Experimental and Theoretical Study of Surge in a Small Centrifugal Compressor

1981 ◽  
Vol 103 (3) ◽  
pp. 391-395 ◽  
Author(s):  
K. E. Hansen ◽  
P. Jo̸rgensen ◽  
P. S. Larsen
Keyword(s):  
Relaxation Time ◽  
Centrifugal Compressor ◽  
Theoretical Study ◽  
Stability Limit ◽  
Finite Amplitude ◽  
Axial Compressors ◽  
Lumped Parameter ◽  
Model Equations ◽  
The Stability ◽  
The One

Experimental results for deep surge in a small single-stage centrifugal compressor are compared to predictions based on the lumped parameter Greitzer model developed for axial compressors. Both negative and positive flow branches of the steady characteristic, being essential for the model, were measured. Predictions are in fair agreement with data when using a relaxation time smaller than the one proposed for axial compressors. The stability limit of the model equations have been studied for finite amplitude disturbances.

Detection of Precursor Waves Announcing Stall in Two 3-Stage Axial Compressors

1998 ◽  
Author(s):  
F. Grauer ◽  
W. Volgmann ◽  
H. Stoff ◽  
T. Breuer
Keyword(s):  
Pressure Fluctuations ◽  
Safety Margin ◽  
Stability Limit ◽  
Rotating Stall ◽  
Time Dependent ◽  
Axial Compressors ◽  
Performance Map ◽  
Fourier Transform Methods ◽  
The Stability ◽  
Stall Control

Rotating stall and surge limit the operating range of a compressor towards low throughflow and high pressure in the performance map. Usually a safety margin must be observed to prevent the compressor from entering unintentionally aerodynamic instabilities. As the range of highest performance and efficiency lies in the vicinity of the stability limit, efforts concentrate on recognizing imminent onset of unstable operation prior to its occurrence. The present investigation centers on means of detecting information about onsetting instability from signals of pressure fluctuations in two transonic medium-pressure axial compressors of 3 stages. Fourier-transform-methods as well as artificial neural networks are applied for the data reduction of the time-dependent pressure signals. The methods of investigation presented here detected stall precursors announcing the onset of instability. Some of them seem appropriate to be used in connection with active stall control.

The Operational Stability of a Centrifugal Compressor and Its Dependence on the Characteristics of the Subcomponents

1994 ◽  
Vol 116 (2) ◽  
pp. 250-259 ◽  
Author(s):  
R. Hunziker ◽  
G. Gyarmathy
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Field ◽  
Dynamic Instability ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Pressure Measurements ◽  
The Stability ◽  
Inlet Angle

A centrifugal compressor was tested with three different diffusers with circular-arc vanes. The vane inlet angle was varied from 15 to 30 deg. Detailed static wall pressure measurements show that the pressure field in the diffuser inlet is very sensitive to flow rate. The stability limit regularly occurred at the flow rate giving the maximum pressure rise for the overall stage. Mild surge arises as a dynamic instability of the compression system. The analysis of the pressure rise characteristic of each individual subcomponent (impeller, diffuser inlet, diffuser channel,...) reveals their contribution to the overall pressure rise. The diffuser channels play an inherently destabilizing role while the impeller and the diffuser inlet are typically stabilizing. The stability limit was mainly determined by a change in the characteristic of the diffuser inlet. Further, the stability limit was found to be independent of the development of inducer-tip recirculation.

scholarly journals Study on Two Types of Stall Patterns in a Centrifugal Compressor with a Wide Vaneless Diffuser

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1251
Author(s):  
Qian Zhang ◽  
Liang Zhang ◽  
Qiuhong Huo ◽  
Lei Zhang
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Propagation Speed ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Vaneless Diffusers ◽  
Stall Cells ◽  
The Stability ◽  
The One

Two types of stall patterns in the centrifugal compressor with a wide vaneless diffuser were numerically studied in this paper. We carried out kinds of three-dimensional numerical simulations of the instability process in wide vaneless diffusers with different radius ratios. The results show that there are two kinds of stall patterns in wide vaneless diffusers with different radius ratios. For a short diffuser with a radius ratio of 1.5, the speed of the propagation of stalled cells is relatively high, and the propagation speed and frequency of stall cells do not change with the decrease in the flow rate. For a long diffuser with a radius ratio of 1.8, the propagation velocity of stall cells is smaller to the one in the short diffuser, and increases with the decrease in flow rate. For wide vaneless diffusers with different radius ratios, the main factor causing stall is the outlet reflux. Reducing the radius ratio of the wide vaneless diffuser has an important influence on the stability of the centrifugal compressor.

Assessment of Steady and Unsteady Model Predictions for a Subsonic Centrifugal Compressor Stage

2012 ◽  
Author(s):  
Y. Bousquet ◽  
X. Carbonneau ◽  
I. Trebinjac
Keyword(s):  
Centrifugal Compressor ◽  
Industrial Development ◽  
Pressure Ratio ◽  
Stability Limit ◽  
Compressor Stage ◽  
Common Procedure ◽  
Centrifugal Compressor Stage ◽  
Steady Simulation ◽  
The Stability ◽  
High Level

The most common procedure to obtain the performance of a centrifugal compressor in an industrial development process is based on the use of a steady RANS model with the mixing-plane approach. However some phenomena such as the flow interaction between the impeller and the diffuser can be the source of unsteady effects which can affect the steady model prediction. This paper investigates the ability of a steady simulation to predict the overall performance and the flow structures in a subsonic centrifugal compressor stage by comparison with time-dependent results. Simulations are performed considering three operating points: peak efficiency, close to the stability limit and close to the blockage. The results show that the steady model is accurate enough to predict the stage static-to-total pressure ratio. However, in location where high level of fluctuation is expected, the steady model shows some weakness to predict the time-averaged quantities of the flow structure.

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.

Linear Stability Analysis of LPT Rotor Packets: Part II — Three-Dimensional Results and Mistuning Effects

2004 ◽  
Author(s):  
Roque Corral ◽  
Juan Manuel Gallardo ◽  
Carlos Vasco
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Stability Limit ◽  
Mode Shapes ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Reduced Frequency ◽  
Stability Maps ◽  
The Stability ◽  
The One

Part II of this paper compares the aerodynamic damping of a modern Low Pressure Turbine (LPT) interlock bladed-disc to the one obtained when the blades are welded in pairs through the lateral face of the shroud. The damping is computed using the linearized Reynolds averaged Navier-Stokes equations on a moving grid. It is concluded that the increase in stability of the welded-pair with respect the cantilever configuration due to the modification of the mode-shapes, is smaller than the one due to the overall raise of the reduced frequencies of a bladed-disc with an interlock design. The modification of the flutter boundaries due to mistuning effects is taken into account using the reduced order model known as the Fundamental Mistuning Model (FMM). It is shown that the modification on the stability limit of a interlock bladed-disc is negligible, while for a welded-pair configuration an increase of 0.15% on the critical damping may be expected. Two realistic welded-pair bladed-discs are analysed in this work. It is shown that both are aerodynamically unstable, which is in agreement with the experimental observations. Critical reduced frequency stability maps accounting for mistuning effects are derived for both, freestanding and welded in pairs airfoils. The airfoils are assumed to be identical and mechanically uncoupled. The stabilizing effect of mistuning is also retained in these maps.

On the stability of pipe-Poiseuille flow to finite-amplitude axisymmetric and non-axisymmetric disturbances

1985 ◽  
Vol 158 ◽  
pp. 289-316 ◽  
Author(s):  
P. K. Sen ◽  
D. Venkateswarlu ◽  
S. Maji
Keyword(s):  
Reynolds Number ◽  
Poiseuille Flow ◽  
Finite Amplitude ◽  
Higher Order ◽  
Equilibrium States ◽  
Minimum Threshold ◽  
Threshold Amplitude ◽  
The Stability ◽  
The One ◽  
Axisymmetric Disturbances

The stability of fully developed pipe-Poiseuille flow to finite-amplitude axisymmetric and non-axisymmetric disturbances has been studied using the equilibrium-amplitude method of Reynolds & Potter (1967). In both the cases the least-stable centre-modes were investigated. Also, for the non-axisymmetric case the mode investigated was the one with azimuthal wavenumber equal to one. Many higher-order Landau coefficients were calculated, and the Stuart-Landau series was analysed by the Shanks (1955) method and by using Padé approximants to look for the existence of possible equilibrium states. The results show in both cases that, for each value of the Reynolds number R, there is a preferred band of spatial wavenumbers α in which equilibrium states are likely to exist. Moreover, in both cases it was found that the magnitude of the minimum threshold amplitude for a given R decreases with increasing R. The scales of the various quantities obtained agree very well with those deduced by Davey & Nguyen (1971).

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.

On the stability of elliptical vortex solutions of the shallow-water equations

1987 ◽  
Vol 183 ◽  
pp. 343-363 ◽  
Author(s):  
P. Ripa
Keyword(s):  
Shallow Water ◽  
Shallow Water Equations ◽  
Normal Modes ◽  
Finite Amplitude ◽  
Rossby Number ◽  
Coriolis Parameter ◽  
Vortex Solutions ◽  
The Stability ◽  
The One ◽  
Two Parameters

The one-layer reduced gravity (or ‘shallow water’) equations in the f-plane have solutions such that the active layer is horizontally bounded by an ellipse that rotates steadily. In a frame where the height contours are stationary, fluid particles move along similar ellipses with the same revolution period. Both motions (translation along an elliptical path and precession of that orbit) are anticyclonic and their frequencies are not independent; a Rossby number (R0) based on the combination of both of them is bounded by unity. These solutions may be taken, with some optimism, as a model of ocean warm eddies; their stability is studied here for all values of R0 and of the ellipse eccentricity (these two parameters determine uniquely the properties of the solution).Sufficient stability conditions are derived from the integrals of motion; f-plane flows that satisfy them must be either axisymmetric or parallel. For the model vortex, the circular case simply corresponds to a solid-body rotation, and is found to be stable to finite-amplitude perturbations for all values of R0. This includes R0 > ½, which implies an anticyclonic absolute vorticity.The stability of the truly elliptical cases are studied in the normal modes sense. The height perturbation is an n-order polynomial of the horizontal coordinates; the cases for 0 ≤ n ≤ 6 are analysed, for all possible values of the Rossby number and of the eccentricity. All eddies are stable to perturbations with n ≤ 2. (A property of the shallow-water equations, probably related to the last result, is that a general finite-amplitude n-order field is an exact nonlinear solution for n ≤ 2.) Many vortices - noticeably the more eccentric ones - are unstable to perturbations with n ≥ 3; growth rates are O(R02f) where f is the Coriolis parameter.

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.

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