Structure and Propagation of Rotating Stall in a Single- and a Multi-Stage Axial Compressor

1999 ◽  
Author(s):  
H. M. Saxer-Felici ◽  
A. P. Saxer ◽  
F. Ginter ◽  
A. Inderbitzin ◽  
G. Gyarmathy
Keyword(s):  
Numerical Solutions ◽  
Equations Of Motion ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Water Model ◽  
Two Stage ◽  
Additional Information ◽  
Driving Mechanisms ◽  
Multi Stage ◽  
Stall Cells

The structure and propagation of rotating stall cells in a single- and a two-stage subsonic axial compressor is addressed in this paper using computational and experimental analysis. Unsteady solutions of the 2-D inviscid compressible (Euler) equations of motion are presented for one operating point in the fully-developed rotating stall regime for both a single- and a two-stage compressor. The inviscid assumption is verified by comparing the single-stage 2-D in viscid/compressible solution with an equivalent 2-D viscous (Navier-Stokes) result for incompressible flow. The structure of the rotating stall cell is analyzed and compared for the single- and two-stage cases. The numerical solutions are validated against experimental data consisting of flow visualization and unsteady row-by-row static pressure measurements obtained in a four-stage water model of a subsonic compressor. The CFD solutions supply a link between the observed experimental features and provide additional information on the structure of the stall flow. Based on this study. supporting assumptions regarding the driving mechanisms for the propagation of fully-developed rotating stall cells and their structure are postulated. In methodical respect the results suggest that the inviscid model is able to reproduce the essentials of the flow physics associated with the propagation of fully-developed, full-span rotating stall in a subsonic axial compressor.

scholarly journals Development of Small Rotating Stall in a Single Stage Axial Compressor

1985 ◽  
Author(s):  
K. Mathioudakis ◽  
F. A. E. Breugelmans
Keyword(s):  
Experimental Study ◽  
Rotor Blade ◽  
Axial Compressor ◽  
Propagation Speed ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Blade Surface ◽  
Hot Wire ◽  
Additional Information ◽  
Cell Pattern

In this paper we present the results of a detailed experimental study of the development of small rotating stall, as it appears in a one stage axial compressor. Stationary hot-wire probes are used to measure the variation of amplitude and propagation speed of the disturbances caused by small stall. Measurements near the rotor blade surface with rotating probes provide additional information on the nature of the phenomenon. The development of the cell pattern for different operating conditions is studied. The different character from what is known as “big stall” is demonstrated.

Prediction and Measurement of Rotating Stall Cells in an Axial Compressor

1999 ◽  
Vol 121 (2) ◽  
pp. 365-375 ◽  
Author(s):  
H. M. Saxer-Felici ◽  
A. P. Saxer ◽  
A. Inderbitzin ◽  
G. Gyarmathy
Keyword(s):  
Mass Flow ◽  
Static Pressure ◽  
Axial Compressor ◽  
Rotating Stall ◽  
High Mass ◽  
Operating Point ◽  
Momentum Exchange ◽  
Unstable Regime ◽  
Stall Cells ◽  
Speed Of Propagation

This paper presents a parallel numerical and experimental study of rotating stall cells in an axial compressor. Based on previous theoretical and experimental studies stressing the importance of fluid inertia and momentum exchange mechanisms in rotating stall, a numerical simulation using the Euler equations is conducted. Unsteady two-dimensional solutions of rotating stall behavior are obtained in a one-stage low subsonic axial compressor. The structure and speed of propagation of one fully developed rotating stall cell together with its associated unsteady static pressure and throughflow field distributions are presented. The numerical capture of a stalled flow region starting from a stable high-flow operating point with an axisymmetric flow distribution and evolving at a reduced mass flow operating point into a rotating stall pattern is also discussed. The experimental data (flow visualization, time-averaged and unsteady row-by-row static pressure measurements) acquired in a four-stage water model of a subsonic axial compressor cover a complete characteristic line ranging from high mass flow in the stable regime to zero throughflow. Stall inception is presented together with clearly marked different operating zones within the unstable regime. For one operating point in the unstable regime, the speed of propagation of the cell as well as the static pressure spikes at the front and rear boundaries of the rotating stall cell are compared between computations, measurements, and an idealized theory based on momentum exchange between blade rows entering and leaving the stalled cell. In addition, the time evolution of the pressure trace at the rotor/stator interface is presented. This study seems to support the assumption that the cell structure and general mechanism of full-span rotating stall propagation are essentially governed by inertial effects and momentum exchange between the sound and stalled flow at the cell edges.

scholarly journals Prediction and Measurement of Rotating Stall Cells in an Axial Compressor

1998 ◽  
Author(s):  
H. M. Saxer-Felici ◽  
A. P. Saxer ◽  
A. Inderbitzin ◽  
G. Gyarmathy
Keyword(s):  
Mass Flow ◽  
Static Pressure ◽  
Axial Compressor ◽  
Rotating Stall ◽  
High Mass ◽  
Operating Point ◽  
Momentum Exchange ◽  
Unstable Regime ◽  
Stall Cells ◽  
Speed Of Propagation

This paper presents a parallel numerical and experimental study of rotating stall cells in an axial compressor. Based on previous theoretical and experimental studies stressing the importance of fluid inertia and momentum exchange mechanisms in rotating stall, a numerical simulation using the Euler equations is conducted. Unsteady 2-D solutions of rotating stall behavior are obtained in a one-stage low subsonic axial compressor. The structure and speed of propagation of one fully developed rotating stall cell together with its associated unsteady static pressure and throughflow field distributions are presented. The numerical capture of a stalled flow region starting from a stable high-flow operating point with an axisymmetric flow distribution and evolving at a reduced mass flow operating point into a rotating stall pattern is also discussed. The experimental data (flow visualization, time-averaged and unsteady row-by-row static pressure measurements) acquired in a four-stage water model of a subsonic axial compressor covers a complete characteristic line ranging from high mass flow in the stable regime to zero throughflow. Stall inception is presented together with clearly marked different operating zones within the unstable regime. For one operating point in the unstable regime, the speed of propagation of the cell as well as the static pressure spikes at the front and rear boundaries of the rotating stall cell are compared between computations, measurements and an idealized theory based on momentum exchange between blade rows entering and leaving the stalled cell. In addition, the time-evolution of the pressure trace at the rotor/stator interface is presented. This study seems to support the assumption that the cell structure and general mechanism of full-span rotating stall propagation are essentially governed by inertial effects and momentum exchange between the sound and stalled flow at the cell edges.

Rotating Stall Model and Simulation of Two-Stage Centrifugal Compressors

2007 ◽  
Author(s):  
Lorenzo Scano ◽  
Gianmario L. Arnulfi
Keyword(s):  
Fluid Dynamic ◽  
Experimental Tests ◽  
Stationary Flow ◽  
Computer Code ◽  
Rotating Stall ◽  
Single Stage ◽  
Maximum Efficiency ◽  
Centrifugal Compressors ◽  
Two Stage ◽  
Multi Stage

Often turbo-compressors exhibit the maximum efficiency condition very close to the stall limit, so that it would be highly interesting to have a deep comprehension of this phenomenon. Despite the large diffusion of the multi-stage centrifugal compressors in different fields of the technology, such as natural gas pipe-lines or chemical factories, at the best authors’ knowledge, to date no theoretical model exists for rotating stall in these machines. This paper deals with a model for simulating multi-stage centrifugal compressor flow pattern during rotating stall. The model is not able to capture the stall inception, so the velocity and pressure fields are calculated throughout the machine once rotating stall has developed. The model consists of an implementation of that proposed by Moore for single-stage centrifugal compressors, so the simplifying hypotheses are: irrotational upstream fluid flow, inviscid and incompressible flow, stationary flow in the frame rotating at the same frequency of the stall cell; infinite blades are supposed both in rotors and return channel. Even if these fluid-dynamic hypotheses are really strong, it is worth of note that the reference models for rotating stall simulation in turbo-compressors (namely the Moore’s models) are based, at the present time, on them. In a previous step of this research, the authors utilized a semi-empirical approach, with phases changes between first and second diffuser based on experimental data. Now this hypothesis is removed and the model is fully analytical. The mathematical model is solved by numerical way, leaving the original semi-analytical scheme of Moore, so allowing the stall cell propagation frequency to be calculated. The computer code is written in C language for Linux operating system. It was tested in single-stage configuration with results according to Moore’s theory; for two-stage setup, obtained results appear consistent and qualitatively according with experimental tests and, unlike the single stage analysis, only fast rotation waves were found.

Numerical Investigation of VSVs Mal-Schedule Effects in a Three-Stage Axial Compressor

2014 ◽  
Author(s):  
Yan-Ling Li ◽  
Abdulnaser Sayma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Numerical Study ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Multi Stage ◽  
Flow Features ◽  
Grid Points ◽  
Stage Matching ◽  
Outflow Boundary

Variable Stator Vanes (VSVs) are commonly used in multi-stage axial compressors for stage matching at part load operations and during start up. Improper VSVs settings or malfunction of the controlling actuator system can lead to compressor instabilities including rotating stall and surge. It is important to be able to predict the aerodynamic behaviour of compressors in such events to either produce tolerant designs or incorporate diagnosis and recovery systems. This paper presents a numerical study of a compressor operating near the stall boundary for a mal-scheduled VSVs case. A high-speed three-stage axial compressor with Inlet Guide Vanes (IGV) is used in the investigation because of its relative simplicity and availability of geometry and aerodynamic data. A 3D RANS viscous unsteady time-accurate flow solver was used to perform the full annulus simulation with a downstream variable nozzle to control outflow boundary conditions. The unstructured mesh contained about 25 million grid points and the simulation was performed on a high performance computing cluster for many engine rotations. Rotating stall with one single cell covering several passages in all three rotors was predicted which propagated at approximately half of the shaft speed. Full analysis of the flow features is presented in the paper.

Delayed Detached Eddy Simulation of Rotating Stall for a Full Annulus Transonic Axial Compressor Stage

2016 ◽  
Author(s):  
Jiaye Gan ◽  
Hong-Sik Im ◽  
Ge-Cheng Zha
Keyword(s):  
Stokes Equations ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Stall Inception ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Stall Cells

This paper solves the filtered Navier-Stokes equations to simulate stall inception of NASA compressor transonic Stage 35 with delayed detached eddy simulation (DDES). A low diffusion E-CUSP Riemann solver with a 3rd order MUSCL scheme for the inviscid fluxes and a 2nd order central differencing for the viscous terms are employed. A full annulus of the rotor-stator stage is simulated with an interpolation sliding boundary condition (BC) to resolve the rotor-stator interaction. The tip clearance is fully gridded to accurately resolve tip vortices and their effect on stall inception. The DDES results show that the stall inception of Stage 35 is initialized by a weak harmonic disturbance with the length scales of the full annulus and grows rapidly with two emerging spike like disturbance. The two spike disturbances propagate in counter rotational direction with about 42% of rotor speed. The spike stall cells cover about 6 blades. They lead to two stall cells grown circumferentially and inwardly.

Experimental Investigation of Rotating Instabilities in a Two-Stage Centrifugal Compressor With Vaneless Diffuser

2001 ◽  
Author(s):  
Vladimir V. Golubev
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Compressor ◽  
Pressure Fluctuations ◽  
Rotating Stall ◽  
Sensitive Area ◽  
Flow Conditions ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Two Stage ◽  
Multi Stage

Abstract This paper examines unsteady response of an experimental two-stage centrifugal compressor with vaneless diffusers. A thorough investigation of pressure fluctuations along the compressor channel is carried out in order to examine the onset of unstable flow conditions. Rotating stall structures are localized, with special attention paid to identifying the most sensitive area of the multi-stage compressor channel which may serve as a precursor to unstable compressor operation. It is shown that both stages may develop rotating stall structures simultaneously, however the 2nd stage tends to destabilize first and reveals higher magnitudes of the unsteady response.

Post-Stall Behaviour of a Multi-Stage High Speed Compressor at Off-Design Conditions

2018 ◽  
Author(s):  
Fanzhou Zhao ◽  
John Dodds ◽  
Mehdi Vahdati
Keyword(s):  
High Speed ◽  
Transient Flow ◽  
Axisymmetric Flow ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Experimental Measurements ◽  
Cfd Simulations ◽  
Blade Loading ◽  
Transient Behaviour ◽  
Multi Stage

Stall followed by surge in a high speed compressor can lead to violent disruption of flow, damage to the blade structures and, eventually, engine shutdown. A knowledge of unsteady blade loading during such events is crucial in determining the aeroelastic stability of blade structures, experimental test of such events is however significantly limited by the potential risk and cost associated. Numerical modelling, such as unsteady CFD simulations, can provide a more informative understanding of the flow field and blade forcing during post-stall events, however very limited publications, particularly concerning multi-stage high speed compressors, can be found. The aim of this paper is to demonstrate the possibility of using CFD for modelling full-span rotating stall and surge in a multi-stage high speed compressor, and, where possible, validate the results against experimental measurements. The paper presents an investigation into the onset and transient behaviour of rotating stall and surge in an 8-stage high speed axial compressor at off-design conditions, based on 3D URANS computations, with the ultimate future goal being aeroelastic modelling of blade forcing and response during such events. By assembling the compressor with a small and a large exit plenum volume respectively, a full-span rotating stall and a deep surge were modelled. Transient flow solutions obtained from numerical simulations showed trends matching with experimental measurements. Some insights are gained as to the onset, propagation and merging of stall cells during the development of compressor stall and surge. It is shown that surge is initiated as a result of an increase in the size of the rotating stall disturbance, which grows circumferentially to occupy the full circumference resulting in an axisymmetric flow reversal.

Analysis of Dynamic Couplings in Two-Stage Geared Systems

1999 ◽  
Author(s):  
J. P. Raclot ◽  
P. Velex
Keyword(s):  
Dynamic Behavior ◽  
Gear Tooth ◽  
Equations Of Motion ◽  
Broad Band ◽  
Two Stage ◽  
Multi Stage ◽  
Speed Reducer ◽  
Definition Of ◽  
Parametric And External Excitations ◽  
Local Stiffness

Abstract A modular model for the simulation of the dynamic behavior of multi-stage spur and helical gears is presented. It is mostly based on shaft finite elements combined with some specific gear elements which account for torsional-flexural-axial couplings, parametric and external excitations. Each tooth contact on theoretical base planes is assimilated to a line contact and discretized in accordance with the contact line evolutions when pinions and gears are rotating. A local stiffness and a normal deviation which represent gear tooth elasticity and tooth shape modifications or/and errors are associated with each cell of the time-dependent grid. Seeking particular stable solutions only, the equations of motion are linearized and solved by using a specific spectral method which has been adapted to parametrically excited systems submitted to broad band parametric and external excitations. Numerical simulations (dynamic transmission errors and displacements) have been performed for two different two-stage geared trains, i. e., a dual speed reducer (two pinion-gear pairs) and a dual mesh reverse idler (3 gears). The role and the definition of profile modifications (short/long reliefs), the contributions of pitch errors and the influence of the mesh relative orientation on the system dynamic behavior are examined. Finally, the nature and the intensity of the inter-mesh couplings in a double stage geared unit are discussed.

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