Experimental Investigation of the Rotor-Stator Interactions Within a High Speed, Multi-Stage, Axial Compressor: Part 1 — Experimental Facilities and Results

This paper relates to laser anemometry measurements (LDA) conducted in a high speed, three-stage, axial compressor. Particular attention has been paid to the estimation of the measurement accuracy. Three different synchronization procedures have been implemented in order to enhance the exactness of the location in the rotating frame for each situation. Small flat windows mainly provide the optical accesses. But, large curved glasses could also be used, the optical distortions resulting from the surface curvature being corrected with the help of an optical assembly developed for the L2F technique and extended to the LDA technique. Furthermore, in order to avoid interpolation processes when changing the frame of reference, the spatial and time discretizations have been defined in accordance with the numbers of rotor and stator blades. The presented measurements have been performed, at 50% blade height, in the first three inter row sections, the azimuthal exploration covering machine periodicity.

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Stall inception in a multi-stage high speed axial compressor

10.2514/6.1993-2386 ◽

1993 ◽

Cited By ~ 6

Author(s):

DONALD HOYING

Keyword(s):

High Speed ◽

Axial Compressor ◽

Stall Inception ◽

Multi Stage

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Experimental Investigation of the Rotor-Stator Interactions Within a High-Speed, Multi-Stage, Axial Compressor: Part 2 — Modal Analysis of the Interactions

Volume 5: Turbo Expo 2004, Parts A and B ◽

10.1115/gt2004-53778 ◽

2004 ◽

Cited By ~ 10

Author(s):

David Arnaud ◽

Xavier Ottavy ◽

Andre´ Vouillarmet

Keyword(s):

Flow Field ◽

High Speed ◽

Axial Compressor ◽

Rotating Speed ◽

Spatial Harmonics ◽

Multi Stage ◽

Time Period ◽

Original Measurement ◽

Measured Flow ◽

Almost All

The second part of this paper deals with the analysis of the 2D LDA measurements carried out within the high-speed multistage axial compressor CREATE. First the interactions correlations are quantified using the deterministic stresses introduced by Adamczyk. Secondly, a modal decomposition shows that the interactions are characterized by the presence of spatial harmonics (spinning lobes) given by a linear combination of the blades numbers. An original measurement of the rotating speed of the spinning lobes has been carried out allowing to identify almost all the spinning lobes in the first inter row region resulting from the R1-S1 interactions. For the first stage, where the influence of the downstream rows is low, the measured flow field is well reproduced by the model of Tyler and Sofrin. Spatial DFT of the flow field calculated for each time of the compressor time period show that there is a pulsation of the spatial harmonics with the period associated to the minimum elapsed time to recover the same relative positions of the rotor and stator rows.

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Viscous Throughflow Modelling for Multi-Stage Compressor Design

Volume 1: Turbomachinery ◽

10.1115/92-gt-302 ◽

1992 ◽

Cited By ~ 1

Author(s):

M. A. Howard ◽

S. J. Gallimore

Keyword(s):

Shear Force ◽

High Speed ◽

Three Dimensional ◽

Axial Compressor ◽

Design System ◽

Flow Angle ◽

Axial Compressors ◽

Multi Stage ◽

Viscous Shear ◽

Compressor Design

An existing throughflow method for axial compressors, which accounts for the effects of spanwise mixing using a turbulent diffusion model, has been extended to include the viscous shear force on the endwall. The use of a shear force, consistent with a no-slip condition, on the annulus walls in the throughflow calculations allows realistic predictions of the velocity and flow angle profiles near the endwalls. The annulus wall boundary layers are therefore incorporated directly in the throughflow prediction. This eliminates the need for empirical blockage factors or independent annulus boundary layer calculations. The axisymmetric prediction can be further refined by specifying realistic spanwise variations of loss coefficient and deviation to model the three-dimensional endwall effects. The resulting throughflow calculation gives realistic predictions of flow properties across the whole span of a compressor. This is confirmed by comparison with measured data from both low and high speed multi-stage machines. The viscous throughflow method has been incorporated into an axial compressor design system. The method predicts the meridional velocity defects in the endwall region and consequently blading can be designed which allows for the increased incidence, and low dynamic head, near to the annulus walls.

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

Volume 2D: Turbomachinery ◽

10.1115/gt2014-25145 ◽

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.

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Physics of Airfoil Clocking in a High-Speed Axial Compressor

Volume 1: Turbomachinery ◽

10.1115/98-gt-082 ◽

1998 ◽

Cited By ~ 14

Author(s):

Daniel J. Dorney ◽

Om P. Sharma ◽

Karen L. Gundy-Burlet

Keyword(s):

Relative Motion ◽

High Speed ◽

Three Dimensional ◽

Axial Compressor ◽

Unsteady Aerodynamics ◽

Navier Stokes ◽

Jet Engines ◽

Axial Compressors ◽

Multi Stage ◽

Significant Performance

Axial compressors have inherently unsteady flow fields because of relative motion between rotor and stator airfoils. This relative motion leads to viscous and inviscid (potential) interactions between blade rows. As the number of stages increases in a turbomachine, the buildup of convected wakes can lead to progressively more complex wake/wake and wake/airfoil interactions. Variations in the relative circumferential positions of stators or rotors can change these interactions, leading to different unsteady forcing functions on airfoils and different compressor efficiencies. In addition, as the Mach number increases the interaction between blade rows can be intensified due to potential effects. In the current study an unsteady, quasi-three-dimensional Navier-Stokes analysis has been used to investigate the unsteady aerodynamics of stator clocking in a 1-1/2 stage compressor, typical of back stages used in high-pressure compressors of advanced commercial jet engines. The effects of turbulence have been modeled with both algebraic and two-equation models. The results presented include steady and unsteady surface pressures, efficiencies, boundary layer quantities and turbulence quantities. The main contribution of the current work has been to show that airfoil clocking can produce significant performance variations at the Mach numbers associated with an engine operating environment. In addition, the growth of turbulence has been quantified to aid in the development of models for the multi-stage steady analyses used in design systems.

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3D CFD Compressor Map Computation of a Multi-Stage Axial Compressor With Off-Design Adjusted Rotor Geometries

Volume 2C: Turbomachinery ◽

10.1115/gt2016-56745 ◽

2016 ◽

Cited By ~ 1

Author(s):

Christian Janke ◽

Markus Goller ◽

Ivo Martin ◽

Lilia Gaun ◽

Dieter Bestle

Keyword(s):

High Speed ◽

Pressure Ratio ◽

Axial Compressor ◽

Operating Conditions ◽

Tip Clearance ◽

Design Point ◽

Multi Stage ◽

Compressor Design ◽

Compressor Map ◽

Aero Engines

Compressor maps of aero engines show the relation between corrected mass flow, corrected shaft speed, pressure ratio, and efficiency, where different operating conditions of the compressor are represented by different speed lines. These speed lines are an important information for the compressor design process, since they show important operation bounds like surge and choke. Typically, 3D CFD compressor maps are computed with the so called hot geometry given by the aerodynamic design point. But in reality aerofoil shapes change depending on engine speeds and gas loads resulting in twist of the blades and changes of tip clearance. In order to obtain a higher quality compressor map, all these effects must be taken into account. Therefore, a process is utilized which uses coupled CFD and FE analyses to account for load adjusted geometries aside the design point. For transformation of FE results into the CFD model a cold-to-hot blade morphing technique is used. The studies are performed for a 4.5 stage high speed axial compressor, where effects of varying tip clearance and geometry deformation are considered separately from each other. Finally, their combined effects are studied.

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

Volume 2A: Turbomachinery ◽

10.1115/gt2018-75283 ◽

2018 ◽

Cited By ~ 1

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.

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