Towards Numerical Simulation of Fan Broadband Noise Propagation and Radiation from Aero-Engines

2009 ◽  
Author(s):  
Gabriel Reboul ◽  
Cyril Polacsek ◽  
Guillaume Desquesnes
Keyword(s):  
Numerical Simulation ◽  
Broadband Noise ◽  
Noise Propagation ◽  
Aero Engines

Numerical simulation for fan broadband noise prediction

2011 ◽  
Vol 20 (1) ◽  
pp. 58-63 ◽  
Author(s):  
Takaaki Hase ◽  
Nobuhiko Yamasaki ◽  
Tsutomu Ooishi
Keyword(s):  
Numerical Simulation ◽  
Broadband Noise ◽  
Noise Prediction

scholarly journals Experimental Study of Advanced Helmholtz Resonator Liners with Increased Acoustic Performance by Utilising Material Damping Effects

2018 ◽  
Vol 8 (10) ◽  
pp. 1923
Author(s):  
Martin Dannemann ◽  
Michael Kucher ◽  
Eckart Kunze ◽  
Niels Modler ◽  
Karsten Knobloch ◽  
...  
Keyword(s):  
Polymer Films ◽  
Helmholtz Resonator ◽  
Broadband Noise ◽  
Acoustic Energy ◽  
Acoustic Damping ◽  
Acoustic Performance ◽  
Acoustic Liners ◽  
Flexible Polymer ◽  
Noise Absorption ◽  
Aero Engines

In aero engines, noise absorption is realised by acoustic liners, e.g., Helmholtz resonator (HR) liners, which often absorb sound only in a narrow frequency range. Due to developments of new engine generations, an improvement of overall acoustic damping performance and in particular more broadband noise absorption is required. In this paper, a new approach to increase the bandwidth of noise absorption for HR liners is presented. By replacing rigid cell walls in the liner’s honeycomb core structure by flexible polymer films, additional acoustic energy is dissipated. A manufacturing technology for square honeycomb cores with partially flexible walls is described. Samples with different flexible wall materials were fabricated and tested. The acoustic measurements show more broadband sound absorption compared to a reference liner with rigid walls due to acoustic-structural interaction. Manufacturing-related parameters are found to have a strong influence on the resulting vibration behaviour of the polymer films, and therefore on the acoustic performance. For future use, detailed investigations to ensure the liner segments compliance with technical, environmental, and life-cycle requirements are needed. However, the results of this study show the potential of this novel liner concept for noise reduction in future aero-engines.

scholarly journals J091043 Numerical simulation of broadband noise generated from a square cylinder

2011 ◽  
Vol 2011 (0) ◽  
pp. _J091043-1-_J091043-3
Author(s):  
Naoki MASUDA ◽  
Chisachi KATO ◽  
Yasumasa SUZUKI
Keyword(s):  
Numerical Simulation ◽  
Broadband Noise ◽  
Square Cylinder

Pore-Level Numerical Simulation of Open-Cell Metal Foams With Application to Aero Engine Separators

2014 ◽  
Author(s):  
Thiago Piazera de Carvalho ◽  
Hervé P. Morvan ◽  
David Hargreaves
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Porous Medium ◽  
Pressure Drop ◽  
Metal Foam ◽  
Metal Foams ◽  
Open Cell ◽  
X Ray ◽  
Pore Level ◽  
Aero Engines

In aero engines, the oil and air interaction within bearing chambers creates a complex two-phase flow. Since most aero engines use a close-loop oil system and releasing oil out is not acceptable, oil-air separation is essential. The oil originates from the engine transmission, the majority of which is scavenged out from the oil pump. The remainder exits via the air vents, where it goes to an air oil separator called a breather. In metal-foam-style breathers separation occurs by two physical processes. Firstly the largest droplets are centrifuged against the separator walls. Secondly, smaller droplets, which tend to follow the main air path, pass through the metal foam where they ideally should impact and coalesce on the material filaments and drift radially outwards, by the action of centrifugal forces. Although these devices have high separation efficiency, it is important to understand how these systems work to continue to improve separation and droplet capture. One approach to evaluate separation effectiveness is by means of Computational Fluid Dynamics. Numerical studies on breathers are quite scarce and have always employed simplified porous media approaches where a momentum sink is added into the momentum equations in order to account for the viscous and/or inertial losses due to the porous zone [1]. Furthermore, there have been no attempts that the authors know of to model the oil flow inside the porous medium of such devices. Normally, breathers employ a high porosity open-cell metal foam as the porous medium. The aim of this study is to perform a pore-level numerical simulation on a representative elementary volume (REV) of the metal foam with the purpose of determining its transport properties. The pore scale topology is represented firstly by an idealized geometry, namely the Weaire-Phelan cell [2]. The pressure drop and permeability are determined by the solution of the Navier-Stokes equations. Additionally, structural properties such as porosity, specific surface area and pore diameter are calculated. The same procedure is then applied to a 3D digital representation of a metallic foam sample generated by X-ray tomography scans [3]. Both geometries are compared against each other and experimental data for validation. Preliminary simulations with the X-ray scanned model have tended to under predict the pressure drop when compared to in-house experimental data. Additionally, the few existing studies on flow in metal foams have tended to consider laminar flow; this is not the case here and this also raises the question that Reynolds-averaged turbulence models might not be well suited to flows at such small scales, which this paper considers.

Compressor Instability Active Control via Closed-Coupled Valve and Throttle Actuators

2015 ◽  
Vol 32 (3) ◽  
Author(s):  
Hanlin Sheng ◽  
Wei Huang ◽  
Tianhong Zhang ◽  
Xianghua Huang
Keyword(s):  
Numerical Simulation ◽  
Active Control ◽  
Control Strategy ◽  
Simulation Analysis ◽  
Axial Flow ◽  
Stable Operation ◽  
Compression System ◽  
Control Gain ◽  
System States ◽  
Aero Engines

AbstractActive control techniques are widely researched to expand the stable operating range of axial flow compressors in aero-engines. First, an active controller using closed-coupled valve as actuator has been analyzed using numerical simulation. Analysis results showed that the stability of the controller is affected by system states under large B-parameter of compression system and need a larger control gain besides. Second, using closed-coupled valve and throttle as actuators simultaneously, a novel active control strategy has been proposed. Throttle feedback control is used to decrease the nominal B-parameter of compression system to improve control performance of closed-coupled valve controller. Lastly, numerical simulation has been carried out to evaluate the proposed control strategy. Simulation results showed that the novel controller extends the stable operation range of compression system greatly.

Broadband noise propagation in a Pekeris waveguide

1986 ◽  
Vol 79 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Marcio L. Vianna ◽  
W. Soares‐Filho
Keyword(s):  
Broadband Noise ◽  
Noise Propagation ◽  
Pekeris Waveguide

A Mechanism of Low Subharmonic Response in Rotor/Stator Contact—Measurements and Simulations

2002 ◽  
Vol 124 (3) ◽  
pp. 350-358 ◽  
Author(s):  
Go¨tz von Groll ◽  
David J. Ewins
Keyword(s):  
Numerical Simulation ◽  
Rotating Machinery ◽  
Squeeze Film ◽  
Vibration Frequencies ◽  
Interaction Dynamics ◽  
Squeeze Film Dampers ◽  
Rotor Stator Interaction ◽  
Subharmonic Response ◽  
Subharmonic Vibration ◽  
Aero Engines

There are a variety of abnormal running conditions in rotating machinery that lead to rotor/stator interaction dynamics which, in turn, have a range of effects associated with them. One of these effects is steady vibration response at frequencies which are different from the excitation. This paper describes a mechanism of generating subharmonic vibration frequencies in both numerical simulation and measurements, which are obtained from a study of the relatively new problem of “windmilling imbalance” in aero-engines. What is different from other nonlinear systems with, say, clearance or squeeze film dampers, is the richness of the frequency spectrum.

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