scholarly journals Rotor system having alternating length rotor blades for reducing blade-vortex interaction (BVI) noise

1998 ◽  
Vol 103 (5) ◽  
pp. 2259
Author(s):  
Robert C. Moffitt ◽  
Joseph A. Visintainer
Keyword(s):  
Rotor System ◽  
Rotor Blades ◽  
Vortex Interaction ◽  
Blade Vortex Interaction

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

2018 ◽  
Vol 17 (3) ◽  
pp. 295-318 ◽  
Author(s):  
Sara Modini ◽  
Giorgio Graziani ◽  
Giovanni Bernardini ◽  
Massimo Gennaretti
Keyword(s):  
High Harmonic ◽  
Three Dimensional ◽  
Rotor Blades ◽  
Aerodynamic Noise ◽  
Vortex Interaction ◽  
Noise Sources ◽  
Power Requirement ◽  
Blade Vortex Interaction ◽  
Pressure Feedback ◽  
Helicopter Main Rotor

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 blade–vortex interaction counter-actions. The set-up 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.

Computational aeroelastic analysis of slowed rotors at high advance ratios

2014 ◽  
Vol 118 (1201) ◽  
pp. 297-313 ◽  
Author(s):  
J. de Montaudouin ◽  
N. Reveles ◽  
M. J. Smith
Keyword(s):  
High Speed ◽  
Rotor Blades ◽  
Vortex Interaction ◽  
Blade Loading ◽  
Blade Vortex Interaction ◽  
Aeroelastic Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Advance Ratio ◽  
Cfd Method ◽  
Model Rotor

Abstract The aerodynamic and aeroelastic behaviour of a rotor become more complex as advance ratios increase to achieve high-speed forward fight. As the rotor blades encounter large regions of cross and reverse flows during each revolution, strong variations in the local Mach regime are encountered, inducing complex elastic blade deformations. In addition, the wake system may remain in the vicinity of the rotor, adding complexity to the blade loading. The aeroelastic behaviour of a model rotor with advance ratios ranging from 0·5 to 2·0 has been evaluated with aerodynamics provided via a computational fluid dynamics (CFD) method. Significant radial blade-vortex interaction can occur at a high advance ratio; the advance ratio at which this occurs is dependent on the rotor configuration. This condition is accompanied by high vibratory loads, peak negative torsion, and peak torsion and in-plane loads. The high vibratory loading increases the sensitivity of the trim model, so that at some high advance ratios the vibratory loads must be filtered to achieve a trimmed state.

Fundamental investigation using active plasma control to reduce blade–vortex interaction noise

2021 ◽  
pp. 1475472X2110526
Author(s):  
Trushant K Patel ◽  
Alexander J Lilley ◽  
Weiqi Shen ◽  
Christian Porrello ◽  
Alexander Schindler-Tyka ◽  
...  
Keyword(s):  
Rotor Blades ◽  
Tip Vortex ◽  
Plasma Actuators ◽  
Supporting Evidence ◽  
Vortex Interaction ◽  
Dominant Component ◽  
Fundamental Investigation ◽  
Blade Vortex Interaction ◽  
Aerial Vehicle ◽  
Blade Tip

Blade vortex interaction noise is a problematic and dominant component of rotor noise. Plasma actuators strategically placed at the tip of the rotor blades can reduce the strength of the tip vortices. This reduction has the potential to significantly reduce blade vortex interaction noise. A combined experimental, numerical, and theoretical program shows supporting evidence that low power plasma actuators can effectively lower coherence of the blade tip vortex and reduce blade vortex interaction noise over-pressure by up to 80%. For a nominal small five-bladed unmanned aerial vehicle, we predict an approximate 8.88 maximum ΔdB reduction for a 150 m/s tip speed. Experimental, computational, and acoustic modeling support these predictions. This study represents a fundamental investigation in the fixed-frame, which provides evidence for higher level research and testing in a rotating framework.

Novel method for calculating two-dimensional blade vortex interaction

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 909-912
Author(s):  
Ronald J. Epstein ◽  
John A. Rule ◽  
Donald B. Bliss
Keyword(s):  
Two Dimensional ◽  
Vortex Interaction ◽  
Blade Vortex Interaction ◽  
Novel Method

Blade-vortex interaction experiments - Velocity and vorticity fields

1990 ◽  
Author(s):  
MICHAEL WILDER ◽  
MATTHEW PESCE ◽  
DEMETRI TELIONIS ◽  
DAVIDR. POLING
Keyword(s):  
Vortex Interaction ◽  
Blade Vortex Interaction

A modified near wake dynamic model for rotor analysis

1999 ◽  
Vol 103 (1021) ◽  
pp. 143-146 ◽  
Author(s):  
T. Wang ◽  
F. N. Coton
Keyword(s):  
High Resolution ◽  
Dynamic Model ◽  
Numerical Evaluation ◽  
Helicopter Rotor ◽  
Vortex Interaction ◽  
Near Wake ◽  
Blade Vortex Interaction ◽  
Wake Model ◽  
Induced Velocity

Abstract The Beddoes near wake model, developed for high resolution blade vortex interaction computations, enables efficient numerical evaluation of the downwash due to trailed vorticity in the near wake of a helicopter rotor. The model is, however, limited by the assumption that the near wake lies in the plane of the rotor and, in some cases, by its inability to accurately evaluate the induced velocity contribution from vorticity trailed from inboard blade sections. In this paper, modifications to the method are proposed which address these issues and allow it to be used with confidence over a wider range of rotor flows.

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