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Advanced Civil Core Compressor Aerodynamics

Cel

The aim of the project is to investigate two areas of civil core compressor aerodynamics which will result in significant improvements in both efficiency and operating range: mastery of tip clearance effects in the design process; active suppression of the flow instabilities which lead to surge and stall.
The low-speed multi-stage experiments have revealed that the use of cantilevered stators, instead of shrouded, has no apparent detrimental effect on compressor performance. The influence of each stator technology on the local flow features has also been identified using the detailed measurements. The capability of 3D Laser Anemometry to map complex 3D unsteady viscous flows has been demonstrated and there are therefore some good prospects for the intensive use of these measurement techniques in real high-speed multi-stage turbomachinery. Significant scientific benefits are expected from the exploitation of the innovative annular cascade experiment which has been successfully conducted.

On the theoretical side, the throughflow approach (first level model) has shown good predictive capabilities on low speed test-cases and the tip clearance model will be implemented by the partners who still heavily rely on meridional tools. As regards the 3D Navier-Stokes conputations, the k-epsilon turbulence model has proved a reasonable accuracy and robustness for the simulation of clearance flows. This important result has usefully guided the code developments conducted by the partners outside the programme.

Four high speed compressors have been tested in a consistent manner, with a good definition of high response instrumentation, and their stall inception performance analysed. Stall inception data from each compressor has been formed into a single database. The data has been used to validate a computer model of stall inception. Conclusions have also been drawn on the possibility of applying active control of stall/surge to high speed compressors.

A surprising range of stall inception behaviour has been observed in the experiments. Under the current programme both pips and modes have been seen to lead to stall, even on the same machine.

Under this programme an existing non-linear two dimensional (axial and circumferential) computer model has been further developed, and has been shown to reflect well the stall inception patterns seen in the experimental part of the programme. The developed model has been used for a brief numerical study of possible active control strategies.

The measurements taken during the programme suggest that active control of stall is technically feasible. At the same time a large number of practical difficulties have been identified concerning the wide range of stalling behaviour observed (both between compressors and between operating points in the same compressor). Whilst it would be possible to device a control system for a specific compressor at a specific operating point, it seems unlikely that such a system would be generally applicable.
The first objective is to understand and master the complex three dimensional viscous flows in the blade clearance regions. This means:

developing and validating theoretical models for tip clearance flows to be included in numerical simulation tools (such as 3D advanced industrial design tool),
increasing experimental data by the development of new experimental facilities and advanced 3D Laser anemometry techniques.

The second objective is to investigate the feasibility of engine-worthy active control of compressor flow instabilities: stall and surge. This is seen primarily as an effort to understand and model the inception of flow instabilities. A database will be formed from experiments on a wide range of high speed compressors, and a complementary modelling effort will be conducted. The experiments include variation of compressor type, aerodynamic duty, Reynolds number, tip clearance and inlet distortion. This approach will determine if the inception of compressor instabilities is similar for a range of compressors and will draw conclusions on the nature of the flow instabilities and the technological feasibility of control action. No such wide-ranging experimental campaign has ever been conducted on the subject. For the resulting data analysis, new techniques must be developed. This line of research will determine to what extent active control of stall and surge in high speed compressors is considered to be a feasible option.

Temat(-y)

Data not available

Zaproszenie do składania wniosków

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System finansowania

CSC - Cost-sharing contracts

Koordynator

Société Nationale d'Études et de Construction de Moteurs d'Aviation (SNECMA)
Wkład UE
Brak danych
Adres
2 boulevard du Général Martial Valin
75724 Paris
Francja

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