The Influence of Outlet Stator Part Surface Roughness on the Performance of a Very Low Flow Coefficient Centrifugal Compressor Stage

1996 ◽  
Author(s):  
Jan Paroubek ◽  
Václav Cyrus ◽  
Jiři Kynčl
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Prediction Method ◽  
Stability Limit ◽  
Aerodynamic Performance ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Return Channel ◽  
Low Flow Coefficient

An aerodynamic investigation of the influence of outlet stator part (vaneless diffuser and return channel) surface roughness on aerodynamic performance of a very low flow coefficient centrifugal stage has been carried out. The stage with design inlet flow coefficient 0.007 was tested within the range of stage Mach number Mu2=0.5–1.1. Then the surface quality of outlet stator part was improved and the tests have been repeated. Aerodynamic performance and losses in both vaneless diffuser and return channel with de-swirl vanes were investigated. The values of isentropic head coefficient increased while those of loss coefficient decreased nearly in the whole range of characteristics in the stage with improved surface quality. The detailed pressure recovery in vaneless diffuser in vicinity of design point measured and calculated by the performance prediction method is compared and discussed. The nonsteady flow phenomena were also investigated. The change of dynamic stability limit by improving of surface quality was observed.

Experimental Investigation and Performance Analysis of Six Low Flow Coefficient Centrifugal Compressor Stages

1995 ◽  
Vol 117 (4) ◽  
pp. 585-592 ◽  
Author(s):  
J. Paroubek ◽  
V. Cyrus ◽  
J. Kyncˇl
Keyword(s):  
Development Program ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Test Rig ◽  
Disk Friction ◽  
Return Channel ◽  
And Performance ◽  
Low Flow Coefficient

Some results of a research and development program for centrifugal compressors are presented. Six-stage configurations with low flow coefficient were tested. The stages had channel width parameter b2/D2 = 0.01 and 0.03. For each value of the width parameter, three different impellers with inlet hub to outlet diameter ratio do/D2 = 0.3, 0.4, and 0.5 were designed. Test rig, instrumentation, and data analysis are described. Special attention was devoted to probe calibrations and to evaluation of the leakage, bearing, and disk friction losses. Aerodynamic performance of all tested stages is presented. Slip factors of impellers obtained experimentally and theoretically are compared. Losses in both vaneless diffuser and return channel with deswirl vanes are discussed. Rotating stall was also investigated. Criteria for stall limit were tested.

scholarly journals Experimental Investigation and Performance Analysis of Six Low Flow Coefficient Centrifugal Compressor Stages

1994 ◽  
Author(s):  
J. Paroubek ◽  
V. Cyrus ◽  
J. Kyncl
Keyword(s):  
Rotating Stall ◽  
Development Programme ◽  
Diameter Ratio ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Test Rig ◽  
Return Channel ◽  
And Performance ◽  
Low Flow Coefficient

Some results of a research and development programme for centrifugal compressors are presented. Six stage configurations with low flow coefficient were tested. The stages had channel width parameter bo/D2=0.01 and 0.03. For each value of the width parameter three different impellers with inlet hub to outlet diameter ratio do/D2=0.3, 0.4 and 0.5 were designed. Test rig, instrumentation and data analysis are described. Special attention was devoted to probe calibrations and to evaluation of the leakage, bearing and disc friction losses. Aerodynamic performance of all tested stages is presented. Slip factors of impellers obtained experimentally and theoretically are compared. Losses in both vaneless diffuser and return channel with de-swirl vanes are discussed. Rotating stall was also investigated. Criteria for stall limit were tested.

scholarly journals Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO2

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
C. Lettieri ◽  
N. Baltadjiev ◽  
M. Casey ◽  
Z. Spakovszky
Keyword(s):  
Vortex Shedding ◽  
Supercritical Co2 ◽  
Leading Edge ◽  
Design Strategy ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Vaned Diffuser ◽  
Compressor Design ◽  
Low Flow Coefficient

This paper presents a design strategy for very low flow coefficient multistage compressors operating with supercritical CO2 for carbon capture and sequestration (CCS) and enhanced oil recovery (EOR). At flow coefficients less than 0.01, the stage efficiency is much reduced due to dissipation in the gas-path and more prominent leakage and windage losses. Instead of using a vaneless diffuser as is standard design practice in such applications, the current design employs a vaned diffuser to decrease the meridional velocity and to widen the gas path. The aim is to achieve a step change in performance. The impeller exit width is increased in a systematic parameter study to explore the limitations of this design strategy and to define the upper limit in efficiency gain. The design strategy is applied to a full-scale reinjection compressor currently in service. Three-dimensional, steady, supercritical CO2 computational fluid dynamics (CFD) simulations of the full stage with leakage flows are carried out with the National Institute of Standards and Technology (NIST) real gas model. The design study suggests that a nondimensional impeller exit width parameter b2* = (b2/R)ϕ of six yields a 3.5 point increase in adiabatic efficiency relative to that of a conventional compressor design with vaneless diffuser. Furthermore, it is shown that in such stages the vaned diffuser limits the overall stability and that the onset of rotating stall is likely caused by vortex shedding near the diffuser leading edge. The inverse of the nondimensional impeller exit width parameter b2* can be interpreted as the Rossby number. The investigation shows that, for very low flow coefficient designs, the Coriolis accelerations dominate the relative flow accelerations, which leads to inverted swirl angle distributions at impeller exit. Combined with the two-orders-of-magnitude higher Reynolds number for supercritical CO2, the leading edge vortex shedding occurs at lower flow coefficients than in air suggesting an improved stall margin.

scholarly journals Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO2

2013 ◽  
Author(s):  
C. Lettieri ◽  
N. Baltadjiev ◽  
M. Casey ◽  
Z. Spakovszky
Keyword(s):  
Vortex Shedding ◽  
Supercritical Co2 ◽  
Leading Edge ◽  
Design Strategy ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Vaned Diffuser ◽  
Compressor Design ◽  
Low Flow Coefficient

This paper presents a design strategy for very low flow coefficient multi-stage compressors operating with supercritical CO2 for Carbon Capture and Sequestration (CCS) and Enhanced Oil Recovery (EOR). At flow coefficients less than 0.01 the stage efficiency is much reduced due to dissipation in the gas-path and more prominent leakage and windage losses. Instead of using a vaneless diffuser as is standard design practice in such applications, the current design employs a vaned diffuser to decrease the meridional velocity and to widen the gas path. The aim is to achieve a step change in performance. The impeller exit width is increased in a systematic parameter study to explore the limitations of this design strategy and to define the upper limit in efficiency gain. The design strategy is applied to a full-scale re-injection compressor currently in service. Three-dimensional, steady, supercritical CO2 CFD simulations of the full stage with leakage flows are carried out with the NIST real gas model. The design study suggests that a non-dimensional impeller exit width parameter b2* = (b2/R)ϕ of 6 yields a 3.5 point increase in adiabatic efficiency relative to that of a conventional compressor design with vaneless diffuser. Furthermore, it is shown that in such stages the vaned diffuser limits the overall stability and that the onset of rotating stall is likely caused by vortex shedding near the diffuser leading edge. The inverse of the non-dimensional impeller exit width parameter b2* can be interpreted as the Rossby number. The investigation shows that, for very low flow coefficient designs, the Coriolis accelerations dominate the relative flow accelerations, which leads to inverted swirl angle distributions at impeller exit. Combined with the two-orders-of-magnitude higher Reynolds number for supercritical CO2, the leading edge vortex shedding occurs at lower flow coefficients than in air suggesting an improved stall margin.

Reynolds Number and Roughness Effects on Turbocompressor Performance: Numerical Calculations and Measurement Data Evaluation

2020 ◽  
Author(s):  
Fabian Dietmann ◽  
Michael Casey ◽  
Damian M. Vogt
Keyword(s):  
Reynolds Number ◽  
Measurement Data ◽  
Theoretical Models ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Roughness Effects ◽  
Flow Channels ◽  
Compressor Performance ◽  
Low Flow Coefficient

Abstract Further validation of an analytic method to calculate the influence of changes in Reynolds number, machine size and roughness on the performance of axial and radial turbocompressors is presented. The correlation uses a dissipation coefficient as a basis for scaling the losses with changes in relative roughness and Reynolds number. The original correlation from Dietmann and Casey [6] is based on experimental data and theoretical models. Evaluations of five numerically calculated compressor stages at different flow coefficients are presented to support the trends of the correlation. It is shown that the sensitivity of the compressor performance to Reynolds and roughness effects is highest for low flow coefficient radial stages and steadily decreases as the design flow coefficient of the stage and the hydraulic diameter of the flow channels increases.

Research on Optimization of Cutting Parameters Based on Genetic Algorithm

2011 ◽  
Vol 121-126 ◽  
pp. 4640-4645 ◽  
Author(s):  
Shu Ren Zhang ◽  
Xue Guang Li ◽  
Jun Wang ◽  
Hui Wei Wang
Keyword(s):  
Genetic Algorithm ◽  
Surface Roughness ◽  
Surface Quality ◽  
Bp Neural Network ◽  
Prediction Method ◽  
Cutting Parameters ◽  
Multi Objective Optimization ◽  
Experiment Data ◽  
Optimization Of Cutting Parameters ◽  
Working Efficiency

Three elements of Cutting dosages have a great effect on parts surface quality and working efficiency, the best organization of cutting three elements for parts surface quality must be found before machining, in order to surface roughness and machining cost of parts, multi-objective optimization model is established in this paper, model is solved by using genetic algorithm. Based on the BP neural network of three layers, forecasting model of surface roughness is established. According to existing experiment data and optimized cutting dosages, analysis and prediction of surface roughness is done. Machining experiment is done by using optimized data. The experiment result verifies feasibility of this optimistic method and prediction method of surface roughness.

scholarly journals Numerical characteristics of a centrifugal compressor with a low flow coefficient

2019 ◽  
Vol 140 ◽  
pp. 06010 ◽  
Author(s):  
Aleksey Yablokov ◽  
Ivan Yanin ◽  
Nikolay Sadovskyi ◽  
Yuri Kozhukhov ◽  
Minh Hai Nguyen
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Flow Coefficient ◽  
Ultrahigh Pressure ◽  
Low Flow ◽  
Classical Type ◽  
Numerical Characteristic ◽  
Wall Cell ◽  
Low Flow Coefficient ◽  
Near Wall

The study presents the simulation results of the viscid gas flow in low flow coefficient centrifugal compressor stages. The problem is solved in a stationary formulation using the Ansys CFX software package. The numerical simulation is carried out on three ultrahigh-pressure model stages; two stages have blades of the classical type impeller and one stage is of the bodily type. The value of the conditional flow coefficient is 0.0063 to 0.015. As part of the study, block-structured design meshes are used for all gas channel elements, with their total number being equaled as 13–15 million. During the calculations a numerical characteristic was validated with the results of tests carried out at the Department of Compressor, Vacuum and Refrigeration Engineering of Peter the Great St. Petersburg Polytechnic University. With an increase of inlet pressure as a result of a numerical study, it was found that for a given mathematical model the disk friction and leakage coefficient (1 + βfr + βlk) is overestimated. The analysis of flow in labyrinth seals has shown an increase of total temperature near the discs by 30–50 °С, nevertheless this fact did not influence gas parameters in the behind-the-rotor section. The calculation data obtained with finer design mesh (the first near-wall cell was 0.001 mm) is identical to those obtained with the first near-wall cell 0.01 mm mesh.

The Influence of the Blading Surface Roughness on the Aerodynamic Behavior and Characteristic of an Axial Compressor

1980 ◽  
Vol 102 (2) ◽  
pp. 283-287 ◽  
Author(s):  
K. Bammert ◽  
G. U. Woelk
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Low Flow ◽  
Blade Surface ◽  
Characteristic Curves ◽  
Flow Losses

The conversion of energy in an axial compressor is influenced in great measure by the surface quality of the blading. To achieve low flow losses, the roughness values of the blade surface must be below certain limits. However, the blade surface, which is hydraulically smooth on commissioning of the machine, is in many cases attacked by dirt, corrosion and erosion during operation. For investigation of the influence of the surface quality on the efficiency, flow rate, pressure ratio, and the shifting of the characteristic curves, systematic measurements were taken on a three-stage axial compressor with smooth and uniformly rough blading. The roughness was produced by applying loose emery grain of different grades.

Numerical Investigation on the Labyrinth Seal Design for a Low Flow Coefficient Centrifugal Compressor

2010 ◽  
Author(s):  
Zhiheng Wang ◽  
Liqun Xu ◽  
Guang Xi
Keyword(s):  
Centrifugal Compressor ◽  
Labyrinth Seal ◽  
Flow Coefficient ◽  
Low Flow ◽  
Design Parameters ◽  
Centrifugal Impeller ◽  
Computational Domain ◽  
Cfd Simulations ◽  
Isentropic Efficiency ◽  
Low Flow Coefficient

The leakage flow across the shroud of a centrifugal compressor impeller has an important effect on the compressor’s performance, in particular, in the low flow coefficient compressor. This paper presents the three-dimensional CFD simulations and the Radial Basis Function (RBF) model to investigate the aerodynamic performance of the labyrinth seal as well as the low flow coefficient centrifugal impeller. The CFD simulations are performed on the computational domain consisting of the labyrinth seal and the impeller. The relationship between the leakage loss coefficient and the isentropic efficiency is indicated. With the application of the RBF model, the global sensitivity analysis to the seal geometric design parameters is carried out, and the geometry of the labyrinth seal is optimized. The leakage of the optimized labyrinth seal is reduced remarkably and the impeller’s isentropic efficiency improved by 2% in a wide operating range.

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