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Development of an innovative active flow control system for CROR powerplant noise reduction through pylon wake mitigation

Bury, Yannick and Bordron, Alban and Belloc, Hervé and Prat, Damien Development of an innovative active flow control system for CROR powerplant noise reduction through pylon wake mitigation. (2015) In: 50th 3AF International Conference on Applied Aerodynamics, 30 March 2015 - 1 April 2015 (Toulouse, France).

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Given the increasingly stringent regulations governing the air transport sector, driven by environmental and economic concerns, efforts to reduce air traffic fuel consumption and to limit pollutant and noise emissions encourage both aircraft and powerplant manufacturers to develop innovative solutions for future aircrafts. In this context, Counter Rotating Open Rotor (CROR) propeller technologies are appearing as a promising alternative solution to Ultra High Bypass Ratio (UHBR) engines. However the promotion of this not yet fully mature technology, although it was initiated in the early 80’s, raises numerous issues and imposes to address significant scientific and technological challenges. Amongst these challenges, the interaction of the wake of the CROR engine pylon with the counter rotating blades, positioned downstream of the pylon (pusher configuration), promote strong total pressure fluctuations on the powerplant structure. The latter are responsible for both airframe noise and vibrations that penalize aircraft certification. ‘Erasing’ the pylon wake such as to recover a strictly uniform flow upstream of the rotating blades would suppress this major source of airframe noise and vibrations. It therefore appears as a promising flow control strategy for the certification of CROR propeller-equipped aircrafts. The current study is put forward in that context. It is part of the ACcTIOM project, a collaborative research project led in partnership with Airbus and Aéroconseil and funded by the European Commission through the Cleansky/SFWA (Smart Fixed Wing Aircraft) Demonstrator program. It first aims to design an active flow control system dedicated to the reduction of noise emission through the pylon wake mitigation. Second, it aims to develop an advanced experimental methodology, based on vibration-controlled stereoscopic Particle Image Velocimetry (3C-PIV), able to be flight-operated and that will serve the validation of the above mentioned active flow control system when operated on the Flying Test Bench. In this paper we focus on the development and the validation of the active flow control system, to be integrated in the aft part of the CROR propeller pylon. This flow control system is based on a boundary layer scooping/blowing strategy. The optimization process of the flow control system, based on 2D and 3D RANS computations, has allowed designing the wind tunnel (WT) model and pre defining the flow control parameters - scooping and blowing mass flow rates- to apply such as to mitigate the pylon wake. By experimentally varying these parameters, and taking advantage of the WT experiment results, based on pressure coefficient distribution along the WT model profile, transverse profiles of total pressure at various streamwise and spanwise positions in the wake of the pylon and on 3C-PIV transverse-plane measurements at various streamwise positions, an exhaustive cartography of the flow control system efficiency was determined. It allows identifying nominal operating points, where the optimization criterion is satisfied. It also highlights the robustness of the embedded flow control system in mitigating the wake of the pylon.

Item Type:Conference or Workshop Item (Paper)
Audience (conference):International conference proceedings
Uncontrolled Keywords:
Institution:Other partners > AKKA Technologies (FRANCE)
Other partners > Airbus (FRANCE)
Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE)
Laboratory name:
Deposited On:22 Jul 2015 15:15

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