Date of Award

Winter 2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Aerospace Engineering

Committee Director

Osama A. Kandil

Committee Member

Oktay Baysal

Committee Member

Chuh Mei

Committee Member

Duc T. Nguyen

Abstract

Supersonic travel over land would be a reality if new aircraft are designed such that they produce quieter ground sonic booms, no louder than 0.3 psf according to the FAA requirement. An attempt is made to address the challenging goal of predicting the sonic boom focusing effects and mitigate the sonic boom ground over pressure for delta wing geometry.

Sonic boom focusing is fundamentally a nonlinear phenomenon and can be predicted by numerically solving the nonlinear Tricomi equation. The conservative time domain scheme is developed to carry out the sonic boom focusing or super boom studies. The computational scheme is a type differencing scheme and is solved using a time-domain scheme, which is called a conservative type difference solution. The finite volume method is used on a structured grid topology. A number of input signals Concorde wave, symmetric and ax symmetric ramp, flat top and typical N wave type are simulated for sonic boom focusing prediction. A parametric study is launched in order to investigate the effects of several key parameters that affect the magnitude of shock wave amplification and location of surface of amplification or "caustics surface." A parametric studies includes the effects of longitudinal and lateral boundaries, footprint and initial shock strength of incoming wave and type of input signal on sonic boom focusing.

Another very important aspect to be looked at is the mitigation strategies of sonic boom ground signature. It has been decided that aerodynamic reshaping and geometrical optimization are the main goals for mitigating the ground signal up to the acceptance level of FAA. Biconvex delta wing geometry with a chord length of 60 ft and maximum thickness ratio of 5% of the chord is used as a base line model to carry out the fundamental research focus. The wing is flying at an altitude 40,000 ft with a Mach number of 2.0. Boom mitigation work is focused on investigating the effects of wing thickness ratio, wing camber ratio, wing nose angle and dihedral angle on mitigating the sonic-boom ground signature.

Optimal shape design for low sonic boom ground signature and least degradation of aerodynamic performance are the main goals of the present work. Response surface methodology is used for carrying out wing shape optimization. Far-field computations are carried out to predict the sonic boom signature on the ground using the full-potential code and the Thomas ray code.

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DOI

10.25777/hx9q-ja15

ISBN

9780549329459

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