Flow Characteristics of a Centrifugal Pump

1994 ◽  
Vol 116 (2) ◽  
pp. 303-309 ◽  
Author(s):  
C. H. Liu ◽  
C. Vafidis ◽  
J. H. Whitelaw
Keyword(s):  
Refractive Index ◽  
Centrifugal Pump ◽  
Radial Flow ◽  
Flow Characteristics ◽  
Secondary Flows ◽  
Laser Doppler Velocimeter ◽  
Suction Surface ◽  
Tip Leakage ◽  
Tip Velocity ◽  
Working Liquid

Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the transparent casing to facilitate the use of a laser-Doppler velocimeter. The flows in the impeller passages were found to depart from the curvature of the blade surfaces at off-design conditions with separation from the suction surface and from the shroud. Secondary flows from the suction to pressure surfaces were dominated by the influences of the relative motion between the shroud and impeller surfaces and the tip leakage. Geometric differences of 0.5 mm and one degree in spacing of the four blades caused differences in passage velocity of up to 6 percent of the impeller tip velocity close to the design flowrate and up to 16 percent at the lowest discharge. The flowrate from each impeller passage varied with volute circumferential position by up to 25 percent at an off-design flowrate. Poor matching of the impeller and volute at off-design conditions caused swirl and separation in the inlet and exit pipes.

Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions

2004 ◽  
Vol 128 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Nicole L. Key ◽  
Tony Arts
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Cascade Arrangement ◽  
Oil Flow ◽  
Blade Tip ◽  
Tip Velocity

The tip leakage flow characteristics for flat and squealer turbine tip geometries are studied in the von Karman Institute Isentropic Light Piston Compression Tube facility, CT-2, at different Reynolds and Mach number conditions for a fixed value of the tip gap in a nonrotating, linear cascade arrangement. To the best knowledge of the authors, these are among the very few high-speed tip flow data for the flat tip and squealer tip geometries. Oil flow visualizations and static pressure measurements on the blade tip, blade surface, and corresponding endwall provide insight to the structure of the two different tip flows. Aerodynamic losses are measured for the different tip arrangements, also. The squealer tip provides a significant decrease in velocity through the tip gap with respect to the flat tip blade. For the flat tip, an increase in Reynolds number causes an increase in tip velocity levels, but the squealer tip is relatively insensitive to changes in Reynolds number.

Flowfield Measurements in the Endwall Region of a Stator Vane

1999 ◽  
Author(s):  
M. B. Kang ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Suction Side ◽  
Secondary Flows ◽  
Laser Doppler Velocimeter ◽  
Transfer Coefficients ◽  
Suction Surface ◽  
Numerical Predictions ◽  
High Heat Transfer ◽  
Passage Vortex ◽  
Stator Vane

A first stage stator vane experiences high heat transfer rates particularly near the end wall where strong secondary flows occur. In order to improve numerical predictions of the complex endwall flow at low speed conditions, benchmark quality experimental data are required. This study documents the flowfield in the endwall region of a stator vane that has been scaled up by a factor of nine while matching an engine exit Reynolds number of Reex = 1.2·106. Laser Doppler velocimeter (LDV) measurements of all three components of the mean and fluctuating velocities are presented for several flow planes normal to the turbine vane. Measurements indicate that downstream of the minimum static pressure location on the suction surface of the vane, an attenuated suction side leg of the horseshoe vortex still exists. At this location, the peak turbulent kinetic energy coincides with the center of the passage vortex location. These flowfield measurements were also related to previously reported convective heat transfer coefficients on the endwall showing that high Stanton numbers occur where the passage vortex brings mainstream fluid towards the vane surface.

scholarly journals Prediction of Cavitation Evolution and Cavitation Erosion on Centrifugal Pump Blades by the DCM-RNG Method

Scanning ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Han Zhu ◽  
Ning Qiu ◽  
Chuan Wang ◽  
Qiaorui Si ◽  
Jie Wu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Cavitation Erosion ◽  
Flow Characteristics ◽  
Prediction Method ◽  
Pressure Change ◽  
Correction Method ◽  
Centrifugal Pumps ◽  
Suction Surface ◽  
Term Operation ◽  
Pressure Surface

Cavitation can reduce the efficiency and service life of the centrifugal pumps, and a long-term operation under cavitation conditions will cause cavitation damage on the surface of material. The external characteristic test of the IS65-50-174 single-stage centrifugal pump was carried out. Moreover, the cavitation mechanism under specific conditions was analyzed by numerical simulation. Considering the macroscopic cavitation flow structure in the centrifugal pump, three different cavitation erosion prediction methods were used to predict the erodible areas. The results show that the calculation results obtained by the density correction method (DCM) can well match the flow characteristics of the centrifugal pump under the rated conditions. When the centrifugal pump head drops by 3%, cavitation mainly occurs on the suction surface, and the cavity on the pressure surface is mainly concentrated near the front cover. The cavitation prediction method based on the time derivation of pressure change is not suitable for centrifugal pumps, while the prediction result of the erosive power method is more reasonable than the others. At time 0.493114 s, the maximum erosive power appears on the blade near the volute tongue, and its value is 1.46 e − 04  W.

An Experimental Study of Heat Transfer in a Large-Scale Turbine Rotor Passage

1992 ◽  
Author(s):  
Michael F. Blair
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Large Scale ◽  
Leading Edge ◽  
High Heat ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Suction Surface ◽  
Tip Leakage ◽  
High Heat Transfer

An experimental study of the heat transfer distribution in a turbine rotor passage was conducted in a large–scale, ambient temperature, rotating turbine model. Meat transfer was measured for both the full–span suction and pressure surfaces of the airfoil as well as for the hub endwall surface. The objective of this program was to document the effects of flow three–dimensionality on the heat transfer in a rotating blade row (vs. a stationary cascade). Of particular interest were the effects of the hub and tip secondary flows, tip leakage and the leading–edge horseshoe vortexsystem. The effect of surface roughness on the passage heat transfer was also investigated. Midspan results are compared with both smooth–wall and rough–wall finite–difference two dimensional heat transfer predictions. Contour maps of Stanton number for both the rotor airfoil and endwall surfaces revealed numerous regions of high heat transfer produced by the three dimensional flows within the rotor passage. Of particular importance are regions of local enhancement (as much as 100% over midspan values) produced on the airfoil suction surface by the secondary flows and tip–leakage vortices and on the hub endwall by the leading–edge horseshoe vortex system.

Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions

2004 ◽  
Author(s):  
Nicole L. Key ◽  
Tony Arts
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Cascade Arrangement ◽  
Oil Flow ◽  
Blade Tip ◽  
Tip Velocity

The tip leakage flow characteristics for flat and squealer turbine tip geometries are studied in the von Karman Institute Isentropic Light Piston Compression Tube facility, CT-2, at different Reynolds and Mach number conditions for a fixed value of the tip gap in a non-rotating, linear cascade arrangement. To the best knowledge of the authors, these are among the very few high-speed tip flow data for the flat tip and squealer tip geometries. Oil flow visualizations and static pressure measurements on the blade tip, blade surface, and on the corresponding endwall provide insight to the structure of the two different tip flows. Aerodynamic losses are measured for the different tip arrangements, also. The squealer tip provides a significant decrease in velocity through the tip gap with respect to the flat tip blade. For the flat tip, an increase in Reynolds number causes an increase in tip velocity levels, but the squealer tip is relatively insensitive to change in Reynolds number.

scholarly journals Numerical Simulation of Internal Flow Field of Self-Designed Centrifugal Pump

2021 ◽  
Vol 2097 (1) ◽  
pp. 012017
Author(s):  
Xin Wang ◽  
Jun Zhang ◽  
Zongshun Li
Keyword(s):  
Centrifugal Pump ◽  
Turbulence Model ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Suction Surface ◽  
Sst Turbulence Model ◽  
Rng Turbulence Model ◽  
Pump Cavity ◽  
Gas Volume

Abstract The two self-designed of centrifugal pump with small vane and centrifugal pump without small vane were simulated numerically to select a centrifugal pump with higher efficiency. The internal flow characteristics of the centrifugal pump was simulated by using Reynolds time-averaged N-S equation and RNG turbulence model to obtain pressure and velocity distribution and the cavitation characteristics were simulated by using SST turbulence model and Schnerr-Sauer cavitation model to obtain the gas volume fraction distribution. The results show that at the same flow rate, the change of velocity in the pump cavity of centrifugal pump with vane is smoother and the gas volume is less, but the back-flow is aggravated near the small vane, especially when interacting with the tongue, and a large amount of gas is generated at the suction surface of the small vane. In addition, the efficiency of centrifugal pump without vane is higher than that of centrifugal pump with vane, which provides a basis for the structural optimization of centrifugal pump.

Hybrid LES/RANS Study of Turbulent Flow in a Linear Compressor Cascade With Moving Casing

2010 ◽  
Author(s):  
Domenico Borello ◽  
Giovanni Delibra ◽  
Kemal Hanjalic´ ◽  
Franco Rispoli
Keyword(s):  
Relative Motion ◽  
Flow Characteristics ◽  
Secondary Flows ◽  
Wall Region ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Tip Leakage ◽  
Rans Model ◽  
Turbulence Structures ◽  
Linear Compressor Cascade

In this work a robust hybrid LES/RANS model has been applied to the prediction of secondary flows in a linear compressor cascade with moving casing simulating the relative motion between blade and the casing. The hybrid LES/RANS model uses the well established Ζ-f URANS model of Hanjalic´ et al. (2004) in the near wall region coupled with dynamic Smagorinsky LES. The switch between the two zones is based on a couple of parameters defining the boundary of interface region: the first one is a grid-detection parameter expressed as a function of the ratio between the turbulent and LES characteristic length scales while the switching to pure LES is obtained when the subgrid scale viscosity is greater than eddy viscosity (Delibra et al., 2010). We present hybrid LES/RANS results of a 3D linear compressor cascade with a tip leakage equal to 1.65% of chord. We compare two cascade configurations: with stationary casing and with moving casing. The second simulation allows to scrutinize the exclusive influence of the relative motion between casing and blades on the tip leakage vortex and the turbulent structures developing in the wake. The quality of the results and their agreement with experiments are encouraging in terms of prediction of the main flow characteristics and identification of turbulence structures.

Understanding of Secondary Flows and Losses in Radial and Mixed Flow Turbines

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Bijie Yang ◽  
Peter Newton ◽  
Ricardo Martinez-Botas
Keyword(s):  
Secondary Flows ◽  
Limited Attention ◽  
Centrifugal Forces ◽  
Suction Surface ◽  
Flow Topology ◽  
Mixed Flow ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Surface Separation ◽  
Pressure Surface

Abstract Radial or mixed flow turbines are very common in industrial application, spanning turbochargers, small turbines for power generation, and energy recovery systems. Secondary flows have received a limited attention in the literature, and this papers aims to fill this gap of knowledge. The secondary flow structures in mixed flow turbines are particularly complex due to its geometry, high curvature, and the appearance of Coriolis and centrifugal forces. The focus of the present work is to investigate the evolution of secondary flows and their losses in a mixed flow turbine by using an experimentally validated three-dimensional computational fluid dynamics (CFD). The flow topology is analyzed to explain the formation and evolution of flow separations at the pressure, suction, and hub surfaces. The suction surface separation is caused by centrifugal forces, and it induces the formation of a hub separation. As the inlet velocity decreases, the hub separation increases in strength. A major feature found is the pressure surface separation, located at the leading edge tip, formed due to flow incidence; as the incidence decreases, this separation extends to the hub. Losses caused by those separations as well as the tip leakage vortex are studied by calculating locally entropy generation. Results show that the tip-leakage vortex accounts for the majority of losses (60%) and renders the losses caused by suction surface and induced hub separations to be small. The presence of the more severe hub separation was also found to have a significant detrimental effect on the turbine efficiency, which increases losses on the hub and the suction surface from 40% to 65%. Pressure surface separation, however, does not vary the total amount of losses significantly but rather redistributes the losses in the blade passage.

Tip Clearance Effects in a Turbine Rotor: Part II — Velocity Field and Flow Physics

2000 ◽  
Author(s):  
Andrew A. McCarter ◽  
Xinwen Xiao ◽  
Budugar Lakshminarayana
Keyword(s):  
Secondary Flow ◽  
Relative Motion ◽  
Turbine Rotor ◽  
Tip Clearance ◽  
Probe Laser ◽  
Laser Doppler Velocimeter ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Tip Leakage

A comprehensive experimental investigation was undertaken to explore the flow field in the tip clearance region of a turbine rotor to understand the physics of tip leakage flow. Specifically the paper looks at its origin, nature, development, interaction with the secondary flow, and its effects on performance. The experimental study was based on data obtained using a rotating five-hole probe, laser doppler velocimeter, high-response pressure probes on the casing, and static pressure taps on the rotor blade surfaces. The first part of the paper deals with the pressure field and losses. Part II presents and interprets the vorticity, velocity, and turbulence fields at several axial locations. The data provided here indicates that the tip leakage vortex originates in the last half chord. The leakage vortex is confined close to the suction surface corner near the blade tip by the relative motion of the blade and the casing, and by the secondary flow in the tip region. The tip leakage flow clings to the blade suction surface until midchord then lifts off of the suction surface to form a vortex in the last 20% of the blade chord. The relative motion between blades and casing leads to the development of a scraping vortex which, along with the secondary flow, reduces the propagation of the tip leakage flow into the mainflow. The rotational effects and corriolis forces modify the turbulence structure in the tip leakage flow and secondary flow as compared to cascades.

Flowfield Measurements in the Endwall Region of a Stator Vane

1999 ◽  
Vol 122 (3) ◽  
pp. 458-466 ◽  
Author(s):  
M. B. Kang ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Suction Side ◽  
Secondary Flows ◽  
Laser Doppler Velocimeter ◽  
Transfer Coefficients ◽  
Suction Surface ◽  
Numerical Predictions ◽  
High Heat Transfer ◽  
Passage Vortex ◽  
Stator Vane

A first-stage stator vane experiences high heat transfer rates, particularly near the endwall, where strong secondary flows occur. In order to improve numerical predictions of the complex endwall flow at low-speed conditions, benchmark quality experimental data are required. This study documents the flowfield in the endwall region of a stator vane that has been scaled up by a factor of nine while matching an engine exit Reynolds number of Reex=1.2×106. Laser Doppler velocimeter (LDV) measurements of all three components of the mean and fluctuating velocities are presented for several flow planes normal to the turbine vane. Measurements indicate that downstream of the minimum static pressure location on the suction surface of the vane, an attenuated suction side leg of the horseshoe vortex still exists. At this location, the peak turbulent kinetic energy coincides with the center of the passage vortex location. These flowfield measurements were also related to previously reported convective heat transfer coefficients on the endwall showing that high Stanton numbers occur where the passage vortex brings mainstream fluid toward the vane surface. [S0889-504X(00)00803-5]

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