Enhancement of Centrifugal Compressor Operating Range by Control of Inlet Recirculation With Inlet Fins

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Hideaki Tamaki ◽  
Masaru Unno ◽  
Ryuuta Tanaka ◽  
Satoshi Yamaguchi ◽  
Yohei Ishizu
Keyword(s):  
Centrifugal Compressor ◽  
Stability Limit ◽  
Great Promise ◽  
Low Speed ◽  
Operating Range ◽  
Surge Margin ◽  
Compressor Inlet ◽  
Qualitative Effect ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

The operating points of a turbocharger compressor tend to approach or cross its surge line while an engine is accelerating, particularly under low-engine speed conditions, hence the need for an acceptable surge margin under low compressor-speed conditions. A method shifting the stability limit on a compressor low-speed line toward a lower flow rate is expected and inlet recirculation is often observed in a centrifugal compressor with a vaneless diffuser near a surge and under a low compressor-speed condition. First, examples of inlet recirculation were introduced in this paper, whereupon the effect of inlet recirculation on compressor characteristic was discussed by 1D consideration and the potential shown for growth of inlet recirculation to destabilize compressor operations. Accordingly, this study focused on suppressing the effect of inlet recirculation on compressor characteristics using small fins mounted in a compressor-inlet pipe, and examining whether they enhance the compressor operating range under low-speed conditions. Small fins are known as inlet fins in this paper. According to test results, they showed great promise in enhancing the compressor operating range during inlet recirculation. Besides, attempts were also made to investigate the qualitative effect of inlet fins on flow fields using computational fluid dynamics (CFD) and the disadvantages of inlet fins were also discussed.

Enhancement of Centrifugal Compressor Operating Range by Control of Inlet Recirculation With Inlet Fins

2015 ◽  
Author(s):  
Hideaki Tamaki ◽  
Masaru Unno ◽  
Ryuuta Tanaka ◽  
Satoshi Yamaguchi ◽  
Yohei Ishizu
Keyword(s):  
Centrifugal Compressor ◽  
Stability Limit ◽  
Great Promise ◽  
Low Speed ◽  
Operating Range ◽  
Surge Margin ◽  
Compressor Inlet ◽  
Qualitative Effect ◽  
The Stability ◽  
Operating Points

The operating points of a turbocharger compressor tend to approach or cross its surge line while an engine is accelerating, particularly under low-engine speed conditions, hence the need for an acceptable surge margin under low compressor-speed conditions. A method shifting the stability limit on a compressor low-speed line toward a lower flow rate is expected and inlet recirculation is often observed in a centrifugal compressor with a vaneless diffuser near a surge and under a low compressor-speed condition. First, examples of inlet recirculation were introduced in this paper, whereupon the effect of inlet recirculation on compressor characteristic was discussed by 1-D consideration and the potential shown for growth of inlet recirculation to destabilize compressor operations. Accordingly, this study focused on suppressing the effect of inlet recirculation on compressor characteristics using small fins mounted in a compressor-inlet pipe, and examining whether they enhance the compressor operating range under low-speed conditions. Small fins are known as inlet fins in this paper. According to test results, they showed great promise in enhancing the compressor operating range during inlet recirculation. Besides, attempts were also made to investigate the qualitative effect of inlet fins on flow fields using CFD and the disadvantages of inlet fins were also discussed.

Effect of Exit Pressure Pulsation on the Performance and Stability Limit of a Turbocharger Centrifugal Compressor

2016 ◽  
Author(s):  
Maria Esperanza Barrera-Medrano ◽  
Peter Newton ◽  
Ricardo Martinez-Botas ◽  
Srithar Rajoo ◽  
Isao Tomita ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Flow Instability ◽  
Combustion Engine ◽  
Stability Limit ◽  
Intermittent Flow ◽  
Limited Information ◽  
Surge Margin ◽  
Compressor Surge ◽  
Compressor Inlet ◽  
The Stability

It is well known that compressor surge imposes a significant limit on the flow range of a turbocharged internal combustion engine. The centrifugal compressor is commonly placed upstream of the inlet manifold and hence, it is exposed to the intermittent flow regime of the inlet valves. Surge phenomena has been well studied over the past decades, there still remains limited information with regards to the unsteady impact caused by the inlet valves. This study presents an experimental evaluation of such a situation. Engine representative pulses are created by a downstream system comprising a large volume, two rotating valves, a throttle valve and the corresponding pipe network. Different pulsation levels are characterized by means of their frequency and the corresponding amplitude at the compressor inlet. The stability limit of the system under study is evaluated with reference to the parameter B proposed by Greitzer [7–9]. B describes the dynamics of the compression system in terms of volume, area, equivalent length and compressor tip speed as well as the Helmholtz frequency of the system. For a given compressor, as B goes beyond a critical value, the system will exhibit surge as the result of the flow instability progression. The reduced frequency analysis shows that the scroll-diffuser operates in an unsteady regime, while the impeller is nearly quasi-steady. In the vicinity of the surge point, under a pulsating flow, the instantaneous operation of the compressor showed significant excursions into the unstable side of the surge line. Furthermore, it has been found that the presence of a volume in the system has the greatest effect on the surge margin of the compressor under the unsteady conditions.

Aerodynamics of a Centrifugal Compressor With a Double Sided Impeller

2011 ◽  
Author(s):  
Vai-Man Lei
Keyword(s):  
Centrifugal Compressor ◽  
Stability Limit ◽  
Low Flow ◽  
Recirculation Flow ◽  
Flow Capacity ◽  
Operation Modes ◽  
Compressor Inlet ◽  
Parallel Mode ◽  
The Stability ◽  
Ported Shroud

A double sided impeller, which consists of two impellers arranged in a back-to-back configuration with the backdisks eliminated, enables a single centrifugal compressor to have flow capacity similar to two compressors working in parallel but with a smaller packaging size. It reduces inertia of the rotating group and helps improve transient response. The smaller impeller diameter also enhances turbine performance by improving the compressor-turbine matching. These attributes are very attractive for automotive turbocharging applications. As a consequence of a common compressor inlet and diffuser, the two compressor sides interact and two operation modes exist. In the parallel mode, the two compressor sides work under comparable condition and the overall compressor behaves similar to a conventional compressor. As flow rate is reduced below a transition value, the system operates in a single-compressor mode with one compressor side flowing significantly more. The compressor side that flows more operates away from the stability limit and the side with low flow remains stable because of heavy recirculation flow with a ported shroud. Characteristics of the two operation modes are elucidated with test and CFD data.

Numerical Prediction of Centrifugal Compressor Stability Limit

2017 ◽  
Author(s):  
Mauro Carretta ◽  
Carlo Cravero ◽  
Davide Marsano
Keyword(s):  
Design Process ◽  
Centrifugal Compressor ◽  
Stability Limit ◽  
Numerical Prediction ◽  
Compressor Stage ◽  
Operating Range ◽  
Depth Analysis ◽  
Turbine Component ◽  
Computationally Intensive ◽  
The Stability

The compressor operating range is a crucial performance parameter for the design and development of such a gas turbine component. During the design phase it is of utmost importance to be able to predict or estimate the limit mass flow rate, for a given speed line, that will form the surge line and that will influence the overall operating range and matching capabilities of the compressor. CFD simulations are routinely used for the compressor analysis and strongly embedded into the design process. Nevertheless, the ability of a CFD model to accurately predict the surge limit without the need of a massively expensive full 3D unsteady simulation of the centrifugal compressor stage is still an open issue. Moreover in a design process it is very cumbersome to require series of computationally intensive simulations for a 3D geometry that is still under development. In the present work, the use of a CFD approach for the numerical prediction of the stability limit of centrifugal compressors is presented. The proposed approach is applied to different centrifugal stages with vaned diffusers and the obtained surge lines are compared to available experimental datasets. An in-depth analysis of the compressor stage stability limits due to its different components is presented and the use of fully 3D unsteady simulations for the complete stage are discussed to give an additional insight into the phenomenon.

The Effect of Inlet Distortion on the Performance Characteristics of a Centrifugal Compressor

1983 ◽  
Vol 105 (2) ◽  
pp. 223-230 ◽  
Author(s):  
I. Ariga ◽  
N. Kasai ◽  
S. Masuda ◽  
Y. Watanabe ◽  
I. Watanabe
Keyword(s):  
Centrifugal Compressor ◽  
Total Pressure ◽  
Performance Characteristics ◽  
Performance Tests ◽  
Velocity Measurements ◽  
Test Rig ◽  
Low Speed ◽  
Inlet Distortion ◽  
Surge Margin ◽  
The Given

The present paper concerns itself with the effects of total pressure (and thus velocity) distortion on performance characteristics and surge margin of centrifugal compressors. Both radial and circumferential distortions were investigated. The performance tests as well as the velocity measurements within the impeller passages were carried out with a low-speed compressor test rig with the inlet honeycomb as the distortion generators and compared with the case of “no distortion” as a datum. The results indicated that the inlet distortion exerted unfavorable influences on the efficiency and the surge margin of the given compressor, though the influence of the radial distortion was much stronger than that of the circumferential one. Various distortion indices were further examined in order to correlate the performance to the inlet distortion.

An Investigation of the Stability Enhancement of a Centrifugal Compressor Stage Using a Porous Throat Diffuser

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Lee Galloway ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Daniel Rusch ◽  
Klemens Vogel ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
Flow Rates ◽  
Stall Inception ◽  
Centrifugal Compressor Stage ◽  
Operating Range ◽  
Stable Operating ◽  
The Stability ◽  
Circumferential Pressure

The stable operating range of a centrifugal compressor stage of an engine turbocharger is limited at low mass flow rates by aerodynamic instabilities which can lead to the onset of rotating stall or surge. There have been many techniques employed to increase the stable operating range of centrifugal compressor stages. The literature demonstrates that there are various possibilities for adding special treatments to the nominal diffuser vane geometry, or including injection or bleed flows to modify the diffuser flow field in order to influence diffuser stability. One such treatment is the porous throat diffuser (PTD). Although the benefits of this technique have been proven in the existing literature, a comprehensive understanding of how this technique operates is not yet available. This paper uses experimental measurements from a high pressure ratio (PR) compressor stage to acquire a sound understanding of the flow features within the vaned diffuser which affect the stability of the overall compression system and investigate the stabilizing mechanism of the porous throat diffuser. The nonuniform circumferential pressure imposed by the asymmetric volute is experimentally and numerically examined to understand if this provides a preferential location for stall inception in the diffuser. The following hypothesis is confirmed: linking of the diffuser throats via the side cavity equalizes the diffuser throat pressure, thus creating a more homogeneous circumferential pressure distribution, which delays stall inception to lower flow rates. The results of the porous throat diffuser configuration are compared to a standard vaned diffuser compressor stage in terms of overall compressor performance parameters, circumferential pressure nonuniformity at various locations through the compressor stage and diffuser subcomponent analysis. The diffuser inlet region was found to be the element most influenced by the porous throat diffuser, and the stability limit is mainly governed by this element.

Numerical and Experimental Investigation of the CeCOST Swirl Burner

2018 ◽  
Author(s):  
Erdzan Hodzic ◽  
Senbin Yu ◽  
Arman Ahamed Subash ◽  
Xin Liu ◽  
Xiao Liu ◽  
...  
Keyword(s):  
High Speed ◽  
Swirling Flow ◽  
Combustion Process ◽  
Stability Limit ◽  
Swirl Burner ◽  
Current Configuration ◽  
Stable Case ◽  
Eddy Simulation ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

Clean technology has become a key feature due to increasing environmental concerns. Swirling flows, being directly associated with combustion performance and hence minimized pollutant formation, are encountered in most propulsion and power-generation combustion devices. In this study, the development process of the conceptual swirl burner developed at the Swedish National Centre for Combustion and Technology (CeCOST), is presented. Utilizing extensive computational fluid dynamics (CFD) analysis, both the lead time and cost in manufacturing of the different burner parts were significantly reduced. The performance maps bounded by the flashback and blow-off limits for the current configuration were obtained and studied in detail using advanced experimental measurements and numerical simulations. Utilizing high speed OH-chemiluminescence, OH/CH2O-PLIF and Large Eddy Simulation (LES), details of the combustion process and flame-flow interaction are presented. The main focus is on three different cases, a stable case, a case close to blow-off and flashback condition. We show the influence of the flame on the core flow and how an increase in swirl may extend the stability limit of the anchored flame in swirling flow burners.

scholarly journals The Effect of Variable Geometry on the Operating Range and Surge Margin of a Centrifugal Compressor

1976 ◽  
Author(s):  
A. Whitfield ◽  
F. J. Wallace ◽  
R. C. Atkey
Keyword(s):  
Centrifugal Compressor ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Variable Geometry ◽  
Vaneless Diffuser ◽  
Flow Rates ◽  
Lower Flow ◽  
Operating Range ◽  
Surge Margin ◽  
Isentropic Efficiency

Two variable geometry techniques have been applied to a small turbocharger compressor, with the objective of trying to move the peak pressure ratio operating point to lower flow rates, thereby yielding a broad flow range map. Variable prewhirl guide vanes and variable vaneless diffuser passage height have been studied separately. The results obtained with both techniques are compared and the relative merits and demerits with respect to improved flow range and isentropic efficiency penalties are considered.

Design and Experimental Study on the Surge Performance Improvement by the Effects of Bleed Slot Casing of a Centrifugal Compressor

2014 ◽  
Author(s):  
Hong Won Kim ◽  
Jae Hoon Chung ◽  
Hyo Seong Lee ◽  
Min Ouk Choi
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Design Parameters ◽  
Navier Stokes Equations ◽  
Operating Range ◽  
Surge Margin ◽  
Commercial Code

The primary design goal of a compressor is focused on improving efficiency. Secondary objective is to widen the compressor’s operating range. This paper presents a numerical and experimental investigation of the influence of the bleed slot to enlarge operating range for the 1.2MW class centrifugal compressor installed in a turbocharger. The main design parameters of the bleed slot casing are upstream slot position, inlet pipe slope, downstream slot position and width. The DOE (design of experiment) method was carried out to optimize the casing design. Numerical analyses were done by the commercial code ANSYS-CFX based on the three dimensional Reynolds-averaged Navier-Stokes equations. From the analysis, as the downstream slot position and width are smaller and upstream position is located away from impeller inlet, efficiency and pressure ratio are increased. Experimental works were done with and without the bleed slot casing. The simulation results were in good agreement with the test data. In case without the bleed slot casing, the surge margin value came out to be only 11.8% but with the optimized bleed slot design, the surge margin reached 23%. Therefore, the surge margin increase of 11.2% was achieved.

scholarly journals The Effect of Inlet Distortion on the Performance Characteristics of a Centrifugal Compressor

1982 ◽  
Author(s):  
I. Ariga ◽  
N. Kasai ◽  
S. Masuda ◽  
Y. Watanabe ◽  
I. Watanabe
Keyword(s):  
Centrifugal Compressor ◽  
Total Pressure ◽  
Performance Characteristics ◽  
Performance Tests ◽  
Velocity Measurements ◽  
Test Rig ◽  
Low Speed ◽  
Inlet Distortion ◽  
Surge Margin ◽  
The Given

The present paper concerns itself with the effects of total pressure (and thus velocity) distortion on performance characteristics and surge margin of centrifugal compressors. Both radial and circumferential distortions were investigated. The performance tests as well as the velocity measurements within the impeller passages were carried out with a low speed compressor test rig with the inlet honeycomb as the distortion generators and compared with the case of “no distortion” as a datum. The results indicated that the inlet distortion exerted unfavorable influences on the efficiency and the surge margin of the given compressor, though the influence of the radial distortion was much stronger than that of the circumferential one. Various distortion indices were further examined in order to correlate the performance to the inlet distortion.

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