Recent Rotor Wake Simulation And Modeling Studies At United Technologies Corporation

Author : Andrew Jue
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (142 download)

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Download or read book Simulation of Advanced Rotorcraft Concepts Using Free Wake Aerodynamic Models written by Andrew Jue and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the flight dynamics of two different electric vertical takeoff and landing aircraft was performed using the Distributed Electric Propulsion Simulation (DEPSim). DEPSim incorporates a free-wake model that allows for prediction of aerodynamic interactions, so the use of DEPSim allows for investigation of the effects that aerodynamic interactions can have on flight dynamics. One of the two aircraft studied was a generic lift+cruise multicopter proposed for urban air mobility (UAM) use. The aircraft has four lift rotors in a quad configuration along with a wing, tail, and pusher propeller. The other aircraft studied was the Dragonfly octocopter planned for exploration of Saturn's moon Titan. It is a multicopter with four coaxial rotor pairs arranged in a quad configuration. For both aircraft, a variety of dynamic maneuvers were investigated. Specifically, for the lift+cruise aircraft, departure maneuvers and approach maneuvers were investigated. For these maneuvers, the flight dynamics were analyzed in addition to the power and energy consumption. The departure simulations, which compared different ways to transition to wing-borne flight, showed that the departure maneuver that reached wing-borne flight the quickest used the least energy, 58% of the energy of the maneuver that reached wing-borne flight the slowest. Additionally, significant rotor-wing interference was observed for this aircraft in both departure and approach maneuvers. This interference arises from changes in the effective angle of attack on the wing due to the induced velocity from the rotor wake. These angle of attack changes are correlated with the thrust differential of the front rotors and result in the generation of a rolling moment by the wings due to lift asymmetry. It was found that thrust differentials between the front two rotors resulted in a significant rolling moment that was close to 4 times the pusher propeller torque. A change in control allocation alleviated the problem and reduced the rolling moment. For the approach maneuvers, it was found that the effect of both the rolling moment from interference and the change in control allocation depended on the aircraft pitch during the maneuver. For Dragonfly, the transition to powered flight maneuver was investigated. Additionally, the dynamics of the aircraft were studied through the calculation of stability derivatives and linear models at hover, 1 m/s, 5 m/s, and 10.5 m/s. The transition to powered flight, along with select stability and control derivatives, were compared to reference data for verification. For the transition to powered flight, two separate versions were performed: one had the rotors running throughout the entire simulation while another included the rotor start-up component of the maneuver. Both maneuvers were able to track the reference data fairly well with predicted rear rotor speed and rotor thrust slightly higher than the reference data. Two versions of the stability and control derivatives were also generated. One version included wing struts in the model while the other did not, and a small impact on the results generated was seen due to the aerodynamic interference with the wing struts. Overall, the stability and control derivatives matched well with the reference data even with the different aerodynamic interactions. This shows decent verification of the reference data with the DEPSim aerodynamic model and the interactions the model captures.