A Method to Estimate the Performance Map of a Centrifugal Compressor Stage

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Michael Casey ◽  
Chris Robinson
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Coefficient ◽  
Compressor Stage ◽  
Algebraic Equations ◽  
Centrifugal Compressor Stage ◽  
Novel Approach ◽  
Wide Range ◽  
Performance Map ◽  
Vaneless Diffusers

A novel approach to calculate the performance map of a centrifugal compressor stage is presented. At the design point four nondimensional parameters (the flow coefficient φ, the work coefficient λ, the tip-speed Mach number M, and the efficiency η) characterize the performance. In the new method the performance of the whole map is also based on these four parameters through physically based algebraic equations which require little prior knowledge of the detailed geometry. The variable empirical coefficients in the parameterized equations can be calibrated to match the performance maps of a wide range of stage types, including turbocharger and process compressor impellers with vaned and vaneless diffusers. The examples provided show that the efficiency and the pressure ratio performance maps of turbochargers with vaneless diffusers can be predicted to within ±2% in this way. More uncertainty is present in the prediction of the surge line, as this is very variable from stage to stage. During the preliminary design the method provides a useful reference performance map based on earlier experience for comparison with objectives at different speeds and flows.

A Method to Estimate the Performance Map of a Centrifugal Compressor Stage

2011 ◽  
Author(s):  
Michael Casey ◽  
Chris Robinson
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Coefficient ◽  
Compressor Stage ◽  
Algebraic Equations ◽  
Centrifugal Compressor Stage ◽  
Novel Approach ◽  
Wide Range ◽  
Performance Map ◽  
Vaneless Diffusers

A novel approach to calculate the performance map of a centrifugal compressor stage is presented. At the design point four non-dimensional parameters (the flow coefficient φ, the work coefficient λ, the tip-speed Mach number M and the efficiency η) characterize the performance. In the new method the performance of the whole map is also based on these four parameters through physically-based algebraic equations which require little prior knowledge of the detailed geometry. The variable empirical coefficients in the parameterized equations can be calibrated to match the performance maps of a wide range of stage types, including turbocharger and process compressor impellers with vaned and vaneless diffusers. The examples provided show that the efficiency and the pressure ratio performance maps of turbochargers with vaneless diffusers can be predicted to within ± 2% in this way. More uncertainty is present in the prediction of the surge line, as this is very variable from stage to stage. During the preliminary design the method provides a useful reference performance map based on earlier experience for comparison with objectives at different speeds and flows.

Analysis and Redesign of the Stationary Components for a Low Flow Coefficient Centrifugal Compressor Stage

2009 ◽  
Author(s):  
Zhiheng Wang ◽  
Guang Xi
Keyword(s):  
Centrifugal Compressor ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Meridional Plane ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
Lower Stage ◽  
Wide Range ◽  
Low Flow Coefficient

A low flow coefficient centrifugal compressor stage is characterized by the small relative outlet width, and is often one of the latter stages in the multistage compressor. The low flow coefficient stage is known to give lower stage efficiency in comparison with the conventional stage, which still leaves much more space to be improved with modern tools such as CFD techniques. In the paper the flow in a CO2 centrifugal compressor stage with a low design flow coefficient of 0.008 is simulated based on the 3D viscous CFD codes. The analysis shows the impeller gives a favorable performance over a wide range of low flow coefficient, but the high losses exist in the stationary components and this incurs the poor performance of the whole stage. In this case, the diffuser, the return channel and the meridional plane are redesigned. The redesigned stage has distinct improvements on the performance and the flow structure.

1D and 3D-Design Strategies for Pressure Slope Optimization of High-Flow Transonic Centrifugal Compressor Impellers

2018 ◽  
Author(s):  
A. Hildebrandt ◽  
T. Ceyrowsky
Keyword(s):  
Centrifugal Compressor ◽  
High Flow ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Angle Distribution ◽  
Compressor Stage ◽  
Impeller Blade ◽  
Design Point ◽  
Centrifugal Compressor Stage ◽  
Transonic Centrifugal Compressor

The present paper deals with the numerical and theoretical investigations of the effect of geometrical dimensions and 1D-design parameters on the impeller pressure slope of a transonic centrifugal compressor stage for industrial process application. A database being generated during the multi-objective and multi-point design process of a high flow coefficient impeller, comprising 545 CFD (Computational Fluid Dynamics) designs is investigated in off-design and design conditions by means of RANS (Reynolds Averaged Navier Stokes) simulation of an impeller with vaneless diffuser. For high flow coefficients of 0.16 < phi < 0.18, the CFD-setup has been validated against measurement data regarding stage and impeller performance taken from MAN test rig experimental data for a centrifugal compressor stage of similar flow coefficient. The paper aims at answering the question how classical design parameter, such as the impeller blade angle distribution, impeller suction diameter and camber line length affect the local and total relative diffusion and pressure slope towards impeller stall operation. A second order analysis of the CFD database is performed by cross-correlating the CFD data with results from impeller two-zone 1D modelling and a rapid loading calculation process by Stanitz and Prian. The statistical covariance of first order 1D-analysis parameters such as the mixing loss of the impeller secondary flow, the slip factor, impeller flow incidence is analyzed, thereby showing strong correlation with the design and off-design point efficiency and pressure slope. Finally, guide lines are derived in order to achieve either optimized design point efficiency or maximum negative pressure slope characteristics towards impeller stall operation.

Experimental Validation of a Wide-Range Centrifugal Compressor Stage for Supercritical CO2 Power Cycles

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Timothy C. Allison ◽  
Natalie R. Smith ◽  
Robert Pelton ◽  
Jason C. Wilkes ◽  
Sewoong Jung
Keyword(s):  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Successful Implementation ◽  
Compressor Stage ◽  
Test Results ◽  
Power Cycles ◽  
Casing Treatment ◽  
Centrifugal Compressor Stage ◽  
Operating Range ◽  
Wide Range

Successful implementation of sCO2 power cycles requires high compressor efficiency at both the design-point and over a wide operating range in order to maximize cycle power output and maintain stable operation over a wide range of transient and part-load operating conditions. This requirement is particularly true for air-cooled cycles where compressor inlet density is a strong function of inlet temperature that is subject to daily and seasonal variations as well as transient events. In order to meet these requirements, a novel centrifugal compressor stage design was developed that incorporates multiple novel range extension features, including a passive recirculating casing treatment and semi-open impeller design. This design, presented and analyzed for CO2 operation in a previous paper, was fabricated via direct metal laser sintering and tested in an open-loop test rig in order to validate simulation results and the effectiveness of the casing treatment configuration. Predicted performance curves in air and CO2 conditions are compared, resulting in a reduced diffuser width requirement for the air test in order to match design velocities and demonstrate the casing treatment. Test results show that the casing treatment performance generally matched computational fluid dynamics (CFD) predictions, demonstrating an operating range of 69% and efficiency above air predictions across the entire map. The casing treatment configuration demonstrated improvements over the solid wall configuration in stage performance and flow characteristics at low flows, resulting in an effective 14% increase in operating range with a 0.5-point efficiency penalty. The test results are also compared to a traditional fully shrouded impeller with the same flow coefficient and similar head coefficient, showing a 42% range improvement over traditional designs.

Some Studies on Low Solidity Vaned Diffusers of a Centrifugal Compressor Stage

2005 ◽  
Author(s):  
T. Ch. Siva Reddy ◽  
G. V. Ramana Murty ◽  
Prasad Mukkavilli ◽  
D. N. Reddy
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Pressure Recovery ◽  
Compressor Stage ◽  
Recovery Coefficient ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Centrifugal Compressor Stage ◽  
Pressure Recovery Coefficient

Numerical simulation of impeller and low solidity vaned diffuser (LSD) of a centrifugal compressor stage is performed individually using CFX- BladeGen and BladeGenPlus codes. The tip mach number for the chosen study was 0.35. The same configuration was used for experimental investigation for a comparative study. The LSD vane is formed using standard NACA profile with marginal modification at trailing edge. The performance parameters obtained form numerical studies at the exit of impeller and the diffuser have been compared with the corresponding experimental data. These parameters are pressure ratio, polytropic efficiency and flow angle at the impeller exit where as the parameters those have been compared at the exit of diffuser are the static pressure recovery coefficient and the exit flow angle. In addition, the numerical prediction of the blade loading in terms of blade surface pressure distribution on LSD vane has been compared with the corresponding experimental results. Static pressure recovery coefficient and flow angle at diffuser exit is seen to match closely at higher flows. The difference at lower flows could be due to the effect of interaction between impeller and diffuser combinations, as the numerical analysis was done separately for impeller and diffuser and the effect of impeller diffuser interaction was not considered.

Improving the Accuracy of Tests for Centrifugal Compressor Stage Performance Prediction

2006 ◽  
Author(s):  
Daniele Fiaschi ◽  
Giampaolo Manfrida ◽  
Libero Tapinassi
Keyword(s):  
Special Reference ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Transfer Model ◽  
Compressor Stage ◽  
Stage Design ◽  
Centrifugal Compressor Stage ◽  
Expected Performance ◽  
Total Temperature ◽  
Gas Market

A design of experiment approach was used to solve problems on the new centrifugal compressor stage development test beds at the Nuovo Pignone – GE Oil&Gas premises in Florence, Italy. The company is able to provide centrifugal compressor equipment tailored to the user’s requests, with special reference to the oil & gas market. In order to provide this service, an archive of designs is available which can be adapted to different requirements: CFD is widely used to improve the turbomachinery performance, and on each new stage design extensive fluid dynamics test campaigns are routinely run, in order to confirm the expected performance. Recently inadequacy of the accuracy of the measurements became evident: the cause was traced back to thermal effects which introduced a large uncertainty in the test results, with special reference to machines having large operating Mach number, and low pressure ratio. The present work included: a) The development of a heat transfer model capable of predicting the observed trend of the experimental data. b) The improvement of the accuracy of total temperature measurements, needed to confirm the results of the model. The positive results allow the company to guarantee with increased confidence the expected performance levels.

Study on Aerodynamic Redesign of a High Pressure Ratio Centrifugal Compressor

2010 ◽  
Author(s):  
Chaolei Zhang ◽  
Qinghua Deng ◽  
Zhenping Feng
Keyword(s):  
Centrifugal Compressor ◽  
Cfd Simulation ◽  
Pressure Ratio ◽  
Aerodynamic Performance ◽  
Compressor Stage ◽  
Operation Condition ◽  
Vaned Diffuser ◽  
Centrifugal Compressor Stage ◽  
Optimum Configuration ◽  
Operation Conditions

This paper describes the aerodynamic redesign and optimization of a typical single stage centrifugal compressor, in which the total pressure ratio was improved from the original 4.0 to final 5.0 with the restrictions of keeping the impeller tip diameter, the design rotational speed and the design mass flow rate unchanged. Firstly the backsweep angle and the outlet blade height of the impeller were adjusted and the vaned diffuser was redesigned. Then a sensitivity analysis of the aerodynamic performance correlated to the primary redesign centrifugal compressor stage with respect to the chosen redesign variables was conducted, according to the parameterized results of the impeller and the vaned diffuser. Secondly the impeller and the vaned diffuser were optimized respectively under the stage environment at the design operation condition to improve the stage isentropic efficiency by using a global optimization method which coupled Evolutionary Algorithm (EA) and Artificial Neural Network (ANN), provided by the commercial software NUMECA DESIGN-3D. Subsequently the detailed performance maps of the centrifugal compressor stage corresponding to the primary redesign configuration and the optimum configuration were presented by Computational Fluid Dynamics (CFD) simulation. Finally the flow fields correlated to the centrifugal compressor configurations before and after optimization at the design operation condition were also compared and analyzed in detail. As a result the design target was achieved after the primary redesign, as a 2.7% gain in stage efficiency and a 3.6% increase in stage pressure ratio were obtained when compared with the primary redesign configuration after optimization. Moreover, the aerodynamic performance of the optimum configuration at the off-design operation conditions was also improved.

Flow Studies on a Centrifugal Compressor Stage With Low Solidity Diffuser Vanes

2002 ◽  
Author(s):  
Prasad Mukkavilli ◽  
G. Rama Raju ◽  
A. Dasgupta ◽  
G. V. Ramana Murty ◽  
K. V. Jagadeshwar Chary
Keyword(s):  
Centrifugal Compressor ◽  
Design Flow ◽  
Flow Coefficient ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Centrifugal Compressor Stage ◽  
Setting Angle ◽  
Set Up ◽  
Flow Improvement ◽  
Stagger Angle

Diffusers are found to play a significant role in the performance of centrifugal compressors. Extensive studies have been in progress in various research laboratories for improvement of performance with various types of diffusers. One such effort for study of performance of a centrifugal compressor stage with Low Solidity Diffuser (LSD) vanes is presented in this paper. The study was conducted at a tip mach number of 0.35. An exclusive test rig was set up for carrying out these flow studies. The LSD vane is formed using standard NACA profile with marginal modification at the trailing edge region. The study encompasses the variation of setting angle of the LSD vane and the vane solidity. The effect of solidity and the setting angle on overall stage performance is evaluated in terms of flow coefficient, head coefficient and efficiency normalised with respect to these parameters for the case of vaneless diffuser at design flow. Improvement in performance as well as static pressure recovery was observed with LSD as compared to vaneless diffuser configuration. It is concluded from these studies that there is an optimum solidity and stagger angle for the given stage with LSD vanes for the chosen configuration.

Aerodynamic Design and Rig Test Validation of a High Flow Coefficient Process Centrifugal Compressor Stage

2021 ◽  
Author(s):  
Louis Larosiliere ◽  
Vishal Jariwala ◽  
Kapil Panchal
Keyword(s):  
Centrifugal Compressor ◽  
High Flow ◽  
Design Flow ◽  
Flow Coefficient ◽  
Test Validation ◽  
Lapse Rate ◽  
Compressor Stage ◽  
Aerodynamic Design ◽  
Centrifugal Compressor Stage ◽  
Very High

Abstract Efficient and diametrically compact very high flow coefficient stages with wide operability are desirable for economic reasons in many process multistage centrifugal compressor applications. Such stages present special aerodynamic and mechanical design challenges. There is often a sizeable efficiency lapse rate as well as substantial reduction in useable operating range for traditional stages having design flow coefficients greater than 0.15 and moderate to high machine Mach numbers. This paper describes aerodynamic design and rig test validation of a very high flow coefficient (φ0 = 0.237) process centrifugal compressor stage. Some useful experience of the detailed design work required to navigate certain technical challenges and its rig test validation are reflected in the manuscript. A relatively high machine Mach number (MU ∼ 0.878) mixed-flow shrouded impeller matched with a curved radial vaneless diffuser and return channel was developed. Test results confirmed that the principal aerodynamic design intents were met or exceeded. A sensible design strategy guided by a well-anchored design method is shown to successfully extend an existing stage portfolio to very high-flow coefficients for multistage process centrifugal compressor applications.

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