Experimental and Theoretical Study of the Swirling Flow in Centrifugal Compressor Volutes

1990 ◽  
Vol 112 (1) ◽  
pp. 38-43 ◽  
Author(s):  
R. A. Van den Braembussche ◽  
B. M. Ha¨nde
Keyword(s):  
Centrifugal Compressor ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Three Dimensional Flow ◽  
Static Pressure Distribution ◽  
Swirl Velocity ◽  
Isentropic Flows ◽  
Operating Points

Measurements of the three-dimensional flow in a simplified model of a centrifugal compressor volute at design and off-design operation are presented. A nearly constant swirl velocity is observed near the walls and a forced vortex type of flow is observed in the center. This velocity distribution is almost identical at all cross sections and all operating points. An explanation is given on how this swirl distribution results from the specific way a volute is filled with fluid. The throughflow velocity component shows a large crosswise variation. A minimum or maximum velocity is observed at the volute center depending on the operating point. A simple analytic model, based on the radial equilibrium of forces, is described. Calculations for isentropic flows reveal the relation between the swirl distribution and the large increase of throughflow velocity toward the center. This explains why volutes should be designed with negative blockage. Nonisentropic calculations, using the experimental loss distribution, correctly reproduce the measured throughflow velocity and static pressure distribution.

Experimental and Theoretical Analysis of the Flow in a Centrifugal Compressor Volute

1993 ◽  
Vol 115 (3) ◽  
pp. 582-589 ◽  
Author(s):  
E. Ayder ◽  
R. Van den Braembussche ◽  
J. J. Brasz
Keyword(s):  
Centrifugal Compressor ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Elliptical Cross ◽  
Loss Model ◽  
Tangential Flow ◽  
Static Pressure Distribution ◽  
Flow Loss ◽  
Mean Streamline Analysis

Detailed measurements of the swirling flow in a centrifugal compressor volute with elliptical cross section are presented. They show important variations of the swirl and throughflow velocity, total and static pressure distribution at the different volute cross sections and at the diffuser exit. The basic mechanisms defining the complex three dimensional flow structure are clarified. The different sources of pressure loss have been investigated and used to improve the prediction capability of one-dimensional mean streamline analysis correlations. The tangential flow loss model under decelerating flow conditions and the friction loss model are confirmed. New empirical loss coefficients are proposed for the exit cone loss model and the tangential flow loss model for the case of accelerating flow in the volute.

scholarly journals Experimental and Theoretical Study of the Swirling Flow in Centrifugal Compressor Volutes

1989 ◽  
Author(s):  
R. A. Van Den Braembussche ◽  
B. M. Hände
Keyword(s):  
Centrifugal Compressor ◽  
Theoretical Study ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Simplified Model ◽  
Three Dimensional Flow ◽  
Dimensional Flow

Measurements of the three-dimensional flow in a simplified model of a centrifugal compressor volute at design and off-design operation are presented.

Experimental and Theoretical Analysis of the Flow in a Centrifugal Compressor Volute

1992 ◽  
Author(s):  
E. Ayder ◽  
R. Van den Braembussche ◽  
J. J. Brasz
Keyword(s):  
Centrifugal Compressor ◽  
Cross Sections ◽  
Swirling Flow ◽  
Elliptical Cross ◽  
Loss Model ◽  
Pressure Losses ◽  
Tangential Flow ◽  
Static Pressure Distribution ◽  
Flow Loss ◽  
Mean Streamline Analysis

Detailed measurements of the swirling flow in a centrifugal compressor volute with elliptical cross section are presented. They show important variations of the swirl- and throughflow velocity, total and static pressure distribution at the different volute cross sections and at the diffuser exit. The basic mechanisms defining the complex 3D flow structure are clarified. The different sources of pressure losses have been investigated and used to improve the prediction capability of one dimensional mean streamline analysis correlations. The tangential flow loss model, under decelerating flow conditions, and friction loss model are confirmed. New emprical loss coefficients are proposed for the exit cone loss model and the tangential flow loss model for the case of accelerating flow in the volute.

Experimental Study of the Swirling Flow in the Volute of a Centrifugal Pump

1992 ◽  
Vol 114 (2) ◽  
pp. 366-372 ◽  
Author(s):  
T. Elholm ◽  
E. Ayder ◽  
R. Van den Braembussche
Keyword(s):  
Velocity Distribution ◽  
Mass Flow ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
High Mass ◽  
Return Flow ◽  
Swirl Velocity ◽  
Low Mass

Detailed three-dimensional velocity distributions, corresponding to design and off-design operation, were measured in two different circumferential cross sections of a volute by means of LDV. It is shown that the swirl has a forced vortex type velocity distribution and that the location of the swirl center changes with mass flow. The throughflow velocity distribution is primarily defined by the conservation of angular momentum. A strong interaction between the throughflow and swirl velocity is observed. Flow visualization in the tongue region reveals a reversal of the velocity at the volute inlet with increasing mass flow. The pressure drop between volute outlet and inlet at low mass flow pushes extra fluid through the tongue gap and increases the mass flow in the volute. The abrupt pressure rise at high mass flow results in local return flow perturbing the flow in the outlet pipe.

Analytical Theory of Three Dimensional Flow in Centrifugal Compressors

1981 ◽  
Vol 23 (4) ◽  
pp. 179-191 ◽  
Author(s):  
C. Bosman
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Surface Flow ◽  
Centrifugal Compressors ◽  
Three Dimensional Flow ◽  
Stream Tube ◽  
Stream Surface ◽  
Dimensional Flow ◽  
Passage Vortex ◽  
Turbomachine Blade

Inviscid, compressible flow along a rotating elemental stream-tube is taken as a model for flow through a turbomachine blade passage. For this model an analytic expression for the relative secondary vorticity of the flow is derived which permits the mean stream-surface twist about the tube axis to be evaluated. This twist implies a migration of the fluid particles from one tube corner to the contiguous tube corner, a flow feature suppressed by all existing stream-sheet flow calculations in turbomachine blade rows. The analysis is applied to a centrifugal compressor configuration where the effects on the secondary flow of hub/shroud geometry, blade shape, compressibility, and meridional diffusion are investigated. The stream-surface twist, not being primarily dependent upon the elemental nature of the stream-tube is taken as a measure of stream-surface twist and consequent surface flow migration in finite blade passages. The levels of twist obtained from the analysis are similar to those obtained in three dimensional flow calculations using primitive variables as illustrated by Bosman (1) (2)‡ and show that existing streamsheet and streamsheet stacking methods, all of which suppress the relative passage vortex are an inadequate model of the flow in centrifugal compressors. The analysis clearly shows that contrary to common assumption, centrifugal compressor impellers are capable of generating a passage vortex in the same direction as that of blade rotation.

scholarly journals The Theory and Observational Evidence for Streamlets: A New Velocity-Based Feature Model of Jet Streams and Eddies in the Oceans

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Alexander V. Kazansky ◽  
Antonina A. Shupikova
Keyword(s):  
Cross Sections ◽  
Velocity Structure ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Feature Model ◽  
Optimal Interpolation ◽  
Jet Streams ◽  
Synoptic Features ◽  
Parametric Functions ◽  
Oblique Cone

The aim of this study is the verification of a new velocity-based feature model, called streamlets, proposed recently for objective analysis of the three-dimensional velocity structure of jet streams and eddies in the oceans. Streamlets are continuously imbedded shearing vortex solenoids having two forms: cylindrical (for jets) or toroidal (for eddies, considered as self-closed jets). Both these forms comprise stream coordinates based on streamlines of maximum velocity as an axis and vertical velocity cross-sections defined as an oblique cone with elliptical base. Assimilation of velocity measurements is accomplished by fitting this cone to available data using the well-known Nelder-Mead simplex downhill algorithm for finding the minimum of nonlinear parametric functions. Advantages of the streamlet model are discussed emphasizing its functional integrity. The focus is on velocity data assimilation based on coherency of synoptic scale features as opposed to usual pointwise assimilation methods such as averaging or optimal interpolation. Case studies present synoptic features of a different origin and scale including surface-intensified and subsurface baroclinic examples as well as deep barotropic ones demonstrating universality of the model. The theory of streamlets is also addressed in this paper, since it further sustain the streamlet model.

A Photographic Study of the Three-Dimensional Flow in a Radial Compressor

1968 ◽  
Vol 90 (3) ◽  
pp. 237-243 ◽  
Author(s):  
Y. Senoo ◽  
M. Yamaguchi ◽  
M. Nishi
Keyword(s):  
Secondary Flow ◽  
Centrifugal Compressor ◽  
Turbulent Mixing ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Working Fluid ◽  
Vaneless Diffuser ◽  
Three Dimensional Flow ◽  
Radial Compressor ◽  
Dimensional Flow

In order to visualize the three-dimensional flow in the impeller and the vaneless diffuser of a centrifugal compressor, water is used as the working fluid and streak lines of colored water are photographed and examined. The test is made at an extremely low speed so that streak lines do not diffuse due to turbulent mixing. The streak lines clearly demonstrate several types of secondary flow, some of which agree with what have been speculated to exist in actual compressors. Most of observed secondary flow patterns are qualitatively understandable with existing theories.

Effects of volute’s asymmetry on the performance of a turbocharger centrifugal compressor

2016 ◽  
Vol 232 (7) ◽  
pp. 1235-1246 ◽  
Author(s):  
Xinqian Zheng ◽  
Yun Lin ◽  
Zhenzhong Sun
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Pressure Condition ◽  
Three Dimensional Flow ◽  
Outlet Pressure ◽  
Flow Mechanisms ◽  
Simulation Results ◽  
Steady Simulation ◽  
Stable Flow ◽  
Stage Efficiency

The effects of the volute’s asymmetry on the performance of a turbocharger centrifugal compressor were studied using steady simulations and theoretical analysis. According to the steady simulation results, it is found that the volute’s asymmetry has significant influence on the performance of the centrifugal compressor. The variation of the stage efficiency due to volute’s asymmetry is up to 4%. Meanwhile, the volute’s asymmetry restricts the compressor stable flow range by imposing a distorted outlet pressure condition and forcing some certain impeller passages to suffer from a worse flow than the others. These certain passages are likely to stall first and trigger the surge, as the stage flow rate further decreases. In other words, the local stall triggers the surge. The relevant flow mechanisms were given to explain the effects based on the three-dimensional flow field, and a new model was developed to demonstrate how the local stall induced by the volute’s asymmetry triggers the system instability.

Experimental Study of the Swirling Flow in the Volute of a Centrifugal Pump

1990 ◽  
Author(s):  
T. Elholm ◽  
E. Ayder ◽  
R. Van Den Braembussche
Keyword(s):  
Velocity Distribution ◽  
Mass Flow ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
High Mass ◽  
Return Flow ◽  
Flow Visualisation ◽  
Through Flow

The detailed three-dimensional velocity distributions, corresponding to design and off-design operation, were measured in two different circumferential cross sections of a volute by means of LDV. It is shown that the swirl has a forced vortex type velocity distribution and that the location of the swirl center is changing with mass flow. The through flow velocity distribution is primarily defined by the conservation of angular momentum. A strong interaction between the through flow and swirl velocity is observed. Flow visualisation in the tongue region reveals a reversal of the velocity at the volute inlet with increasing mass flow. The pressure drop between volute outlet and inlet at low mass flow pushes extra fluid through the tongue gap and increases the mass flow in the volute. The abrupt pressure rise at high mass flow results in local return flow perturbing the flow in the outlet pipe.

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