Off-Design Flow Measurements in a Centrifugal Compressor Vaneless Diffuser

1995 ◽  
Vol 117 (4) ◽  
pp. 602-608 ◽  
Author(s):  
A. Pinarbasi ◽  
M. W. Johnson
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Secondary Flows ◽  
Design Flow ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Flow Rates ◽  
Study Results

Detailed measurements have been taken of the three-dimensional velocity field within the vaneless diffuser of a backswept low speed centrifugal compressor using hot-wire anemometry. A 16 percent below and an 11 percent above design flow rate were used in the present study. Results at both flow rates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flow rate delay the mixing out of the circumferential velocity variations, but at both flow rates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flow angle is used to recommend optimum values for the vaneless space and vane angle for design of a vaned diffuser.

scholarly journals Off Design Flow Measurements in a Centrifugal Compressor Vaneless Diffuser

1994 ◽  
Author(s):  
Ali Pinarbasi ◽  
Mark W. Johnson
Keyword(s):  
Velocity Field ◽  
Centrifugal Compressor ◽  
Secondary Flows ◽  
Design Flow ◽  
Circumferential Velocity ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Vaned Diffuser ◽  
Study Results ◽  
Vane Angle

Detailed measurements have been taken of the 3-d velocity field within the vaneless diffuser af a backswept law speed centrifugal compressor using hat wire anemometry. A 16% below and an 11% above design flowrate were used in the present study. Results at both flowrates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flowrate delay the mixing out of the circumferential velocity variations, but at both flowrates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flaw angle is used to recommend optimum values far the vaneless space and vane angle for design of a vaned diffuser.

scholarly journals Detailed Off Design Flow Measurements in a Centrifugal Compressor Vaned Diffuser

1997 ◽  
Author(s):  
Ali Pinarbasi ◽  
Mark W. Johnson
Keyword(s):  
Centrifugal Compressor ◽  
Flow Characteristic ◽  
Design Flow ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Hot Wire ◽  
Vaneless Diffuser ◽  
Mean Velocity ◽  
Flow Measurements ◽  
Vaned Diffuser

Three component hot wire measurements in the vaneless space and vane region of a low speed centrifugal compressor vaned diffuser are presented. These comprise mean velocity and turbulence level distributions for a below and above design flow rate for three vane-to-vane locations at each of five radial measurement stations. The flow entering the diffuser closely resembles the classic jet-wake flow characteristic of centrifugal impeller discharges. A strong upstream influence of the diffuser vanes is observed which results in significant variations in flow quantities between the vane-to-vane locations. The circumferential variations due to the passage and blade wakes rapidly mix out in the vaneless space, although some variations are still discernible in the vaned region. Comparison with results in a vaneless diffuser suggest that the presence of the vanes accelerates this mixing out process.

Design and Off-Design Numerical Investigation of a Transonic Double-Splitter Centrifugal Compressor

2008 ◽  
Author(s):  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Seiichi Ibaraki
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Cross Sections ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Complex Flow ◽  
Flow Measurements ◽  
Vaned Diffuser

The flow field of a high pressure ratio centrifugal compressor for turbocharger applications is investigated using a three-dimensional Navier-Stokes solver. The compressor is composed of a double-splitter impeller followed by a vaned diffuser. The flow field of the transonic open-shrouded impeller is highly three-dimensional, and it is influenced by shock waves, tip leakage vortices and secondary flows. Their interactions generate complex flow structures which are convected and distorted through the impeller blades. Both steady and unsteady computations are performed in order to understand the physical mechanisms which govern the impeller flow field while the operation ranges from choke to surge. Detailed Laser Doppler Velocimetry (LDV) flow measurements are available at various cross-sections inside the impeller blades at both design and off-design operating conditions.

Secondary Flows in Centrifugal Pump Impellers: PIV Measurements and CFD Computations

2009 ◽  
Author(s):  
R. W. Westra ◽  
L. Broersma ◽  
K. van Andel ◽  
N. P. Kruyt
Keyword(s):  
Reynolds Number ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Stokes Equations ◽  
Suction Side ◽  
Velocity Profiles ◽  
Secondary Flows ◽  
Design Flow ◽  
Low Velocity ◽  
Flow Rates

Two-dimensional Particle Image Velocimetry measurements and three-dimensional Computational Fluid Dynamics (CFD) analyses have been performed of the flow field inside the impeller of a low specific-speed centrifugal pump operating with a vaneless diffuser. Flow rates ranging from 80% to 120% of the design flow rate are considered in detail. It is observed from the velocity measurements that secondary flows occur. These flows result in the formation of regions of low velocity near the intersection of blade suction side and shroud. The extent of this jet-wake structure decreases with increasing flow rate. Velocity profiles have also been computed from Reynolds-averaged Navier-Stokes equations with the Spalart-Allmaras turbulence model, using a commercial CFD-code. For the considered flow rates the qualitative agreement between measured and computed velocity profiles is very good. Overall, the average relative difference between these velocity profiles is around 7%. Additional CFD computations have been performed to assess the influence of Reynolds number and shape of the inlet velocity profile on the computed velocity profiles. It is found that the influence of Reynolds number is mild. The shape of the inlet profile only has a weak effect at the shroud.

Numerical and Experimental Analysis of the Flow in a Centrifugal Pump at Nominal and Partial Flow Rate

1992 ◽  
Author(s):  
J. F. Combes ◽  
E. Rieutord
Keyword(s):  
Turbulent Flow ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Suction Side ◽  
Design Flow ◽  
Low Flow ◽  
Laser Doppler Velocimeter ◽  
Finite Element Code ◽  
Flow Measurements ◽  
Flow Rates

Detailed flow measurements in the impeller and the diffuser of an industrial centrifugal pump have been performed with a 2-component laser Doppler velocimeter. Measurements were made at 8 radial positions for flow rates ranging from 50% to 100% of design flow. The experimental results were compared to 3D turbulent flow calculations performed with a finite element code. At nominal flow rate, both measurements and calculations show a wake pattern along the suction side at the shroud. The flow is separated in the diffuser on the hub, and on the shroud at low flow rate. The inlet recirculation, occurring at 0.65 Qn is well predicted by the turbulent flow calculation.

scholarly journals Experimental Flow Field Investigation in a Centrifugal Compressor Vaned Diffuser

1995 ◽  
Author(s):  
Ali Pinarbasi ◽  
Mark W. Johnson
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Centrifugal Compressor ◽  
Field Investigation ◽  
Vaneless Diffuser ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Impeller Blade ◽  
Vaned Diffuser ◽  
Flow Angle

The purpose of this study was to improve the understanding of the flow physics in a centrifugal compressor vaned diffuser. A low speed compressor with a 19 bladed backswept impeller and diffuser with 16 wedge vanes was used. The measurements were made at three inter-vane positions and are presented as mean velocity, turbulent kinetic energy and flow angle distributions on eight diffuser cross sectional planes. The impeller blade wakes mix out rapidly within the vaneless space and more rapidly than in an equivalent vaneless diffuser. Although the flow is highly non uniform in velocity at the impeller exit, there is no evidence in the results of any separation from the diffuser vanes. The results do however suggest that the use of twisted vanes within the diffuser would be beneficial in reducing losses.

Radial Forces in a Centrifugal Compressor Equipped With Vaned Diffusers

2009 ◽  
Author(s):  
Ahti Jaatinen ◽  
Jari L. H. Backman ◽  
Teemu Turunen-Saaresti
Keyword(s):  
Centrifugal Compressor ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Design Flow ◽  
Vaneless Diffuser ◽  
Rotating Shaft ◽  
Vaned Diffuser ◽  
Pressure Distributions ◽  
Impeller Outlet ◽  
Radial Forces

A non-uniform pressure distribution in a volute of a centrifugal compressor causes a radial force on the impeller and the rotating shaft. The diffuser preceding the volute determines how the flow field entering to the volute, and affects the radial forces that are caused by the volute towards the impeller. The radial forces were measured for three different vaned diffuser geometries and one vaneless diffuser with a pinch. The force measurements were made for each assembly with the same compressor using active magnetic bearings. The impeller forces were found to be the smallest near the design flow and higher at choke and at stall for all configurations. The radial forces on the impeller were higher with the vaneless diffuser than with the vaned diffuser. The force distributions with the vaned diffusers were uniform and clearly different from those of the vaneless diffuser. In addition, the radial forces were estimated using static pressure distributions measured at the impeller outlet. The radial force determined from the pressure measurements verified the measured forces obtained in the magnetic bearing measurements.

Slip Factor of a Centrifugal Compressor and Its Variation with Flow Rate

1974 ◽  
Vol 188 (1) ◽  
pp. 415-421 ◽  
Author(s):  
A. Whitfield
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Flow Model ◽  
Design Flow ◽  
Wake Flow ◽  
Flow Rates ◽  
One Dimensional ◽  
Slip Factor ◽  
Performance Map ◽  
The Many

To predict the complete performance map of turbocharger centrifugal compressors, it has been found essential to include a procedure for estimating the slip factor at off-design flow rates. The many correlations available for the slip factor only concern themselves with design-point operation and consequently only provide a single value for the slip factor. The approach presented here attempts, within the confines of a one-dimensional procedure, to recognize the changing flow pattern at the impeller discharge in order to predict the variation of slip factor with flow rate. The procedure is based upon the well-established jet-wake flow model of Dean and the overall slip factor calculated from the jet slip factor. Experimental and theoretical slip factors are presented for three impellers with 34, 30 and 12 radial blades, respectively. The complete performance map of the 12-bladed turbocharger compressor and the effect of using a constant and varying slip factor on the predicted performance are presented.

Sign in / Sign up

Export Citation Format

Share Document