Date of Award

Spring 5-4-2026

Access Type

Dissertation - Open Access

Degree Name

Doctor of Philosophy in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Ebenezer Gnanamanickam

Committee Chair Email

gnanamae@erau.edu

Committee Advisor

Ebenezer Gnanamanickam

Committee Advisor Email

gnanamae@erau.edu

First Committee Member

J. Gordon Leishman

First Committee Member Email

leishmaj@erau.edu

Second Committee Member

Anastasios S. Lyrintzis

Second Committee Member Email

lyrintzi@erau.edu

Third Committee Member

Sandra K.S. Boetcher

Third Committee Member Email

Sandra.Boetcher@erau.edu

College Dean

James W. Gregory

Abstract

Shipboard helicopter operations occur within a highly unsteady environment referred to as the dynamic interface (DI), encompassing the coupled effects of the ship airwake, rotor wake, flight dynamics, and pilot response. A central aspect of the DI is the aerodynamic interaction between the ship airwake and the rotor wake, which degrades handling qualities and increases pilot workload, yet the underlying mechanisms governing ship-rotor coupling remain insufficiently understood. The ship-rotor aerodynamic coupling was examined using two canonical ship geometries, the NATO-GD and SFS2, together with a controlled experimental framework, the airflow-and-blade-frequency (ABF) system, which independently varied wake momentum flux and unsteady forcing frequency. Particle image velocimetry measurements were used to characterize both isolated and coupled flow fields across a range of operating conditions. Mean-flow superposition and spectral analyses were employed to assess the validity of linear superposition in modeling the DI. In addition, a reduced-order model based on proper orthogonal decomposition decomposed the flow into time-dependent linear and nonlinear components and identified regions of constructive and destructive interference. The results showed that aerodynamic coupling produced a significant increase in turbulent kinetic energy over an extended region of the flight deck, driven by rotor-induced feedback into the ship airwake, particularly within frequency ranges associated with elevated pilot workload. For the NATO-GD configuration, the coupling was strongly nonlinear and could not be represented by linear superposition, with elevated energy levels persisting across all ABF operating conditions. The SFS2 geometry exhibited weaker coupling, with flow features more closely approximated by linear behavior. These findings demonstrated that the degree of nonlinear coupling was geometry-dependent and must be accounted for in aerodynamic models of the DI, thereby providing a physics-based foundation for improving shipboard flight simulators through more realistic representations of the unsteady disturbance environment encountered in the DI.

Additional Files
Mazzilli Form GS9 Acceptance.pdf (520 kB)
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