Noise minimal & green trajectory and flight profile optimization for helicopters

Yücekayalı, Ard
The main aim of this study is to provide a multi-disciplinary optimization and track environment to generate acoustic optimal trajectories through waypoints that ensures the rotorcraft of interest can follow at practical effort, safety, fuel consumption and speed. Rotorcraft noise annoyance remains as a challenge to solve complex, three dimensional and coupled rotary wing aerodynamics, aeroacoustics and flight dynamics interactively. Two essential paths can be acknowledged in order to reduce annoyance. One is the more sophisticated option, optimized new rotorcraft design, whereas the other option is to benefit from the directivity characteristic of sound and perform trajectory optimization to minimize noise impact at noise sensitive premises. This study focuses on the second yet with consideration of the potential trade-offs between low noise signature and other performance parameters. Eventually, the main aim of this study is to develop a trajectory optimization and track framework for rotorcrafts providing minimal noise, low emission i.e. lower fuel consumption, safe and trackable, in other words “green” flight profiles. In this scope, a Lagrangian CFD solver specialized for rotor/propellers is developed, coupled with rotorcraft mathematical model and an aeroacoustics solver to build a high fidelity, accuracy and resolution rotorcraft comprehensive modeling environment. The developed methodology is validated with wind tunnel, whirl tower test data, PIV results and benchmark commercial tools. The developed comprehensive tool provides free flight trim, high fidelity modeling and analysis capability for conventional and unconventional rotorcraft configurations with unsteady wake dynamics covering blade-vortex, rotor-wake and rotor-rotor interactions. Further in the study, the comprehensive model is extended into a real-time computable simulation model. Then a model predictive control -an optimal control- approach is developed to simultaneously optimize the trajectory and control input to track the generated trajectory. The multi-disciplinary objective function including acoustics, performance, fuel, safety, comfort and mission concerns provides the so called “green” trajectory with reduced noise impact at desired locations. Various simulations were performed to further test the aerodynamic modeling, aeroacoustics analysis and trajectory optimization capabilities of the developed framework. It is concluded that the proof of concept, i.e. the potential of reduced noise impact and fuel consumption over the same mission through trajectory optimization, is achieved. Developed methodology can be utilized to generate optimal flight routes and procedures specific to rotorcraft configuration, which are currently rather generic for all types of rotorcrafts, especially for booming e-VTOL platforms that will mostly operate over urban areas or for re-planning of legacy flight routes.
Citation Formats
A. Yücekayalı, “Noise minimal & green trajectory and flight profile optimization for helicopters,” Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering., Middle East Technical University, 2020.