The FLORA (FLOw control in RAdial compressor) project aims at promoting the development of the next generation of aeronautical engines (weight reduction, increased efficiency and stability range) to reduce environmental impact of air transport (reducing emissions of CO2, NOx and noise impact). In such a context, the compressors are major components because they determine the fuel consumption, the stability range and the acceleration ability of the entire engine. The enhancement of an engine operability involves increasing the compressor surge margin which is still an open challenge. Thus FLORA project main goal is to contribute to extending the aeronautics centrifugal compressor operating range to more efficient operating zone.
From an aerodynamic point of view, that requires a better understanding of phenomena which limit the stability range and to develop strategies in order to widen it while keeping (even increasing) the performance at nominal operating condition.
FLORA project has two main objectives:
• First, it proposes to achieve a comprehensive understanding of the transient behaviour of the radial compressor delivered by Safran Helicopter Engines through a precise characterization of the instabilities which develop at various rotation speeds and at different Inlet Guide Vanes stagger angles. Detailed experimental investigations are planned providing an improved and time-resolved description of the path to surge (including unsteady pressure and LDV measurements).
• Then, it proposes to apply passive flow control strategies in order to push back the compressor surge line towards low mass flow which will consequently enhance the compressor stability, hence the engine operability. The project particularly aims at evaluating the benefits from the boundary layer aspiration in radial geometries in terms of performance (gain in pressure ratio and efficiency) and surge margin.
Besides experiments, calculations will help for the understanding of the internal flow structures which develop from stable operating points up to surge. Numerous (U)RANS and LES simulations will be used to get an in-depth comprehension of the impact of the flow control on the internal flow.
This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement N° 820099.
