Towards counter-rotating open rotor noise reduction via radiation efficiency considerations

Horváth, Csaba and Fenyvesi, Bence and Kocsis, Bálint and Quaglia, Michael and Moreau, Stéphane (2019) Towards counter-rotating open rotor noise reduction via radiation efficiency considerations. In: 25th AIAA/CEAS Aeroacoustics Conference, 2019.05.20-2019.05.24, DELFT, NETHERLANDS.

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This study approaches the question of counter-rotating open rotor engine noise levels from a yet unexplored perspective, examining the radiation efficiency properties of unducted turbomachinery acoustic modes in order to provide design guidelines that mitigate the radiation of sound without the need for shielding. Two design guidelines, based purely on the radiation efficiency properties, can be defined for the reduction of blade passing frequency and interaction tone noise levels of counter-rotating open rotors operating under low speed design conditions typical of take-off and approach. The two proposed design guidelines state that a large and equal number of blades should be used on the forward and aft rotors. The first design guideline adheres well with the current practice of using a large number of blades, supporting the current design practice from a new perspective. The second design guideline, on the other hand, might at first glance seem counterintuitive with regard to current design trends and guidelines. An investigation of two 12/10 and 12/12 blade number configurations is presented herein, the results of which support the theory, with reductions of up to 10dB in OASPL for the 12/12 configuration for certain viewing angles, with the 12/12 configuration being quieter than the 12/10 configuration in almost all examined directions. The paper provides a description of the theory behind the design guidelines, supporting the findings with simulation data and independently attained experimental measurement data

Item Type: Conference or Workshop Item (Paper)
Additional Information: This paper has been supported by the Hungarian National Research, Development and Innovation Centre under contracts No. K 119943, and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences, and by the ÚNKP-18-4 New National Excellence Program of the Ministry of Human Capacities. The research reported in this paper was supported by the Higher Education Excellence Program of the Ministry of Human Capacities in the frame of Water sciences & Disaster Prevention research area of BME (BME FIKP-VÍZ). Regarding the simulations, we wish to acknowledge the technical support from Ecole Centrale de Lyon on Turb’Flow and Compute Canada and the RQCHP (Re ́seau Que ́be ́cois de Calcul Haute Performance) for providing the necessary computational resources. We wish to acknowledge the financial support of Snecma-Safran Group. Regarding the measurements, the research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Clean Sky Joint Technology Initiative under grant agreement no. [278419]. The authors would like to acknowledge the work of the WENEMOR consortium: Trinity College Dublin, Ireland (Coordinator), Pininfarina S.P.A., Italy, Teknosud S.R.L, Italy, MicrodB, France, Universita Politecnica delle Marche, Italy, Paragon SA, Greece, Eurotech, Italy and the ITD: Leonardo S.p.A.
Subjects: T Technology / alkalmazott, műszaki tudományok > TJ Mechanical engineering and machinery / gépészmérnöki tudományok
Depositing User: MTMT SWORD
Date Deposited: 24 Sep 2019 06:14
Last Modified: 25 Sep 2019 09:20

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