Exploring Airfoil Tonal Noise Reduction with Elastic Panel Using Perturbation Evolution Method

AIAA Journal ◽  
2020 ◽  
Vol 58 (11) ◽  
pp. 4958-4968 ◽  
Author(s):  
I. Arif ◽  
Di Wu ◽  
Garret C. Y. Lam ◽  
Randolph C. K. Leung
Keyword(s):  
Noise Reduction ◽  
Tonal Noise

Experimental study of wavy trailing edge serrations on flat rotor blades

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.

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

2018 ◽  
Vol 233 ◽  
pp. 00030 ◽  
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.

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

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Margalit Z. Goldschmidt ◽  
Michael L. Jonson ◽  
Joseph Horn
Keyword(s):  
Noise Reduction ◽  
Experimental Work ◽  
Tonal Noise ◽  
Aquatic Life ◽  
Acoustic Control ◽  
Acoustic Signature ◽  
Load Cells ◽  
Marine Hydrokinetic ◽  
Sustainable Power ◽  
Harmful Effects

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.

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

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

A compact active control system for tonal noise reduction in axial fans

Noise Notes ◽  
2007 ◽  
Vol 6 (3) ◽  
pp. 37-46
Author(s):  
Anthony Gerard ◽  
Alain Berry ◽  
Patrice Masson
Keyword(s):  
Control System ◽  
Noise Reduction ◽  
Active Control ◽  
Tonal Noise ◽  
Axial Fans ◽  
Active Control System

Numerical Study of Airfoil Tonal Noise Reduction using Segmented Elastic Panel Configuration

2021 ◽  
Vol 263 (4) ◽  
pp. 2916-2929
Author(s):  
Arif Muhammad Irsalan ◽  
Garret C. Y. Lam ◽  
Randolph C. K. Leung
Keyword(s):  
Reynolds Number ◽  
Noise Reduction ◽  
Numerical Study ◽  
Separation Bubble ◽  
Low Reynolds Number ◽  
Flow Characteristics ◽  
Tonal Noise ◽  
Airfoil Surface ◽  
Passive Method ◽  
Low Reynolds

In this paper, a novel passive method for airfoil tonal noise reduction is proposed using a configuration of two segmented elastic panels mounted on the airfoil. Numerical investigation using perturbation evolution method is carried out at a low Reynolds number based on airfoil chord of 5x10 and an angle of attack of 5. The passive method of employing a single panel has shown promising tonal noise reduction capabilities where the resonating panel located just ahead of the sharp growth of boundary layer instability within the airfoil separation bubble provided the strongest reduction of instabilities and noise reduction up to 3 dB has been achieved. The idea is extended in the present study by employing a two-panel configuration based on the localized flow characteristics over the airfoil surface. Five different panel configurations are designed and their effectiveness in terms of tonal noise reduction is evaluated and compared with baseline configuration. The azimuth and spectral analyses indicate the different extent of noise reduction for each configuration and even noise amplification in one of them. A significant noise reduction up to 8 dB is observed for the optimum configuration indicating the effectiveness of this novel method for devices operating at low Reynolds number.

A Compact Active Control System for Tonal Noise Reduction in Axial Fans

2007 ◽  
Vol 38 (4) ◽  
pp. 12-18
Author(s):  
Anthony Gérard ◽  
Alain Berry ◽  
Patrice Masson
Keyword(s):  
Control System ◽  
Noise Reduction ◽  
Active Control ◽  
Tonal Noise ◽  
Axial Fans ◽  
Active Control System
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