Numerical Investigation of Tandem-Cylinder Aerodynamic Noise and Its Control with Application to Airframe Noise

Doctoral Dissertation

Abstract

Prediction 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.

Attributes

Attribute NameValues
URN
  • etd-12092013-093723

Author Ahmed Eltaweel
Advisor Prof. Meng Wang
Contributor Prof. Meng Wang, Committee Chair
Contributor Dr. Sadegh Dabiri, Committee Member
Contributor Prof. Gretar Tryggvason, Committee Member
Contributor Prof. Flint O. Thomas, Committee Co-Chair
Contributor Prof. Scott C. Morris, Committee Member
Degree Level Doctoral Dissertation
Degree Discipline Aerospace and Mechanical Engineering
Degree Name PhD
Defense Date
  • 2013-12-05

Submission Date 2013-12-09
Country
  • United States of America

Subject
  • Hybrid Acoustic Approach

  • Plasma Flow Control

  • Landing Gear Noise

  • Active Flow and Noise Control

  • Tandem Cylinders

  • Rod-Airfoil Wake Interaction

Publisher
  • University of Notre Dame

Language
  • English

Record Visibility Public
Content License
  • All rights reserved

Departments and Units

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