Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581486
Title: High-order computations on aerofoil-gust interaction noise and the effects of wavy leading edges
Author: Lau, Alex Siu Hong
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2012
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Abstract:
High-order accurate numerical simulations are performed to investigate the effects of wavy leading edges on aerofoil gust interaction (AGI) noise. The present study is based on periodic velocity dis-turbances predominantly in streamwise (x-) and vertical (y-) directions that are mainly responsible for the surface pressure fluctuation of an aerofoil. The perturbed velocity components of the present gust model do not vary in the spanwise (z-) direction. In general, the present results show that wavy leading edges lead to reduced AGI noise. Under the current incident gusts, it is found that the ratio of the wavy leading-edge peak-to-peak amplitude (LEA) to the longitudinal wavelength of the incident gust (λg) is the most important factor for the reduction of AGI noise. It is observed that AGI noise reduces with increasing LEA/λg, and significant noise reduction can be achieved for LEA/λg≥0.3. The present results also suggest that any two different cases with the same LEA/λg lead to a strong similarity in their profiles of noise reduction relative to the straight leading-edge case. The wavelength of wavy leading edges (LEW), however, shows minor influence on the reduction of AGI noise under the present gust profiles used. Nevertheless, the present results show that a meaningful improvement in noise reduction may be achieved when 1.06LEW/λg 61.5. In addition, it is found that the beneficial effects of wavy leading edges are maintained for various angles of attack and aerofoil thicknesses. Also, wavy leading edges remain effective in reducing AGI noise for gust profiles containing multiple frequency components. It is discovered in the current research that wavy leading edges result in in-coherent response time to the incident gust across the span, which causes a decreased level of surface pressure fluctuations, hence a reduced level of AGI noise.
Supervisor: Kim, Jae Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.581486  DOI: Not available
Keywords: TL Motor vehicles. Aeronautics. Astronautics
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