scholarly journals Experimental Measurements of Rotordynamic Forces Caused by Front Shroud Pump Leakage

1999 ◽  
Vol 121 (3) ◽  
pp. 633-637 ◽  
Author(s):  
Robert V. Uy ◽  
Christopher E. Brennen
Keyword(s):  
Fluid Flow ◽  
Flow Coefficient ◽  
Leakage Flow ◽  
Experimental Measurements ◽  
Unsteady Forces ◽  
Leakage Path ◽  
Swirl Velocity ◽  
Inlet Swirl ◽  
Flow Through ◽  
Rotordynamic Forces

Unsteady forces generated by fluid flow through the impeller shroud leakage path of a centrifugal pump were investigated. Different pump shroud geometries were compared, and the effect of leakage path inlet swirl (pump discharge swirl) on the rotordynamic forces was examined for various ratios of fluid throughflow velocity to impeller tip speed. A short axial length leakage path reduced the measured forces, while curvature appeared to increase the destabilizing forces when inlet swirl was present. It was observed that changing the inlet swirl velocity does not appear to significantly affect the measured forces for a given leakage flow coefficient, but any nonzero inlet swirl is destabilizing when compared to cases with no inlet swirl.

scholarly journals Effect of Swirl on Rotordynamic Forces Caused by Front Shroud Pump Leakage

2002 ◽  
Vol 124 (4) ◽  
pp. 1005-1010 ◽  
Author(s):  
Yun Hsu ◽  
Christopher E. Brennen
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Leakage Flow ◽  
Unsteady Forces ◽  
Low Leakage ◽  
Leakage Path ◽  
Leakage Flow Rate ◽  
Inlet Swirl ◽  
Flow Through ◽  
Rotordynamic Forces

Unsteady forces generated by fluid flow through the impeller shroud leakage path of a centrifugal pump were investigated. The effect of leakage path inlet swirl (pump discharge swirl) on the rotordynamic forces was re-examined. It was observed that increasing the inlet swirl is destabilizing both for normal and tangential rotordynamic forces. Attempts to reduce the swirl within the leakage path using ribs and grooves as swirl brakes showed benefits only at low leakage flow rate.

Influence of Teeth Damage on Rotordynamic Instability of Impeller Eye Seals in Centrifugal Compressors

2005 ◽  
Author(s):  
Jinxiang Xi ◽  
David L. Rhode
Keyword(s):  
Labyrinth Seal ◽  
Accurate Prediction ◽  
Centrifugal Compressors ◽  
Perturbation Model ◽  
Rotordynamic Coefficients ◽  
Leakage Path ◽  
Swirl Velocity ◽  
Inlet Swirl ◽  
Rotordynamic Forces

This paper investigates the influence of labyrinth seal teeth damage due to rotor impacting on the performance and the rotordynamic characteristics of impeller eye seals in centrifugal compressors. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. The inclusion of at least an approximate shroud leakage path chamber is prefered for accurate prediction of seal-inlet swirl velocity and flow-induced rotordynamic forces. Impeller eye seals with teeth damage: (a) suffer significant leakage increases due to the increased seal clearance and (b) produce higher seal-inlet swirl velocity as well as larger rotordynamic forces, which tend to cause the system to become unstable. It was also found that distorted teeth tip geometries have an insignificant influence on both leakage and rotordynamic coefficients. The leakage path influence on seal-inlet swirl velocity W0 was also explored to thoroughly understand the rotordynamic characteristics of the eye seal subject to various degrees of teeth damage.

scholarly journals The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump

1992 ◽  
Author(s):  
A. Guinzburg ◽  
C. E. Brennen ◽  
A. J. Acosta ◽  
T. K. Caughey
Keyword(s):  
Centrifugal Pump ◽  
Guide Vane ◽  
Tangential Force ◽  
Inlet Guide Vane ◽  
Fluid Forces ◽  
Leakage Flows ◽  
Leakage Path ◽  
Inlet Swirl ◽  
Rotating Impeller ◽  
Rotordynamic Forces

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

scholarly journals Modeling of Cavitating Flow through Waterjet Propulsors

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Jules W. Lindau ◽  
Christopher Pena ◽  
Warren J. Baker ◽  
James J. Dreyer ◽  
William L. Moody ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Total Pressure ◽  
Axial Flow ◽  
Flow Coefficient ◽  
Experimental Measurements ◽  
Computational Results ◽  
Suction Surface ◽  
Blade Passage ◽  
Wide Range ◽  
Flow Through

A computational-fluid-dynamics-based modeling effort to capture flow through an axial flow waterjet propulsor is presented. The effort covered the waterjet flow over a wide range of flow coefficients and into cavitation-driven breakdown. The computations are presented in cavitation at two values of flow coefficient through a series of decreasing operating inlet total pressure. The computational results are compared to experimental measurements. Suction-surface and tip-gap cavitation patterns are presented and compared to experimental photographs. Presented computational solutions are blade-passage steady and periodic. The computational results apply a powering iteration methodology to facilitate coupling of rotor, stator, and inflow and outflow ducting.

scholarly journals Flow Development Through Inter-Turbine Diffusers

1996 ◽  
Author(s):  
Robert G. Dominy ◽  
David A. Kirkham ◽  
Andrew D. Smith
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Experimental Measurements ◽  
Good Prediction ◽  
Pressure Gradients ◽  
Computational Simulations ◽  
Flow Development ◽  
Inlet Swirl

Inter-turbine diffusers offer the potential advantage of reducing the flow coefficient in the following stages leading to increased efficiency. The flows associated with these ducts differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. Experimental data and numerical simulations clearly reveal the generation of significant secondary flows as the flow develops through the diffuser in the presence of cross-passage pressure gradients. The further influence of inlet swirl is also demonstrated. Data from experimental measurements with and without an upstream turbine are discussed and computational simulations are shown not only to give a good prediction of the flow development within the diffuser but also to demonstrate the importance of modelling the fully three-dimensional nature of the flow.

Flow Development Through Interturbine Diffusers

1998 ◽  
Vol 120 (2) ◽  
pp. 298-304 ◽  
Author(s):  
R. G. Dominy ◽  
D. A. Kirkham ◽  
A. D. Smith
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Experimental Measurements ◽  
Good Prediction ◽  
Pressure Gradients ◽  
Computational Simulations ◽  
Flow Development ◽  
Inlet Swirl

Interturbine diffusers offer the potential advantage of reducing the flow coefficient in the following stages, leading to increased efficiency. The flows associated with these ducts differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. Experimental data and numerical simulations clearly reveal the generation of significant secondary flows as the flow develops through the diffuser in the presence of cross-passage pressure gradients. The further influence of inlet swirl is also demonstrated. Data from experimental measurements with and without an upstream turbine are discussed and computational simulations are shown not only to give a good prediction of the flow development within the diffuser but also to demonstrate the importance of modeling the fully three-dimensional nature of the flow.

The decay of a turbulent swirl in a pipe

1965 ◽  
Vol 22 (2) ◽  
pp. 257-271 ◽  
Author(s):  
Frank Kreith ◽  
O. K. Sonju
Keyword(s):  
Experimental Data ◽  
Eddy Diffusivity ◽  
Reynolds Numbers ◽  
Experimental Measurements ◽  
Number Range ◽  
Swirl Velocity ◽  
Linearized Theory ◽  
Flow Through ◽  
Initial Intensity ◽  
Good Agreement

This paper presents a linearized theory for the average decay of a tape-induced fully developed turbulent swirl in flow through a pipe. In the Reynolds number range between 104 and 105 the theoretical analysis was found to be in good agreement with experimental data obtained with water in a 1 in. pipe, provided the eddy diffusivity was chosen appropriately.It was observed that a turbulent swirl decays to about 10–20% of its initial intensity in a distance of about 50 pipe diameters, the decay being more rapid at smaller than at larger Reynolds numbers. The theoretical swirl velocity distribution agreed qualitatively with experimental measurements at distances less than 20 diameters downstream from the outlet of the swirl inducer, but deviated from the experimental results further downstream.

scholarly journals The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump

1993 ◽  
Vol 115 (2) ◽  
pp. 287-293 ◽  
Author(s):  
A. Guinzburg ◽  
C. E. Brennen ◽  
A. J. Acosta ◽  
T. K. Caughey
Keyword(s):  
Centrifugal Pump ◽  
Guide Vane ◽  
Tangential Force ◽  
Inlet Guide Vane ◽  
Fluid Forces ◽  
Leakage Flows ◽  
Leakage Path ◽  
Inlet Swirl ◽  
Rotating Impeller ◽  
Rotordynamic Forces

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrate substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

Labyrinth-Seal Leakage Analysis

1959 ◽  
Vol 81 (3) ◽  
pp. 332-336 ◽  
Author(s):  
W. Zabriskie ◽  
B. Sternlicht
Keyword(s):  
Fluid Flow ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Steam Turbines ◽  
Labyrinth Seals ◽  
Gas Leakage ◽  
Leakage Flows ◽  
Seal Design ◽  
Flow Through ◽  
The Subject

The leakage flow through labyrinth seals in turbomachinery has been the subject of increasing concern as refinements and advances in design are made. Accurate knowledge of seal leakage is necessary in at least three areas of design: (a) Estimating the effect of seal leakage on performance; (b) regulating the leakage flow required for cooling purposes; (c) determining the thrust-bearing load which is a function of the pressure drop through the seal. This paper is concerned primarily with the fluid-flow aspect of gas leakage through labyrinth seals of the types commonly used in gas and steam turbines. This includes staggered and unstaggered seals of the axial type, which are most commonly used in turbomachinery. The attention to fluid-flow considerations does not imply that material compatibility and operating problems of expansion, deformation, and rub-in are unimportant. In fact, these mechanical considerations may overrule the fluid-flow considerations. For the foregoing reasons, it is desirable to be able to predict seal leakage flows, and thus this aspect of seal design has been singled out for consideration here.

scholarly journals Experimental Investigations on Leakages in Positive Displacement Machines

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Hitesh H. Patel ◽  
Vikas J. Lakhera
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Pressure Ratio ◽  
Flow Coefficient ◽  
Experimental Investigations ◽  
Mean Deviation ◽  
Leakage Flow ◽  
Positive Displacement ◽  
Flow Through ◽  
The Mean

The clearance gaps in positive displacement machines such as compressors, pumps, expanders, and turbines are critical for their performance and reliability. The leakage flow through these clearances influences the volumetric and adiabatic efficiencies of the machines. The extent of the leakage flow depends on the size and shape of clearance paths and pressure differences across these paths. Usually, the mass flow through the gaps is estimated using the isentropic nozzle equation with the flow coefficients applied to correct for the real flow conditions. However, the flow coefficients applied generally do not take into account the shape and size of these leakage paths. For that reason, a proper understanding of the relationship between flow coefficients and shape parameters is crucial for an accurate prediction of leakage flows. The present study investigates the influence of the various dimensionless parameters such as Reynolds number, Mach number, and pressure ratio on the flow coefficients for circular and rectangular clearance shapes. The flow coefficients are determined by comparing the experimental values obtained in an experimental test rig and the flow rates obtained from the isentropic nozzle equation. It is observed that in the case of circular clearances, the mean deviation of the experimental leakage results (in comparison to the analytical results using isotropic nozzle equations) is +9.1%, which is significantly lower than the mean deviation (+20.5%) in the case of rectangular clearance leakages. The study indicates that the isentropic nozzle equation method is more suitable for predicting the leakages through the circular clearances and needs modifications for consideration of the rectangular clearances. Using regression analysis, empirical correlations are developed to predict the flow coefficient in terms of Reynolds number, Mach number, pressure ratio, aspect ratio, and β ratio, which are found to match within ±6.4 percent of the numerical results for the rectangular clearance and within the range of -3.6 percent to +5.1 percent of the numerical result for the circular clearance. The empirical relationships presented in this study can be extended to evaluate the flow coefficients in a positive displacement machine.

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