Investigation on a High-Frequency Controller for Rotor BVI Noise Alleviation

Anobile, Alessandro

doi:10.20855/ijav.2016.21.3416

Cited by 4 publications

(7 citation statements)

References 19 publications

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“…Active rotor control has been studied for several years, but most studies were for blade-vortex interaction (BVI) noise. It can be achieved through higher harmonic control [8][9][10], individual blade control [11][12][13], active flaps [14][15][16][17], and active twist [18][19][20]. The numerical and test results demonstrate that the active rotors are effective for BVI noise and vibration reduction as well as performance enhancement.…”

Section: Introductionmentioning

confidence: 99%

Helicopter Rotor Thickness Noise Control Using Unsteady Force Excitation

Shi

et al. 2019

Applied Sciences

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The low-frequency in-plane thickness noise generating from the displacement of air by rotating blades has an important influence on helicopter detection. An on-blade control technique to reduce thickness noise is developed in this paper based on the principle of sound field cancellation. Following the theoretical study on the mechanism of thickness noise reduction using in-plane unsteady force, a 2-m diameter rotor with an active trailing-edge winglet are designed and tested in a fully anechoic chamber. The winglet installed on the outboard blade is used to generate the unsteady force and anti-noise to counteract the thickness noise. The results demonstrate that effective reduction of thickness noise up to 3 dB is achieved in the front of the rotor when the winglet is under the one-harmonic control with 3 ° of deflection angle. Moreover, the experiments of frequency, amplitude, and phase scanning are carried out to study the parametric effects of winglet motions on noise reduction. The ability of noise reduction is proportional to the deflection amplitude of the winglet in each frequency. The control phase determines where noise can be reduced. There is an optimal phase angle at each frequency to minimize the noise at the observations, and it varies with different frequencies. The relationship among observation position, control phase, and frequency is derived, and the approximate expression of the optimal phase is presented.

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Section: Introductionmentioning

confidence: 99%

Helicopter Rotor Thickness Noise Control Using Unsteady Force Excitation

Shi

et al. 2019

Applied Sciences

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“…The latter, like higher harmonic control (HHC), individual blade control (IBC), or active trailingedge flap control, use relatively low-frequency actuation inputs to produce blade response by increasing the miss distance i.e., the relative distance between vortex and blade, thus alleviating BVI effects. However, the success of these techniques, shown to be capable of considerable BVI noise reduction, [1][2][3][4] often corresponds to increased rotor vibrations.…”

Section: Introductionmentioning

confidence: 99%

“…Based on an optimal linear-quadratic multi-cyclic local controller capable of generating anti-BVI loads through multi-harmonic pitch motion of a suitable blade portion, that procedure offered the opportunity of reducing BVI noise without the drawback of structural vibrations. 4,5 Numerical investigations have shown promising results, although suggesting further developments concerning its feasibility and the efficiency of the process for control law determination. These two issues are examined in the present work, with the introduction of realistic control actuation devices on the blade, and with the application of an efficient semi-analytical method for the controller identification.…”

Section: Introductionmentioning

confidence: 99%

Blade-Vortex Interaction Noise Controller Based on Miniature Trailing Edge Effectors

Modini¹,

Graziani²,

Bernardini³

et al. 2018

The International Journal of Acoustics and Vibration

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The present work focuses on the alleviation of Blade Vortex Interaction (BVI) noise annoyance through a control methodology generating high-frequency aerodynamic BVI counter-actions. The low-power requirements make the Micro-Trailing Edge Effectors (MiTEs) particularly suited for this kind of application. The controller layout is set by observing the BVI scenario while the actuation law is efficiently synthesized through a process based on an analytical unsteady sectional aerodynamic formulation. The validation of the proposed control methodology is carried out through numerical investigations of a realistic helicopter main rotor in flight descent, obtained using computational tools for potential-flow aerodynamic and aeroacoustic analyses based on boundary element method solutions. In order to capture the aerodynamic influence of MiTEs through potential-flow simulations, the MiTEs are replaced by trailing edge plain flaps which provide equivalent aerodynamic responses. Results concerning the proposed controller capability to alleviate high-frequency blade loads and subsequent emitted noise from BVI events are presented and discussed.

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“…The actuation harmonics were those of BVI loads, with amplitudes given by a closed-loop control law determined through an optimal linear-quadratic multi-cyclic controller, efficiently synthesized by exploiting two-dimensional (2D) equivalent parallel BVI problems. A similar approach based upon an individual blade high-frequency controller, exploiting active twist actuation to reduce BVI rotor noise, has been also proposed and investigated in Anobile et al 15,16 . Numerical solutions presented in Modini et al [12][13][14] and Anobile et al 15,16 have shown promising results, suggesting the need of further developments and investigations aimed at assessing the feasibility of such kind of control approach.…”

Section: Introductionmentioning

confidence: 99%

“…A similar approach based upon an individual blade high-frequency controller, exploiting active twist actuation to reduce BVI rotor noise, has been also proposed and investigated in Anobile et al. 15,16 . Numerical solutions presented in Modini et al.…”

Section: Introductionmentioning

confidence: 99%

Pressure feedback-based blade–vortex interaction noise controller for helicopter rotors

Modini

Graziani

Bernardini

et al. 2018

International Journal of Aeroacoustics

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With the aim of alleviating the noise annoyance emitted by blade-vortex interactions occurring on helicopter main rotors, the present work presents a methodology suitable for the identification of a multi-cyclic harmonic controller based on the actuation of rotor blades equipped with Miniature Trailing Edge Effectors. The objective of the control methodology is the direct suppression of the aerodynamic noise sources by generation of localized high-harmonic bladevortex interaction counter-actions. The setup of control devices is selected on the basis of the blade-vortex interaction scenario, taking into account a trade-off between effectiveness and power requirement. The control law is efficiently identified by means of an optimal controller synthesized through suitable two-dimensional multi-vortex, parallel blade-vortex interaction problems. The proposed methodology is validated by the application to realistic helicopter main rotors during low-speed descent flights, numerically simulated through high-fidelity aerodynamic and aeroacoustic solvers based, respectively, upon a three-dimensional free-wake boundary element method to solve the potential flow around rotors in blade-vortex interaction conditions and the Farassat 1A formulation. Results concerning the capability of the proposed controller to alleviate the blade-vortex interaction noise emitted by a realistic helicopter main rotor are presented and discussed.

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Investigation on a High-Frequency Controller for Rotor BVI Noise Alleviation

Cited by 4 publications

References 19 publications

Helicopter Rotor Thickness Noise Control Using Unsteady Force Excitation

Helicopter Rotor Thickness Noise Control Using Unsteady Force Excitation

Blade-Vortex Interaction Noise Controller Based on Miniature Trailing Edge Effectors

Pressure feedback-based blade–vortex interaction noise controller for helicopter rotors

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