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.

Study on the aerodynamic noise of internal flow of regenerative flow compressors for a fuel-cell car

2013 ◽  
Vol 228 (7) ◽  
pp. 1155-1174 ◽  
Author(s):  
Qiang Kang ◽  
Shuguang Zuo ◽  
Kaijun Wei
Keyword(s):  
Finite Element ◽  
Fuel Cell ◽  
Dynamic Model ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Internal Flow ◽  
Aerodynamic Noise ◽  
Noise Sources ◽  
Element Analysis ◽  
Regenerative Flow

The regenerative flow compressor used in fuel-cell cars generates high aerodynamic noise, which is the main source of noise. Compared with the research on centrifugal or axial turbomachinery, research on the noise of regenerative flow compressors is far from adequate. This paper presents the on-going work on it at Tongji University based on both experimental and computational works. In this study, a three-dimensional unsteady computational fluid dynamic model of the compressor was constructed with the large eddy approach. The pressure fluctuation, vortex noise source and Ffowcs William-Hawkings (FW-H) method were used to analyze the characteristics of the aerodynamic noise sources. Additionally, the far-field aerodynamic noise generated by the internal flow of the compressor was predicted using the aeroacoustic finite element method. The simulation results were validated with the experimental data. It was found that combining the fluid dynamic model and aeroacoustic finite element analysis promising results for aerodynamic noise prediction of compressors could be produced. The effects of the impeller parameters on the aerodynamic noise of the compressor were also studied.

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.

On the three-dimensional nature of the orthogonal blade–vortex interaction

2006 ◽  
Vol 41 (5) ◽  
pp. 749-761 ◽  
Author(s):  
R. B. Green ◽  
F. N. Coton ◽  
J. M. Early
Keyword(s):  
Three Dimensional ◽  
Vortex Interaction ◽  
Blade Vortex Interaction

scholarly journals Impact of Tip-Vortex Modeling Uncertainty on Helicopter Rotor Blade–Vortex Interaction Noise Prediction

2021 ◽  
Vol 66 (1) ◽  
pp. 1-13
Author(s):  
Stavros Vouros ◽  
Ioannis Goulos ◽  
Calum Scullion ◽  
Devaiah Nalianda ◽  
Vassilios Pachidis
Keyword(s):  
Vortex Core ◽  
Numerical Procedure ◽  
Tip Vortex ◽  
Analytical Models ◽  
Aerodynamic Noise ◽  
Helicopter Rotor ◽  
Vortex Interaction ◽  
Blade Vortex Interaction ◽  
Free Wake ◽  
The Impact

Free-wake models are routinely used in aeroacoustic analysis of helicopter rotors; however, their semiempiricism is accompanied with uncertainty related to the modeling of physical wake parameters. In some cases, analysts have to resort to empirical adaption of these parameters based on previous experimental evidence. This paper investigates the impact of inherent uncertainty in wake aerodynamic modeling on the robustness of helicopter rotor aeroacoustic analysis. A free-wake aeroelastic rotor model is employed to predict high-resolution unsteady airloads, including blade–vortex interactions. A rotor aeroacoustics model, based on integral solutions of the Ffowcs Williams–Hawkings equation, is utilized to calculate aerodynamic noise in the time domain. The individual analytical models are incorporated into an uncertainty analysis numerical procedure, implemented through nonintrusive Polynomial Chaos expansion. The potential sources of uncertainty in wake tip-vortex core growth modeling are identified and their impact on noise predictions is systematically quantified. When experimental data to adjust the tip-vortex core model are not available the uncertainty in acoustic pressure and noise impact at observers dominated by blade–vortex interaction noise can reach up to 25% and 3.50 dB, respectively. A set of generalized uncertainty maps is derived, for use as modeling guidelines for aeroacoustic analysis in the absence of the robust evidence necessary for calibration of semiempirical vortex core models.

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

2018 ◽  
Vol 23 (No 3, September 2018) ◽  
pp. 378-384 ◽  
Author(s):  
Sara Modini ◽  
Giorgio Graziani ◽  
Giovanni Bernardini ◽  
Massimo Gennaretti
Keyword(s):  
Potential Flow ◽  
High Frequency ◽  
Vortex Interaction ◽  
Trailing Edge ◽  
Computational Tools ◽  
Flow Simulations ◽  
Blade Vortex Interaction ◽  
Helicopter Main Rotor ◽  
Control Methodology ◽  
Blade Loads

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.

A Numerical Investigation of the Influence of the Blade–Vortex Interaction on the Dynamic Stall Onset

2021 ◽  
Author(s):  
Camille Castells ◽  
François Richez ◽  
Michel Costes
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Dynamic Stall ◽  
Test Case ◽  
Vortex Interaction ◽  
Fluid Structure ◽  
Speed Test ◽  
Vortex Model ◽  
Flow Parameters ◽  
Blade Vortex Interaction

Recently, fluid–structure coupling simulations of helicopter rotors in high-thrust forward flight suggested that dynamic stall might be triggered by the blade–vortex interaction. However, no clear evidence of a correlation between dynamic stall and blade–vortex interaction has yet been given. We propose in this paper a simplified two-dimensional numerical model that can be used to indicate the role that the blade–vortex interaction plays in dynamic stall onset for different flight conditions. In this model, the rotor blade element is considered in pitching oscillation motion with a nonuniform translation, and a simplified vortex model can be introduced or not in the simulation to highlight the effect of blade–vortex interaction. All flow parameters of this simplified model are deduced from data provided by previous three-dimensional high-fidelity fluid–structure simulations. The method is used for validation and analysis of three flight conditions. The results show that, for the two cases with moderate advance ratio, the dynamic stall event is only triggered when a blade–vortex interaction occurs in the stall region. For the high-speed test case, the dynamic stall event seems to be only triggered by the very high angle of attack due to the motion of the blade.

Aeroelastic response of helicopter rotors using a 3D unsteady aerodynamic solver

2006 ◽  
Vol 110 (1114) ◽  
pp. 793-801 ◽  
Author(s):  
M. Gennaretti ◽  
G. Bernardini
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Spatial Integration ◽  
Aeroelastic Response ◽  
Blade Vortex Interaction ◽  
Aeroelastic Model ◽  
Aerodynamic Interaction ◽  
Helicopter Main Rotor ◽  
The Galerkin Method

The prediction of blade deflections and vibratory hub loads concerning helicopter main rotors in forward flight is the objective of this work. They are determined by using an aeroelastic model derived through the coupling between a nonlinear blade structural model and a boundary integral equation solver for three-dimensional, unsteady, potential aerodynamics. The Galerkin method is used for the spatial integration, whereas the periodic blade response is determined by a harmonic balance approach. This aeroelastic model yields a unified approach for aeroelastic response and blade pressure prediction that may be used for aeroacoustic purposes, with the possibility of including effects from both blade-vortex interaction and multiple-body aerodynamic interaction. Quasi-steady aerodynamic models with wake-inflow from the three-dimensional aerodynamic solver are also applied, in order to perform a comparative study. Numerical results show the capability of the aeroelastic tool to evaluate blade response and vibratory hub loads for a helicopter main rotor in level flight conditions, and examine the sensitivity of the predictions on the aerodynamics model used.

Computational Analysis of Noise Sources Inside the High Speed Flow Over a Bump

2007 ◽  
Author(s):  
Kentaro Okamoto ◽  
Taku Nonomura ◽  
Kozo Fujii
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Noise ◽  
Stream Line ◽  
Noise Sources ◽  
Bump Height ◽  
Speed Flow ◽  
Low Pass

The aerodynamic noise sources around the three dimensional bump are studied. In this search, pressure fluctuation on the wall which effects interior noise is searched using ILES. The ratio of the bump diameter (D) and height (H) is D/H = 4. In front of the bump, the boundary layer thickness is half of the bump height. Reynolds number based on the bump height was 65000 and the free stream Mach number is 0.1. In flow boundary layer profile is given by using rescaling method and the laminar boundary layer is changed into turbulent boundary layer. Sixth-order-accurate compact scheme is used to represent spatial derivatives and six-order low pass spatial filtering procedure is utilized for removing numerical oscillations. First, instantaneous flow field is discussed. Second, characteristics of time average flow field, such as Cp distribution and stream line topology, are discussed. Third, spanwise velocity fluctuation and sound pressure level on the wall are discussed.

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