flow rate at each circumferential position showed loops along the quasi-steady curves, which were obtained from the result without the fence. Simple theoretical calculations were used to predict the velocity components at the impeller exit with the relative flow angle or total pressure assumed. Good result was obtained when the relative flow angle was assumed to vary quasi-steadily, not constant with the local flow rate. The radial velocity was also reasonably predicted when the total pressure was assumed to vary quasi-steadily. A simple method is proposed to predict the impeller exit flow with downstream blockage in two-step sequence: the first step deals with the diffuser alone to obtain static pressure distribution at the diffuser inlet, while the second step deals with the impeller alone to obtain velocity components distribution at the impeller exit.

Experimental Investigation on Diffuser Rotating Stall in a Three-Stage Centrifugal Pump

2017 ◽  
Author(s):  
Taiki Takamine ◽  
Satoshi Watanabe ◽  
Daichi Furukawa ◽  
Hiroyoshi Watanabe ◽  
Kazuyoshi Miyagawa
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Suction Side ◽  
Rotating Stall ◽  
Leakage Flow ◽  
The Troubles ◽  
Second Stage ◽  
The Third ◽  
Shaft System ◽  
Third Stage

Rotating stall phenomenon frequently causes the troubles such as vibrations acting on the shaft system and reduces the reliability of turbomachines. In the present study, the diffuser rotating stall in a three-stage centrifugal pump was experimentally studied. Special emphasises were placed on the geometrical conditions; an axial offset of rotor against the stationary part, which might be unavoidable due to accumulation of geometrical tolerances and assembling errors., and the radial clearances of annular leakage paths which increases the thru-flow rate at the impellers and the first and second stage diffusers. As a result, with the rotor axial offset to the suction side, the rotating stall appeared only at the third stage diffuser, while with that to the discharge side, the rotating stall was more significant. By enlarging the leakage flow passages at the inter-stage bush and the balancing flow channel, the onset range of rotating stall became narrower in the first and second stage diffusers, which was well explained by the increase of the thru-flow rate. On the other hand, with the enlarged leakage passage at the liner ring, the onset range became slightly wider.

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