MAGPI - Main Annulus Gas Path Interactions
Overview
Background & policy context:
In a modern aero engine, up to 20% of the main annulus flow is bled off to perform cooling and sealing functions. The vicinity of these bleed ports and flow sinks is characterised by complex unsteady swirling flows, which are not fully understood. Even the most up-to-date numerical tools have difficulties predicting the behaviour of the secondary flow system when interacting with the main annulus.
The project addressed interactions between main gas path and secondary flow systems in commercial gas turbines in response to Research Activity AERO-2005-1.3.1.2a Concepts and technologies for improving engine thermal efficiency and reducing secondary air losses.
Objectives:
Technical Challenges:
- Understanding of interactions between annulus gas flow and air system (unsteady, 3-dimensional, interaction with blades).
Objectives:
- Reduce turbine rim sealing air mass flow.
- Improve turbine efficiency / minimise flow distortions caused by sealing air e.g. by better geometry.
- Improve CFD tools for complex interactions between air system and main gas path (turbines and compressor).
Expected Benefits:
- SFC, component life, reliability, development cost, better tools.
The targeted outcome contributed to the ACARE goal of reduced CO2 emissions via reduced fuel burn of 2% to improve the environment and strengthening the competitiveness of European gas turbine manufacturers.
Methodology:
Experiments were planned on turbine disc rim and compressor manifold cavity heat transfer, hot gas ingestion, and spoiling effects of cooling air flow and their impact on turbine and compressor performance, as well as a reduction of secondary air losses.
The experimental data was used for better understanding of the complex flow phenomena and improvements of platform and cavity design. Furthermore, the industrial partners will validate their design tools with these test data and improve their prediction capability of secondary flow systems when interacting with the main gas path. The expected results are a reduction of cooling and sealing airflow rates, improvements of the turbine and compressor efficiency and increase of the safety margin of the engine components by better cooling.
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