Mahmoud Hayajnh

(Advisor: Prof. Prasad)

will propose a doctoral thesis entitled,

The Development of Parametric Rotor Control Equivalent Turbulence Input (RCETI) Models

On

Monday, July 10 at 9:00 a.m.

Via Microsoft Teams: URL Link

Abstract

Accurate modeling of turbulence effects on the aircraft dynamics is crucial for ensuring safe and efficient operations. Control Equivalent Turbulence Input (CETI) models have been developed as an approach to simulate the response of rotorcraft to atmospheric turbulence. These models produce control inputs that, when integrated into the control channels, result in vehicle responses that are stochastically similar to vehicle responses due to turbulence. However, these models are typically tailored to specific vehicles, making them less transferable to other vehicle types and configurations. To address this limitation, this research introduces the concept of Rotor Control Equivalent Turbulence Input (RCETI) models. By utilizing hub-loads as outputs and swashplate deflections as inputs, these models capture the impact of turbulence on rotor response, enabling for a direct and efficient assessment of vehicle performance in turbulent conditions. The primary objective of this thesis is to develop a methodology for the development of parametric RCETI models, which provide a more generalized approach to rotorcraft turbulence simulation. Unlike vehicle-specific CETI models, RCETI models are scalable and adaptable, allowing for their application to various rotorcraft configurations.  To demonstrate the feasibility and effectiveness of the RCETI approach, a proof of concept is conducted using Linear Time-Invariant (LTI) approximations derived from a comprehensive nonlinear helicopter model implemented in FLIGHTLAB. The LTI approximations accurately represent the coupled dynamics of the body, rotor, and inflow, providing a reliable foundation for RCETI model development. The Dryden turbulence model is employed to determine the Power Spectral Density (PSD) of turbulence. The analysis focuses on collective, longitudinal, and lateral inputs, considering rotor parameters as variables of the RCETI models. The scalability of these parametric models is demonstrated by extrapolating them to parameter values that were not utilized during the development phase. Proposed work includes enhancing the RCETI models by replacing the Dryden model with more representative turbulence models for urban environments, as well as replacing the current hub-fixed sampling technique with more precise blade-element sampling. Furthermore, the investigation will explore the impact of additional rotor parameters on the RCETI models and their scalability. Moreover, the scope of the research will be extended to encompass the application of RCETI models to multi-rotor vehicles.

Committee

• Prof. J.V.R. Prasad – School of Aerospace Engineering (advisor)
• Prof. Marilyn J. Smith – School of Aerospace Engineering
• Prof. Lakshmi N. Sankar – School of Aerospace Engineering