Tonal Noise Reduction for a Maneuverable Marine Hydrokinetic Cycloturbine Vehicle Using Turbine Clocking

Abstract A Marine Hydrokinetic (MHK) cycloturbine vehicle can exploit tidal currents to generate sustainable power and also has the ability to station keep and maneuver. The vehicle consists of four counterrotating cycloturbines, which radiate sound underwater. Acoustic control is important to curtail the vehicle’s vibrations and acoustic signature, potentially preventing harmful effects on aquatic life, as well as to reduce the vehicle’s fatigue for longer deployment. A method of reducing the radiated acoustics of the vehicle is determined for tones at foil passing frequency and multiples, by means of clocking the blades between turbines. Experimental work includes testing of a subscale demonstrator in ARL’s Reverberant Tank facility. Fixing the subscale demonstrator to a reaction frame in the tank provides the ability to measure the generated loads using load cells. These measurements verify the effects of turbine clocking on the radiated acoustics.

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Acoustic Control of a Maneuverable Marine Hydrokinetic Cycloturbine

Volume 11: Acoustics, Vibration, and Phononics ◽

10.1115/imece2019-11381 ◽

2019 ◽

Author(s):

Margalit Z. Goldschmidt ◽

Michael L. Jonson ◽

Joseph F. Horn

Keyword(s):

Tonal Noise ◽

Compact Source ◽

Acoustic Control ◽

Acoustic Signature ◽

Short Period ◽

Entire Vehicle ◽

Marine Hydrokinetic ◽

Rate Frequency ◽

Cell Data ◽

Current Systems

Abstract Marine Hydrokinetic (MHK) cycloturbines exploit tidal currents to generate sustainable electric power. Because of the harsh marine environment, MHK cycloturbines require frequent maintenance and repair, which for current systems necessitates the use of a ship, making the process difficult and costly. A novel MHK cycloturbine system has been designed that uses pitching foils for maneuver, potentially circumventing the costs and difficulties associated with deployment and repairs. The vehicle fatigue is decreased and the vehicle’s acoustic signature underwater is reduced by design of a novel acoustic controller. This controller specifically reduces the tonal noise at blade rate frequency. Each turbine foil radiates noise equivalent to an acoustic dipole at multiples of blade rate frequency, and so the vehicle is modelled as an acoustic multipole. At blade rate frequency, the turbine size compared to its acoustic wavelength allows for the entire vehicle to be treated as a compact source. The effect of turbine clocking on directivity and sound power is shown. The effects of the designed controller to reduce tonal noise at blade rate frequency and multiples are verified experimentally through testing in ARL’s Reverberant Tank facility. Fixing a Subscale Demonstrator (SSD) to a reaction frame provides the ability to measure the integrated loads using load cells. The radiated sound pressure is computed for the load cell data obtained. Acoustic control is implemented using the turbine RPM: turbines are clocked by slowing one turbine relative to another for a short period of time.

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Extremum-seeking control applied to vortex shedding tonal noise reduction in a NACA0012 airfoil

10.26678/abcm.encit2020.cit20-0085 ◽

2020 ◽

Author(s):

Tarcísio Déda

Keyword(s):

Noise Reduction ◽

Vortex Shedding ◽

Extremum Seeking ◽

Tonal Noise ◽

Extremum Seeking Control ◽

Naca0012 Airfoil

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Experimental study of wavy trailing edge serrations on flat rotor blades

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-1970 ◽

2021 ◽

Vol 263 (5) ◽

pp. 1855-1866

Author(s):

Sai Manikanta Kaja ◽

K. Sriinivasan ◽

A. Jaswanth Kalyan Kumar

Keyword(s):

Experimental Study ◽

Noise Reduction ◽

Pitch Angle ◽

Acoustic Emissions ◽

Broadband Noise ◽

Rotor Blades ◽

Tonal Noise ◽

Trailing Edge ◽

Low Speeds ◽

Trailing Edge Serrations

A detailed experimental study is conducted to observe the effect of various parameters like wavelength, depth of serrations, and pitch angle on serrated blades' acoustic emissions at low speeds up to 2000 rpm. Experiments are conducted on flat blade rotors with sinusoidal serrations on the trailing edge of blades with different amplitudes and wavelengths. A total of 7 blades with different serration configurations, including a base configuration, are studied, five of them have serrations throughout the span of the blade, and one configuration has serration of varying amplitude on the farther half of the blade. It is observed that some blade configurations have resulted in tonal noise reduction noise as much as 8dB, whereas some of the serration configurations reduce very little to none, there is no significant effect of T.E serrations on the broadband noise emitted by the rotor. Directivity of noise generated from the rotor, the effect of serrations on the directivity of the noise is studied.

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Innovative passive multifrequency propeller device for noise and vibration reduction in turboprop fuselage

MATEC Web of Conferences ◽

10.1051/matecconf/201823300030 ◽

2018 ◽

Vol 233 ◽

pp. 00030 ◽

Cited By ~ 1

Author(s):

Angelo De Fenza ◽

Maurizio Arena ◽

Leonardo Lecce

Keyword(s):

Noise Reduction ◽

Tonal Noise ◽

Research Activity ◽

Noise Sources ◽

Noise And Vibration ◽

Aircraft Fuselage ◽

Research Sector ◽

Aeronautical Industry ◽

Flight Regimes ◽

Passive Noise

One of the main comfort issue affecting the passenger comfort into a turboprop aircraft fuselage is the propeller tonal noise and the related vibrations. It is well known that propeller rotation during flight generates the main noise sources, depending upon its rotational angular velocity, number of blades, power at shaft generating aircraft thrust and blades geometry. Thanks to the progress behind the control systems of the blades rotations, an innovative highly selective DVA has been conceived. The purpose of the research activity has been improving the performances of the standard passive tonal noise control system used for the BPF tuned noise and vibration attenuation in turboprop aircraft. Due to specific commercial need, the use of bi-tuned frequency can lead at a passive noise reduction at two RPM regimes. Generally, the turboprop aircrafts use only two RPM regimes: 100% at take-off, climb and approach, 86% during cruise, climb and descent. An innovative passive bi-tonal device capable to be tuned at two different frequencies in order to optimize the fuselage noise reduction at two different flight regimes (100% and 86%), has been designed and numerically verified. The functional effectiveness of the bi-frequential tuned device has been analysed by finite elements simulations on a linear beam, representative of the turboprop fuselage frame. The outcomes achieved within this activity encourage the advancement of this research sector, as a support to the needs of the turboprop aeronautical industry. According to the long experience gained by the research group, the proposed multifunctional concept can be a valid technology solution ready to be manufactured as well as validated in flight.

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Leveraging Surface Aeroacoustic-Structural Interaction for Airfoil Tonal Noise Reduction — A Parametric Study

25th AIAA/CEAS Aeroacoustics Conference ◽

10.2514/6.2019-2758 ◽

2019 ◽

Author(s):

Irsalan Arif ◽

Garret C. Y. Lam ◽

Randolph C. K. Leung ◽

Di Wu

Keyword(s):

Noise Reduction ◽

Parametric Study ◽

Tonal Noise ◽

Structural Interaction

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Passive airfoil tonal noise reduction by localized flow-induced vibration of an elastic panel

Aerospace Science and Technology ◽

10.1016/j.ast.2020.106319 ◽

2020 ◽

Vol 107 ◽

pp. 106319

Author(s):

Irsalan Arif ◽

Garret C.Y. Lam ◽

Di Wu ◽

Randolph C.K. Leung

Keyword(s):

Noise Reduction ◽

Tonal Noise ◽

Flow Induced Vibration

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Active Control of Structure-Borne Road Noise Using Vibration Actuators

Journal of Vibration and Acoustics ◽

10.1115/1.2893860 ◽

1998 ◽

Vol 120 (2) ◽

pp. 517-523 ◽

Cited By ~ 19

Author(s):

W. Dehandschutter ◽

P. Sas

Keyword(s):

Noise Reduction ◽

Laboratory Experiments ◽

Frequency Range ◽

Road Noise ◽

Control Approach ◽

Noise Radiation ◽

Acoustic Control ◽

Numerical Tools ◽

Control Set ◽

Set Up

Structure-borne road noise is generated by road induced excitation forces. The control approach presented here relies on the use of vibration actuators to modify the vibration behavior of the car body such that its noise radiation efficiency is decreased (Active Structural Acoustic Control—ASAC). The controller is optimized using laboratory experiments and numerical tools to simulate the performance a complete vehicle control set-up. Road tests yield a 6.9 dB noise reduction in the frequency range 75–105 Hz at the error microphone and 6.1 dB noise reduction at the passenger’s ear.

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