A Centrifugal Compressor Flow Analysis Employing a Jet-Wake Passage Flow Model

1977 ◽  
Vol 99 (1) ◽  
pp. 141-147 ◽  
Author(s):  
J. H. G. Howard ◽  
C. Osborne
Keyword(s):  
Centrifugal Compressor ◽  
Curve Fitting ◽  
Flow Model ◽  
Flow Analysis ◽  
Stagnation Pressure ◽  
Centrifugal Impeller ◽  
Experimental Measurements ◽  
Suction Surface ◽  
Streamline Curvature ◽  
Through Flow

The streamline curvature through-flow analysis of a centrifugal impeller passage flow has been modified to include a flow model with a wake on the suction surface. With this model, empirically determined or measured impeller conditions can be matched without requiring a distributed stagnation pressure loss within the passage. Its use in impeller design is presented and comparison with experimental measurements from two impellers illustrate the utility of this approach. A brief discussion of experience with the associated forms of curve fitting and streamline smoothing required for the analysis solution is included.

scholarly journals The Influence of Flow Rate on the Wake in a Centrifugal Impeller

1982 ◽  
Author(s):  
M. W. Johnson ◽  
J. Moore
Keyword(s):  
Flow Rate ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Centrifugal Impeller ◽  
Suction Surface ◽  
Cross Sectional ◽  
Flow Rates ◽  
Pressure Losses ◽  
Compressor Impeller

Three-dimensional flows and their influence on the stagnation pressure losses in a centrifugal compressor impeller have been studied. All 3 mutally perpendicular components of relative velocity and stagnation pressure on 5 cross-sectional planes, between the inlet and outlet of a 1 m dia shrouded impeller running at 500 rpm were measured. Comparisons were made between results for a flow rate corresponding to nearly zero incidence angle and two other flows, with increased and reduced flow rates. These detailed measurements show how the position of separation of the shroud boundary layer moved downstream and the wake’s size decreased, as the flow rate was increased. The wake’s location, at the outlet of the impeller, was also observed to move from the suction surface at the lowest flow rate, to the shroud at higher flow rates.

Influence of Swirl Distribution on Blade Shape and Performance of a Centrifugal Impeller

2020 ◽  
Author(s):  
Qin Cui ◽  
Guoliang Qin ◽  
Lei Li ◽  
Cheng Jia ◽  
Yi Wang
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Flow Direction ◽  
Input Parameter ◽  
Vortex Method ◽  
Centrifugal Impeller ◽  
Streamline Curvature ◽  
Design Program ◽  
Blade Shape ◽  
And Performance

Abstract All-over-controlled vortex method is an effective tool to inversely design the 3D impeller of a centrifugal compressor. In this method, swirl distribution is treated as a significant input parameter to control the blade shape, impeller flow field, and compressor performance. It is acknowledged that swirl distribution is prescribed by designers mostly relying on the personal experience at the beginning of design. So how to specify the swirl distribution is still a big challenge for impeller designers. Of the most interest in this paper is to provide a theoretical technique that can be readily applied to specify swirl distribution and reduce the dependence on the designers experience. A judgement criterion rCθ – ωr2 is proposed to design the swirl distribution. Based on the streamline curvature method, a 3D centrifugal impeller design program is developed to design centrifugal impeller. The scale and uniformity of rCθ – ωr2 along flow direction are discussed theoretically to conduct the specifying of swirl distribution. The theoretical analysis is verified by a specific centrifugal compressor case. Then commercial CFD software is used to predict the flow field and the performance of the impeller. The results demonstrate that the scale and distribution uniformity of rCθ – ωr2 have a significant effect on the blade shape and the flow field within the impeller, and possible loss can be reduced. For the new designer, it is possible to preliminarily recognize and eliminate the infeasible swirl distribution, and adjust the unsatisfactory swirl distribution using rCθ – ωr2. Proper blade shape and good impeller performance can be achieved with the help of the judgement criterion rCθ – ωr2.

Preliminary Study of a Centrifugal Compressor With Counter-Rotating Impellers: Design and Performances Study

2020 ◽  
Author(s):  
Abed Cheikh Brahim ◽  
Khelladi Sofiane ◽  
Deligant Michael ◽  
El Marjani Abdel ◽  
Farid Bakir
Keyword(s):  
Centrifugal Compressor ◽  
Degrees Of Freedom ◽  
Numerical Data ◽  
Centrifugal Impeller ◽  
Through Flow ◽  
Aerodynamic Performances ◽  
Preliminary Study ◽  
And Performance ◽  
And Control ◽  
Selection Of

Abstract Turbomachinery with double counter-rotating impellers offer more degrees of freedom in the choice of design and control parameters compared to conventional machines. For these innovative machines, the literature review shows that more published works are available concerning axial type turbomachines than centrifugal ones. This work deals with a preliminary design and performance analysis applied to two counter-rotating impellers of a centrifugal compressor. We present here the design practice developed based on 0D/1D models, also coupled with optimization and stream-curvature through-flow methods to satisfy the selected design-criteria. An analyze of aerodynamic performances results are made and compared to those available experimental and numerical data of a baseline configuration, composed of one centrifugal-impeller and a volute. The compressor studied here includes a first conventional impeller with an axial inlet and a mixed or centrifugal outlet. The second impeller is designed parametrically and can be considered as a rotating-diffuser with a radial or mixed inlet and outlet. Ultimately, the numerical simulation results of a selection of candidate solutions are discussed.

An Iterative Method for Blade Profile Loss Model Adaptation Using Streamline Curvature

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Vassilios Pachidis ◽  
Pericles Pilidis ◽  
Ioannis Templalexis ◽  
Luca Marinai
Keyword(s):  
Experimental Data ◽  
Flow Analysis ◽  
Public Domain ◽  
Model Adaptation ◽  
Blade Profile ◽  
Loss Model ◽  
Streamline Curvature ◽  
Through Flow ◽  
Loss Models ◽  
Profile Loss

The various incidence, deviation, and loss models used in through-flow analysis methods, such as streamline curvature, are nothing more than statistical curve fits. A closer look at public domain data reveals that these statistical correlations and curve fits are usually based on experimental cascade data that actually display a fairly large scatter, resulting in a relatively high degree of uncertainty. This usually leads to substantial differences between the calculated and actual performances of a given gas turbine engine component. Typically, matching calculated results from a through-flow analysis against experimental data requires the combination of various correlations available in the public domain, through a very tedious, complex, and time consuming “trial and error” process. This particular study supports the view that it might actually be much more time effective to “adopt” a given loss model against experimental data through an iterative, physics-based approach, rather than try to identify the best combination of available correlations. For example, the well-established “Swan’s model” for calculating the blade profile loss factor in subsonic and transonic axial flow compressors depends strongly on approximate correlations for calculating the blade wake momentum thickness, and therefore represents such a case. This study demonstrates this by looking into an iterative approach to blade profile loss model adaptation that can provide a relatively simple and quick, but also physics-based way of “calibrating” profile loss models against available experimental data for subsonic applications. This paper presents in detail all the analysis necessary to support the above concept and discusses Swan’s model in particular as an example. Finally, the paper discusses the performance comparison of a two-dimensional, streamline curvature compressor model against experimental data before and after the adaptation of that particular loss model. This analysis proves the potential of the simulation strategy presented in this paper to “adopt” a given loss model against experimental data through an iterative, physics-based approach.

scholarly journals Laser Anemometer Measurements of the Flow Field in a 4:1 Pressure Ratio Centrifugal Impeller

1997 ◽  
Author(s):  
G. J. Skoch ◽  
P. S. Prahst ◽  
M. P. Wernet ◽  
J. R. Wood ◽  
A. J. Strazisar
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Vaneless Diffuser ◽  
Suction Surface ◽  
Tip Clearance Flow ◽  
Through Flow ◽  
Clearance Flow ◽  
Flow Velocities

A laser-doppler anemometer was used to obtain flow-field velocity measurements in a 4:1 pressure ratio, 4.54 kg/s (10 lbm/s), centrifugal impeller, with splitter blades and backsweep, which was configured with a vaneless diffuser. Measured through-flow velocities are reported for ten quasi-orthogonal survey planes at locations ranging from 1% to 99% of main blade chord. Measured through-flow velocities are compared to those predicted by a 3-D viscous steady flow analysis (Dawes) code. The measurements show the development and progression through the impeller and vaneless diffuser of a through-flow velocity deficit which results from the tip clearance flow and accumulation of low momentum fluid centrifuged from the blade and hub surfaces. Flow traces from the CFD analysis show the origin of this deficit which begins to grow in the inlet region of the impeller where it is first detected near the suction surface side of the passage. It then moves toward the pressure side of the channel, due to the movement of tip clearance flow across the impeller passage, where it is cut by the splitter blade leading edge. As blade loading increases toward the rear of the channel the deficit region is driven back toward the suction surface by the cross-passage pressure gradient. There is no evidence of a large wake region that might result from flow separation and the impeller efficiency is relatively high. The flow field in this impeller is quite similar to that documented previously by NASA Lewis in a large low-speed backswept impeller.

The Uniqueness of Turbomachinery Flow Calculations Using the Streamline Curvature and Matrix Through-Flow Methods

1971 ◽  
Vol 13 (6) ◽  
pp. 376-379 ◽  
Author(s):  
H. Marsh
Keyword(s):  
Mach Number ◽  
Flow Pattern ◽  
Iterative Procedure ◽  
Flow Analysis ◽  
Alternative Procedure ◽  
Streamline Curvature ◽  
Through Flow ◽  
The Matrix ◽  
Uniqueness Of The Solution ◽  
Flow Through

When calculating the flow through turbomachines by an iterative procedure, it is assumed that on each cycle of iteration there is only one solution for the flow pattern. The uniqueness of the solution obtained by the method of streamline curvature is examined and a set of Mach number conditions are derived which are sufficient to ensure that the flow pattern is unique. The Mach number limitations are the same as those which are necessary to avoid ambiguity in the matrix through-flow analysis. An alternative procedure is then described in which the solution for the flow pattern is always unique.

Flow in Centrifugal Compressor Impellers: A Hub-to-Shroud Solution

1980 ◽  
Vol 22 (1) ◽  
pp. 1-8 ◽  
Author(s):  
A. Goulas ◽  
R. C. Baker
Keyword(s):  
Velocity Field ◽  
Centrifugal Compressor ◽  
Initial Velocity ◽  
Flow Analysis ◽  
Equation Of Motion ◽  
Stream Surface ◽  
Isentropic Flow ◽  
Through Flow ◽  
The Matrix ◽  
Compressor Impeller

The matrix through-flow analysis is applied to the hub-to-shroud stream surface of a centrifugal compressor impeller. The k-ε turbulence model is used to calculate the stress tensor necessary to obtain a dissipation force. Integration of the streamwise equation of motion yields an entropy field in agreement with the dissipation force. The results are compared with isentropic flow solutions. Furthermore, the effect on the velocity field of the initial velocity profiles and turbulence levels at the eye of the impeller are studied, as is the influence of the shroud on the flow.

A Blade-to-Blade Solution of the Flow in a Centrifugal Compressor Impeller with Splitters

1980 ◽  
Vol 102 (3) ◽  
pp. 632-637 ◽  
Author(s):  
A. Goulas
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Flow Analysis ◽  
Leading Edge ◽  
Suction Side ◽  
Stagnation Points ◽  
Axial Part ◽  
Through Flow ◽  
The Matrix ◽  
Compressor Impeller

The matrix through flow analysis is used to predict the blade-to-blade flow in a centrifugal compressor impeller which contains splitters (half vanes). The presence of solid boundaries in the flow field and the stagnation points associated with it are treated by assuming that the flow around the stagnation point is isentropic. This removes the instability which the matrix through flow method suffers when stagnation points are encountered within the flow field. The splitters in the present work have the same profile with the full blades. Three different geometries are tested. In the first, the leading edge is 3 mm from the eye, the next is 6 mm, and the third has the leading edge at the exit of the inducer. The calculations show that the differences shown between the three cases are linked with different circumferential components of velocity. The geometry, therefore, of the leading edge is of basic importance in the development of the velocity profiles inside the different channels of the impeller. It is also shown that the distance between the eye of the impeller and the leading edge of the splitter does not affect the flow greatly as long as the leading edge is within the axial part of the impeller. The presence of splitters in general is shown to reduce the width of the suction side boundary layer.

Experimental and Numerical Investigations on a High Pressure Ratio Centrifugal Compressor

2005 ◽  
Author(s):  
Jae Ho Choi ◽  
Ok Suck Sung ◽  
Seung-Bae Chen ◽  
Jin Shik Lim
Keyword(s):  
Centrifugal Compressor ◽  
Performance Test ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Design Flow ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Compressor Stage

An aerodynamic design, flow analysis and performance test of a pressure ratio 4:1 centrifugal compressor are presented in this paper. The compressor is made up of a centrifugal impeller, a two-stage diffuser consisted of radial and axial types. The impeller has a 45 degree backswept angle and the design running tip clearance is 5% of impeller exit height. Two types of diffusers are designed for this compressor. Three-dimensional numerical analysis is performed to analyze the flows in the impeller, diffuser and deswirler considering the impeller tip clearance. A test module and rig facilities for the compressor stage performance test are designed and fabricated. The overall compressor stage performances as well as the static pressure fields on the impeller and diffuser are measured. Two diffusers of wedge and airfoil types are tested with an impeller. The calculation and test results show the airfoil diffuser has the better aerodynamic characteristics than those of wedge diffuser in the studied models.

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