Citation:
Scullion C, Vouros S, Goulos I, et al., (2020) Optimal control of a compound rotorcraft for engine performance enhancement. In: ASME Turbo Expo 2020, 21-25 September 2020, London, Virtual Event. Paper number GT2020-16280
Abstract:
Demands for rotorcraft with increased flight speed, improved
operational performance and reduced environmental impact
have led to a drive in research and development of alternative
concepts. Compound rotorcraft overcome the flight speed
limitations of conventional helicopters with additional lifting
and propulsive components. Further to operational benefits,
these augmentations provide additional flight control
parameters, resulting in control redundancy. This work aims to
investigate the impact of optimal control strategies for a generic
coaxial compound rotorcraft, equipped with turboshaft engines,
targeting the minimization of mission fuel burn and gaseous
emissions. The direct redundant controls considered are: (a)
main rotor speed, (b) propeller speed, and (c), fuselage pitch
attitude. A simulation tool for coaxial compound rotorcraft
analysis has been developed and coupled to a zero-dimensional
engine performance model and a stirred-reactor combustor
model. Firstly, experimental and flight test data were used to
provide extensive validation of the developed models. A
parametric analysis was then carried out to gain insight into the
effect of the redundant controls. This was followed by the
derivation of a generalized set of optimal redundant control
allocations using a surrogate-assisted genetic algorithm.
Application of the optimal redundant control allocations during
realistic operational scenarios has demonstrated reductions in
fuel burn and NOX of up to 6.93% and 8.74% respectively. The
developed method constitutes a rigorous approach to guide the
design of control systems for future advanced rotorcraft