Abstract
This paper presents an experimental investigation into the effects of turbulence ingestion on the aerodynamic noise characteristics of rotor blades in edgewise flight. A small-scaled, two-bladed rotor was used in the study. The test utilised two turbulence-generating grids, to generate turbulence inflows with different characteristics, and to compare them to the baseline configuration of the laminar inflow. The experiments were set at forwarding edgewise flight configuration, with freestream inflow velocity ranging from 10 m/s to 22 m/s. Simultaneous measurements of far-field acoustic pressure and load were conducted, along with a separate flow measurement using particle image velocimetry. The acoustic spectra demonstrated a larger contribution to the tonal noise radiation at blade passing frequency, and to the broadband noise radiation at the mid-frequency domain, due to turbulence ingestion. However, the broadband responses in the high-frequency domain were comparable between the tested laminar and turbulence inflow cases, with similar broadband humps featuring in the acoustic spectra. The directivity patterns of the overall sound pressure level showed that the noise radiation was lowest near the plane of rotation, and highest downstream. Turbulence ingestion effects could also be seen in the elevated noise levels throughout the observation positions for the grid inflow cases, particularly at larger advance ratios.
Original language | English |
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Article number | 502 |
Number of pages | 18 |
Journal | Aerospace |
Volume | 10 |
Issue number | 6 |
DOIs | |
Publication status | Published - 25 May 2023 |
Bibliographical note
Funding Information:The first author would like to acknowledge the financial support of Majlis Amanah Rakyat Malaysia. The second author would like to acknowledge EPSRC (Engineering and Physical Sciences Research Council) via Grant No. EP/S013024/1. The first and third authors would like to acknowledge the Horizon 2020 research and innovation programme under grant agreement number 882842 (SilentProp project). All authors would like to thank Luke Bowen for his assistance in building and analysing the grid.
Funding Information:
This research was funded by The European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement 82842—SilentProp project) and the Engineering and Physical Sciences Research Council (EPSRC) under grant reference number EP/S013024/1.
Publisher Copyright:
© 2023 by the authors.
Keywords
- Rotor Noise
- Turbulence Ingestion
- Experimental Aeroacoustics
- Edgewise Flight
- PIV Measurement