Numerical Investigation of an Optimized Rotor Head Fairing for the RACER Compound Helicopter in Cruise Flight

Abstract

The present work is part of the Clean Sky 2 project Full-Fairing Rotor Head Aerodynamic Design Optimization (FURADO), which deals with the aerodynamic design optimization of a full-fairing rotor head for the Rapid And Cost-Effective Rotorcraft (RACER) compound helicopter. The rotor head is a major drag source and previous investigations have revealed that the application of rotor head fairings can be an effective drag reduction measure. As part of the full-fairing concept, a new blade-sleeve fairing was aerodynamically optimized for cruise flight. Within this publication, the newly developed blade-sleeve fairing is put to test on an isolated, five-bladed rotor head and compared to an already existing reference blade-sleeve fairing, which was developed at Airbus Helicopters. Numerical flow simulations are performed with ANSYS Fluent 2019 R2 considering a rotating rotor head with cyclic pitch movement. The aerodynamic forces of the isolated rotor head are analyzed to determine the performance benefit of the newly developed blade-sleeve fairing. A drag reduction of 4.7% and a lift increase of 20% are obtained in comparison to the Airbus Helicopters reference configuration. Furthermore, selected surface and flow field quantities are presented to give an overview on the occurring flow phenomena.

Helicopter Main Rotor Blade Parametric Design for a Preliminary Aerodynamic Analysis Supported by CFD or Panel Method

“…As a new approach to rotorcraft design, we combined the parametric programming CAD model generator with the CFD and panel method, with the goal of providing new possibilities for improving the construction optimization procedure. The effects and possibilities of CFD main rotor studies that were implemented in the main rotor development procedure were well presented in [21][22][23]. In addition, a CFD analysis, as a base for a strength analysis because of load prediction, was clearly shown in [24].…”

Improved neural network adaptive control for compound helicopter with uncertain cross-coupling in multimodal maneuver

“…During the past decade, compound helicopters have grown dramatically in both military and civilian fields. However, due to unique characteristics of high speed rotor dynamic, these benefits must be balanced against many disadvantages including time-varying dynamics, mechanical difficulty, unknown aerodynamic interference of additional components, control difficulty and so on [1,2].…”

“…Although these methods have been proofed stability, the simple gradient descent adaptive law used in these literatures cannot guarantee the robustness of convergence in more complex systems. The improved PSNN adaptive control strategy for the compound helicopter should consider the following problems: (1) Stability should be ensured strictly in adaptive algorithm since multiplication neurons seriously damage robustness of PSNN; (2) The adaptive PSNN should be augmented with a robust controller architecture to keep robustness to inevitable parameters perturbation in converge process; (3) Practical control input to redundant control surfaces of compound helicopters should be allocated carefully to obtain a efficient tracking performance.…”