EltaweelA122013D.pdf (5.6 MB)
Numerical Investigation of Tandem-Cylinder Aerodynamic Noise and Its Control with Application to Airframe Noise
thesis
posted on 2013-12-09, 00:00 authored by Ahmed EltaweelPrediction and reduction of airframe noise are critically important to the development of quieter civil transport aircraft. The key to noise reduction is a full understanding of the underlying noise source mechanisms. In this study, tandem cylinders in cross-flow as an idealization of a complex aircraft landing gear configuration are considered to investigate the noise generation and its reduction by flow control using single dielectric barrier discharge plasma actuators. The flow over tandem cylinders at Re_D= 22,000 with and without plasma actuation is computed using large-eddy simulation. The plasma effect is modeled as a body force obtained from a semi-empirical model. The flow statistics and surface pressure frequency spectra show excellent agreement with previous experimental measurements. For acoustic calculations, a boundary-element method is implemented to solve the convected Lighthill equation. The solution method is validated in a number of benchmark problems including flows over a cylinder, a rod-airfoil configuration, and a sphere. With validated flow field and acoustic solver, acoustic analysis is performed for the tandem-cylinder configuration to extend the experimental results and understand the mechanisms of noise generation and its control. Without flow control, the acoustic field is dominated by the interaction between the downstream cylinder and the upstream wake. Through suppression of vortex shedding from the upstream cylinder, the interaction noise is reduced drastically by the plasma flow control, and the vortex-shedding noise from the downstream cylinder becomes equally important. At a free-stream Mach number of 0.2, the peak sound pressure level is reduced by approximately 16 dB. This suggests the viability of plasma actuation for active control of airframe noise. The numerical investigation is extended to the noise from a realistic landing gear experimental model. Coarse-mesh computations are performed, and preliminary results are discussed with a view of future directions.
History
Date Modified
2017-06-05Research Director(s)
Prof. Meng WangCommittee Members
Dr. Sadegh Dabiri Prof. Gretar Tryggvason Prof. Scott C. MorrisDegree
- Master of Science in Mechanical Engineering
Degree Level
- Doctoral Dissertation
Language
- English
Alternate Identifier
etd-12092013-093723Publisher
University of Notre DameProgram Name
- Aerospace and Mechanical Engineering
Usage metrics
Categories
No categories selectedKeywords
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC