Losses in Vaneless Diffusers of Centrifugal Compressors and Pumps: Analysis, Experiment, and Design

1966 ◽  
Vol 88 (1) ◽  
pp. 49-60 ◽  
Author(s):  
J. P. Johnston ◽  
R. C. Dean
Keyword(s):  
Experimental Data ◽  
Centrifugal Compressor ◽  
Friction Loss ◽  
Sudden Expansion ◽  
Centrifugal Compressors ◽  
One Dimensional ◽  
Complex Theory ◽  
Loss Analysis ◽  
Analysis Experiment ◽  
Vaneless Diffusers

Two simple analyses are developed to predict losses in centrifugal compressor (or pump) vaneless diffusers: (a) One-dimensional, axisymmetric friction loss and (b) sudden-expansion mixing to account for losses in the diffuser caused by wakes of separated impeller blades. It is shown that these theories may be substituted for the more complex theory of Dean and Senoo [5]. Some experimental data are included to show the validity of the friction-loss analysis. Finally, the utility of the analyses in design is demonstrated.

scholarly journals A Method of Predicting the Energy Losses in Vaneless Diffusers of Centrifugal Compressors

1989 ◽  
Author(s):  
Huashu Dou
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Total Energy ◽  
Wall Friction ◽  
Energy Losses ◽  
Flow Conditions ◽  
Centrifugal Compressors ◽  
Flow Losses ◽  
Vaneless Diffusers ◽  
Good Agreement

The flow losses in the veneless diffusers of centrifugal compressors is investigated. It is found that the total energy loss in vaneless diffusers is a function of Bsin2 α0 when inlet flow conditions and radius ratio between inlet and outlet are given. A wall friction coefficient equation is derived and a method of predicting the total energy loss excepting mixing loss is presented. A comparison is made between results obtained from this method and experimental data generated by the author as well as data from the literature. Good agreement is obtained.

Effect of Impeller-Extended Shrouds on Centrifugal Compressor Performance as a Function of Specific Speed

1983 ◽  
Vol 105 (3) ◽  
pp. 457-465 ◽  
Author(s):  
L. Sapiro
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
Gas Compression ◽  
Blade Tip ◽  
Compressor Performance ◽  
The Subject ◽  
Specific Speed ◽  
Vaneless Diffusers ◽  
Outside Diameter

Centrifugal compressors for gas compression applications usually employ low-pressure ratio, backward-swept impellers with vaneless diffusers. To increase the compressor flow range and speed, impeller blades are occasionally trimmed, resulting in an extended shroud configuration. The effect of extended front and back impeller shrouds on the performance of centrifugal compressors with vaneless diffusers, and the variation of this effect as a function of specific speed, is thus of concern and is the subject of this paper. An investigation was carried out on two backward-swept shrouded impellers of common blade tip and inducer hub diameters, but different inducer tip diameters (corresponding to low and high specific speeds), with the front and back shrouds extending 20 percent above the blade’s outside diameter.

Experimental and Numerical Analysis of the Secondary Flow Across the Interphase Balance Drum of a High Pressure Back-to-Back Centrifugal Compressor

2017 ◽  
Author(s):  
Carmine Carmicino ◽  
Francesco Maiuolo ◽  
Emanuele Rizzo
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Numerical Analysis ◽  
Pressure Distribution ◽  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Local Pressure ◽  
Flow Angle ◽  
One Dimensional ◽  
Honeycomb Seal

With the major aim of gathering information on the machine lateral stability in high pressure-high density conditions, and of assessing the prediction capabilities of the in-house design tools and overall process, a back-to-back centrifugal compressor has been instrumented and tested in several operating conditions. The present paper focuses on the secondary flows across the interphase balance drum of the back-to-back compressor, where the sealing is accomplished with a honeycomb seal. The compressor interphase section has been instrumented with dedicated special probes for the clearance measurement associated to pressure and flow angle probes in order to characterize pressure distributions and swirl variations depending on the specific operating range. The experimental data acquired over the machine operation have been compared with a three-dimensional steady-state numerical analysis results obtained from the simulation, carried out with a Reynolds averaged Navier-Stokes (RANS) approach, of the flowfield in the complex interphase secondary system composed by the impeller cavities and the honeycomb seal. This paper addresses the comparison between numerical results and experimental data, which allowed the matching of models with experiments in terms of pressure distribution and the complex flowfield. Finally, all the data have been used to validate an in-house one-dimensional flow network solver for pressure distribution and leakage flow calculations along cavities and seals. Results have shown a general good agreement between measured data and calculation output. In particular, computational fluid dynamic analysis provided detailed pressure and velocity distributions that allowed gaining insight in the physics of such a complex region. The one-dimensional model has been demonstrated to be a fast and reliable tool to well predict local pressure variations inside cavities and seals and, consequently, the residual axial thrust.

Investigation of a Centrifugal Compressor Stage With Two Volutes and the Same Impeller

2003 ◽  
Author(s):  
Yinghui Dai ◽  
Abraham Engeda ◽  
Michael Cave ◽  
Jean-Luc Di Liberti
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Centrifugal Compressor ◽  
Internal Flow ◽  
Sudden Expansion ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
Compressor Impeller ◽  
Overall Performance ◽  
Good Agreement

Volute scroll, conic diffuser and sudden expansion discharge loss account for 4–6 points of efficiency decrement in a typical centrifugal compressor stage. The flow in a volute is highly complex. It is strongly believed that understanding of the detailed flow structure in a volute will provide insights on minimizing the losses by isolating the mechanisms that contributes to entropy generation. The result will be a more efficient centrifugal compressor product for customers and users and a product at higher profitability levels for manufacturers. This paper presents the experimental and numerical investigation on the matching of two different overhung volutes to the same centrifugal compressor impeller. The experimental data were measured from flange to flange firstly, then three Kiel probes were installed on pinch position circumferentially. At the same time, a detailed numerical simulation of the performance of the two volutes has been carried out. A computational model, using the k-ε turbulence model and the wall function, has been used to predict the internal flow of the both volutes. A good agreement between experimental data and numerical simulation results is found. The overall performance of the two volutes was also discussed in detail.

Mean Streamline Aerodynamic Performance Analysis of Centrifugal Compressors

1995 ◽  
Vol 117 (3) ◽  
pp. 360-366 ◽  
Author(s):  
R. H. Aungier
Keyword(s):  
Experimental Data ◽  
Performance Analysis ◽  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Validation Studies ◽  
Prediction Models ◽  
Aerodynamic Performance ◽  
Performance Data ◽  
Centrifugal Compressors ◽  
Test Uncertainty

Aerodynamic Performance prediction models for centrifugal compressor impellers are presented. In combination with similar procedures for stationary components, previously published in the open literature, a comprehensive mean streamline performance analysis for centrifugal compressor stages is provided. The accuracy and versatility of the overall analysis is demonstrated for several centrifugal compressor stages of various types, including comparison with intrastage component performance data. Detailed validation of the analysis against experimental data has been accomplished for over a hundred stages, including stage flow coefficients from 0.009 to 0.15 and pressure ratios up to about 3.5. Its application to turbocharger stages includes pressure ratios up to 4.2, but with test uncertainty much greater than for the data used in the detailed validation studies.

Investigation of Off-Design Performance of Vaned Diffusers in Centrifugal Compressors: Part I — A Channel-Wedge Diffuser

2002 ◽  
Author(s):  
JongSik Oh
Keyword(s):  
Experimental Data ◽  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Limited Range ◽  
Design Parameters ◽  
Centrifugal Compressors ◽  
Design Point ◽  
Numerical Investigations ◽  
Design Performance

Experimental and numerical investigations of the off-design performance of a simple channel-wedge diffuser in a small centrifugal compressor are presented. Surge and choke conditions as well as design point are considered using somewhat limited range of experimental data and also supplementary 3D CFD results. Some critical meanline design parameters’ behavior is investigated numerically, to render the basis for improved modelings in the meanline performance prediction.

Effect of Impeller Extended Shrouds on Centrifugal Compressor Performance as a Function of Specific Speed

1982 ◽  
Author(s):  
L. Sapiro
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
Gas Compression ◽  
Blade Tip ◽  
Compressor Performance ◽  
The Subject ◽  
Specific Speed ◽  
Vaneless Diffusers ◽  
Outside Diameter

Centrifugal compressors for gas compression applications usually employ low-pressure ratio, backward-swept impellers with vaneless diffusers. To increase the compressor flow range and speed, impeller blades are occasionally trimmed, resulting in an extended shroud configuration. The effect of extended front and back impeller shrouds on the performance of centrifugal compressors with vaneless diffusers, and the variation of this effect as a function of specific speed, is thus of concern and is the subject of this paper. An investigation was carried out on two backward-swept shrouded impellers of common blade tip and inducer hub diameters, but different inducer tip diameters (corresponding to low and high specific speeds), with the front and back shrouds extending 20 percent above the blade’s outside diameter.

scholarly journals Design and Performance Evaluation of a Very Low Flow Coefficient Centrifugal Compressor

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Yongsheng Wang ◽  
Feng Lin ◽  
Chaoqun Nie ◽  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
Cfd Simulation ◽  
Volume Flow Rate ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Low Flow ◽  
Centrifugal Compressors ◽  
Lower Efficiency ◽  
One Dimensional ◽  
Low Flow Coefficient

Very low flow coefficient centrifugal compressors are often applied as the last stages of multistage compressors. Due to the lower volume flow rate, the flow channels in the impeller and diffuser are so narrow that friction loss becomes the main factor, which leads to lower efficiency than that of other stages in the same compressors. In addition, most of design methods are generally based on medium flow coefficient centrifugal compressors. Taking on researches on the low flow coefficient centrifugal compressors is significant and necessary. One-dimensional (1D) code, consisting of design and analysis parts, is developed in this study to provide basic geometric data and predict the entire performance of centrifugal compressor. Three-dimensional geometry of the impeller is built. CFD simulation is carried out as well to be compared with 1D prediction. With the continuous geometry adjustment, the final performance of the centrifugal compressor will be fixed once the performance discrepancy between CFD and one-dimensional code is acceptable. The details on the flow field within impeller will be presented through CFD.

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