Thesis supervisor: Csaba Horváth
Location of studies (in Hungarian): BME Department of Fluid Mechanics Abbreviation of location of studies: ÁT
Description of the research topic:
a.) Background:
Microphone array measurements and beamforming methods are evolving at a very rapid pace. In recent years, the literature has reported on the development of countless methods, and the utilization of the technology in many new applications. One subset of microphone array measurements and beamforming methods deals with the localization of rotating noise sources. There are currently five research groups in the world developing these methods on a serious level, including the Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Department of Fluid Mechanics, Turbomachinery Research Group. The prospective supervisor is one of the leaders of this research group and has already made several developments in this area [1-5].
Turbomachinery noise is generated by many complex noise sources and results in a complicated sound field in the listener’s position. The literature has dealt with these noise sources on a deeper level for more than 50 years, and interest and development in this topic is continuous and rapid. This development is mainly due to the continuous development and frequent application of turbomachinery technology. Currently, the development of multi-rotor aircrafts (e.g., UAV, UAM, and drone) has provided a renewed momentum to the research.
There are currently very few studies in the multi-rotor aircraft literature that investigate the noise sources of the propulsion systems using microphone array measurements and beamforming methods. However, the development of quiet multi-rotor aircrafts is a popular and rapidly growing area of research. The number of beamforming studies can be traced back to the shortcomings of the currently available methods. Beamforming methods for locating rotating noise sources could be further developed in a number of ways, making them suitable for the noise source localization of all types of multi-rotor aircraft noise sources.
b.) Aim of the research:
The aim of the research is to develop and apply beamforming methods for the localization of rotating noise sources in the investigation of quiet multi-rotor aircraft configurations and operating conditions. The main goal is to develop methods for the segmented examination of rotating noise source trajectories and to define quiet multi-rotor aircraft design guidelines for developers. The results will provide insight into multi-rotor aircraft noise sources and provide methods and guidance for engineers designing quiet turbomachinery.
c.) Assignments, their main elements, necessary time:
1st year: Literature review: Rotating noise sources (2 months), beamforming methods and beamforming methods for localizing rotating noise sources (3 months), Python programming language (2), Acoular open source beamforming program (2), and multi-rotor aircraft noise (3 months).
Testing of the segmented ROSI beamforming method using a rotating noise source test bench (rotating speakers) measurements and/or simulations (numerical rotating point source) as a function of viewing angle, rotor speed, and blade number (6 months). Further development of the Segmented ROSI beamforming method for the localization of rotating broadband noise sources associated with specific segments of the rotor trajectory, which is to be achieved by combining the Segmented ROSI method and the Double Filter beamforming method (6 months).
2nd year: Further development of the Segmented ROSI beamforming method for frequency domain applicability (4 months). Execution of multi-rotor test bench measurements as a function of viewing angle and rotor speed (4 months). Investigation of the beamforming results of the noise sources (4 months).
3rd year: Multi-rotor test bench measurements as a function of blade number and distance between rotors (6 months). Investigation of the beamforming results of the noise sources (6 months).
4th year: Preparation of the PhD dissertation (12 months).
d.) Required equipment:
The tools and equipment necessary for the investigations are partly available and will be further developed with the support of NKFI K funding.
e.) Expected scientific results:
The novel elements of the research that will lead to thesis-worthy results: a) The localization of the noise sources of multi-rotor propulsion systems and the investigation of their change as a function of configuration and operating condition. b) Further development of beamforming methods for the localization of rotating noise sources. c) Determination of quiet multi-rotor configurations and operating conditions.
f.) References:
[1] Cs. Horváth, E. Envia, G.G. Podboy. “Limitations of phased array beamforming in open rotor noise source imaging.” AIAA Journal, Vol. 52, No. 8, 1810-1817, 2014.
[2] K. Tokaji, B. Soós, and Cs. Horváth, “Beamforming method for extracting the broadband noise sources of counter-rotating open rotors”, AIAA Journal, Vol. 58, No. 7, 3028-3039, 2020.
[3] Cs. Horváth, and B. Kocsis, “Towards a Doppler Effect based beamforming method for rotating coherent noise sources”, In 7th Berlin Beamforming Conference, BeBeC-2018-D27, 2018.
[4] H. Zhang, B. Kocsis, and Cs. Horváth, “Further development of the ROSI beamforming method for the investigation of turbomachinery investigated at an angle”, In 8th Berlin Beamforming Conference, BeBeC-2020-D13, 2020.
[5] H. Zhang, B. Kocsis, and Cs. Horváth, “Segmented ROSI method: Beamforming method for investigating turbomachinery noise sources along segmented trajectories”, NOISE CONTROL ENGINEERING JOURNAL 70 : 1 pp. 62-76. , 15 p. (2022).
Required language skills: English Number of students who can be accepted: 1
Deadline for application: 2024-10-15
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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