Impact of optimized variable rotor speed and active blade twist control on helicopter blade–vortex interaction noise and environmental impact

The concept of Variable Rotor Speed (VRS) has been recognized as an efficient means to improve rotorcraft operational performance and environmental impact, with electrification being a potential technology to further contribute to that. This paper explores the impact of optimal implementation and scheduling of VRS and power management strategy for conventional and hybrid-electric rotorcraft on energy, fuel, and emissions footprint. A multidisciplinary simulation framework for rotorcraft performance combined with models for engine performance and gaseous emissions estimation is deployed. A holistic optimization approach is developed for the derivation of globally optimal schedules for combined rotor speed and power split targeting minimum energy consumption. Application of the derived optimal schedules at mission level resulted to a 6% improvement in range capability for the VRS tilt-rotor relative to its conventional counterpart. For the hybrid-electric tilt-rotor, combined optimization of VRS and power management leads to an increase in range to 18.4% at 40% and 25% reduced payload for current (250 Wh/kg) and future (450 Wh/kg) battery technology, respectively. For representative Urban Air Mobility (UAM) scenarios, it is demonstrated that the VRS concept resulted in up to 10% and 14% reductions in fuel burn and NOX relative to the nominal rotor speed case, respectively. The utilization of the combined optimum VRS and power split schedules can boost performance with reductions of the order of 20%and 25% in mission fuel/CO2 and NOX at a reduced payload relative to the conventional tilt-rotor.

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“…This strategy is an expansion of the approach introduced by Goulos et al [16] and later adopted in Refs. [17,18,40].…”

Section: Design Space Exploration and Optimizationmentioning

confidence: 99%

On the Effects of Optimal Implementation of Variable Rotor Speed and Power Management on Hybrid-Electric Rotorcraft

Saias

Goulos

Pachidis

et al. 2023

Journal of Engineering for Gas Turbines and Power

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“…Snider et al (2013) developed a method for rotorcraft broadband noise prediction related to civil noise certification. Vouros et al (2021) discussed the impact of morphing rotor optimization on ground noise levels of rotorcraft following the EASA descent certification trajectory (ICAO, 2008). A numerical procedure for the prediction of certification noise generated by aircraft landing gear was presented by Casalino et al (2012).…”

Section: Certificationmentioning

confidence: 99%

“…In this context, the impact of conceptual design changes on aircraft certification capability shall be brought up earlier in the development process Snider et al (2013). developed a method for rotorcraft broadband noise prediction related to civil noise certification Vouros et al (2021). discussed the impact of morphing rotor optimization on ground noise levels of rotorcraft following the EASA descent certification trajectory(ICAO, 2008).…”

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confidence: 99%

Noise of Future Aircraft Propulsion: Sources and Design Considerations

Protopapadakis¹,

Gkoutzamanis²,

Vouros³

et al. 2022

Proceedings of Global Power &Amp; Propulsion Society

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This paper attempts to reduce the gap, when it comes to future aircraft concepts noise and aeroacoustics, and at the same time introduce basic noise aspects for people unfamiliar to it. This is performed by taking into account the following four stages: Identification of conventional aircraft noise sources, overview of the aeroacoustics of future aircraft configurations, derivation of conceptual design considerations for noise issues, and finally, insight on the impact of technology advancements on certification. More specifically, a holistic overview of the aeroacoustics of aircraft was performed. The noise sources were described and made available for those unacquainted with the subject. Aeroacoustic behavior of ContraRotating Open Rotors, Boundary Layer Ingestion and Distributed Propulsion concepts was studied trough the most recent and relevant literature. The phenomena causing noise were highlighted, and the differences between conventional and future designs detected. It was found that generally noise sources are similar, but the intensity of some can be significantly altered. Early design phase guidelines were extracted for each of the concepts. The design considerations are grouped into a matrix showing the relative effect of each on noise emissions. With these guidelines, it is possible to perform design choices in the conceptual level of fidelity for future aircraft concepts. Furthermore, certification aspects and observations considering its future development are presented. Noise emissions are expected to change, and thus certification must be adapted to it. Furthermore, in this quick advancing technology field, virtual certification is advised to be used.

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“…As for the rotor system with multiple rotors rotating at the same rotation speed, each of the rotors can be regarded as an individual sound source, and the noise can be modified by only adjusting the initial angles of the rotors. Moreover, the shapes of the blades are not changed, and the noise cancellation can be realized without changing the of dynamic characteristics [16][17][18][19][20][21][22][23][24]. Guan et al have carried out a noise attenuation experiment with a quadrotor using the phase synchronization method [25].…”

Section: Introductionmentioning

confidence: 99%

A Dynamic RCS and Noise Prediction and Reduction Method of Coaxial Tilt-Rotor Aircraft Based on Phase Modulation

Wang

Huang

et al. 2022

Sensors

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For tilt-rotor aircraft with coaxial rotors (coaxial rotor aircraft), reduction of radar cross section as well as acoustic noise can be essential for stealth design, and the rotation of the coaxial rotors can have an influence on noise and dynamic radar cross section (RCS) characteristics. In this paper, an approach to the prediction of both the sound pressure level (SPL) of noise and the dynamic RCS of coaxial-tilt aircraft is carried out, based on the theories of the FW-H equation, the physics optics method (PO) and the physical theory of diffraction (PTD) method. In order to deal with the rotating parts (mainly including coaxial rotors), a generated rotation matrix (GRM) is raised, aiming at giving a universal formula for the time-domain grid coordinate transformation of all kinds of rotation parts with arbitrary rotation centers and rotation axis directions. Moreover, a compass-scissors model (CSM) reflecting the phase characteristics of coaxial rotors is established, and a method of noise reduction and RCS reduction based on the phase modulation method is put forward in this paper. The simulation results show that with proper CSM parameter combinations, the reduction of noise SPL can reach approximately 3~15 dB and the reduction of dynamic RCS can reach 1.6 dBsm at most. The dynamic RCS and noise prediction and reduction method can be meaningful for the radar-acoustic stealth design of coaxial tilt-rotor aircrafts.

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Impact of optimized variable rotor speed and active blade twist control on helicopter blade–vortex interaction noise and environmental impact

Cited by 6 publications

References 42 publications

On the Effects of Optimal Implementation of Variable Rotor Speed and Power Management on Hybrid-Electric Rotorcraft

On the Effects of Optimal Implementation of Variable Rotor Speed and Power Management on Hybrid-Electric Rotorcraft

Noise of Future Aircraft Propulsion: Sources and Design Considerations

A Dynamic RCS and Noise Prediction and Reduction Method of Coaxial Tilt-Rotor Aircraft Based on Phase Modulation

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