Q. Leclère

Q. Leclère
Institut National des Sciences Appliquées de Lyon | INSA Lyon · Laboratory of Vibrations and Acoustics (LVA - EA 677)

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168
Publications
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Publications

Publications (168)
Conference Paper
This paper focuses on the study of broadband shock-associated noise (BBSAN) emitted by the jet of dual-stream aircraft engines in cruise flight conditions. This work builds on past experience of BBSAN-oriented experimental campaigns conducted within Airbus, and on recent progress made on signal processing techniques and source modeling in the liter...
Article
Phase demodulation is arguably the most used technique for the estimation of the instantaneous angular speed from vibration signals measured on rotating machinery. Although phase demodulation offers a straightforward approach to determine accurately the rotation speed of a particular shaft in a rotating machine, it does have strict limitations that...
Article
Full-text available
Aeroacoustic signals, as typically returned by recordings of pressure fluctuations generated by rotating machines, often exhibit a strong contribution of broadband components. The separate analysis of the various sources of broadband noise is important from an engineering point of view as they relate to different physical mechanisms. It is yet tech...
Article
Full-text available
Aeroacoustic signals, as typically returned by recordings of pressure fluctuations generated by rotating machines, often exhibit rich mixtures of tonal and broadband components. The separate analysis of these constituents is important from an engineering point of view, as they relate to different physical mechanisms. This paper is concerned with th...
Article
A Bayesian method to remove correlated noise from multi-channel measurements is introduced. It is based on Bayesian factor analysis coupled with prior but uncertain knowledge of the correlation structure of the noise. This technique is well suited to denoise cross-spectral matrices measured in the frame of aeroacoustic experiments when background n...
Article
Full-text available
The multiple coherence is a spectral analysis tool allowing the estimation of the contribution of several, possibly partially, coherent inputs to one or several outputs. This type of analysis can be conducted using a waterfall substraction approach (Conditioned Spectral Analysis framework) or using an eigenvalue analysis of the input correlation ma...
Article
Full-text available
When performing measurements with wall-installed microphone array, the turbulent boundary layer that develops over the measuring system can induce pressure fluctuations that are much greater than those of acoustic sources. It then becomes necessary to process the data to extract each component of the measured field. For this purpose, it is proposed...
Chapter
The wall pressure measured by an array of flush mounted microphones subject to a flow results from two components. The first one is due to the pressure fluctuations generated by vortices convected by the flow in the turbulent boundary layer developed on the wall, and the second one results from acoustic waves that are emitted by some acoustic sourc...
Article
Full-text available
This paper deals with the dynamic characterisation of plate structures with elliptical orthotropic stiffness properties, using an equivalent thin plate theory using a wave fitting approach. The method consists in projecting the experimentally determined transverse displacement field of a plate on an analytical Green’s function of an elliptical orth...
Conference Paper
This paper investigates the efficacy and reliability of three different state-of-the-art rotation speed estimation techniques on a very large set of experimental vibration data originating from thirty offshore wind turbine gearboxes. The three methods include the multi-order probabilistic approach, the phase demodulation method based on the frequen...
Article
A smartphone is a low-cost pocket wireless multichannel multiphysical data acquisition system: the use of such a device for noise and vibration analysis is a challenging task. To what extent is it possible to carry out relevant analysis from it? The Survishno conference, held in Lyon in July 2019, proposed a contest to participants based on this su...
Article
Full-text available
The aim of this paper is to propose a methodology for identifying the pressure field applied on a laminated composite plate from its measured vibration response. The general framework of this study is the Corrected Force Analysis Technique (CFAT), which was previously used on isotropic plates. This method estimates the spatial derivatives of the eq...
Article
Full-text available
Array measurements can be contaminated by strong noise, especially when dealing with microphones located near or in a flow. The denoising of these measurements is crucial to allow efficient data analysis or source imaging. In this paper, a denoising approach based on a Probabilistic Factor Analysis is proposed. It relies on a decomposition of the m...
Article
Full-text available
This paper presents the modelling and the dynamic characterisation of laminated composite plates and sandwich structures in terms of stiffness and damping. The developments used in this paper are based on the analytical multilayer model of Guyader and Lesueur (JSV, 1978). The model considers linear shear, membrane and bending effects in each layer....
Article
Full-text available
Acoustic beamforming is a technique to measure the sound field and then achieve the localization of the sound sources. It usually works at a high frequency because the size and density of the microphone array are limited. Differing from the traditional beamforming, non-synchronous measurements beamforming can widen the working frequency bandwidth w...
Conference Paper
Full-text available
In the field of experimental aeroacoustics in wind tunnel, the number of existing methods is important and is increasing continuously so that it becomes difficult for Industrials to have a clear view of the respective advantages of each of them and make appropriate choice. Benchmark works are also plentiful and often focus on the performance of the...
Conference Paper
Full-text available
Acoustic imaging technique based on microphone array is limited by the size and density of the array, and the method of the non-synchronous measurements is a way to beyond these constraints. The core problem of archiving the non-synchronous measurements of microphone array boils down to a matrix completion of a block diagonal spectral matrix. In th...
Article
An algorithm based on a hierarchical Bayesian model is introduced to separate sources highly overlapping in time and frequency and observed through correlated references. The method is applied to internal combustion (IC) engine signals with the aim of separating the contributions due to different physical origins. The results are compared to the on...
Data
Instantaneous speed estimation has become a key part of many condition monitoring procedures for rotating machinery. The ability to track the rotational speed of a system is a critical requirement for the majority of vibration-based condition monitoring methods. Information about the speed enables compensating for potential speed variations that wo...
Article
A lightweight numerical method is developed to predict the sound absorption coefficient of resonators whose cross-section dimensions are significantly larger compared to the viscous and thermal boundary layer’s thicknesses. This method is based on the boundary layer theory and on the perturbations theory. According to the perturbations theory, in a...
Preprint
Measured acoustic data can be contaminated by noise. This typically happens when microphones are mounted in a wind tunnel wall or on the fuselage of an aircraft, where hydrodynamic pressure fluctuations of the Turbulent Boundary Layer (TBL) can mask the acoustic pressures of interest. For measurements done with an array of microphones, methods exis...
Article
In a previous work, an attempt was made to give a unified view of some acoustic holographic methods within a Bayesian framework. One advantage of the so-called “Bayesian Focusing” approach is to introduce an aperture function that acts like a lens and thus significantly improves the reconstruction results in terms of spatial resolution, but also of...
Article
Full-text available
Phased microphone arrays have become a well-established tool for performing aeroacoustic measurements in wind tunnels (both open-jet and closed-section), flying aircraft, and engine test beds. This paper provides a review of the most well-known and state-of-the-art acoustic imaging methods and recommendations on when to use them. Several exemplary...
Article
Full-text available
The issue of acoustic source identification has been widely explored in static or quasi-static source contexts, more recently for moving sources, in a wide range of applications. In the case of a passing-by vehicle, the beamforming method is a reference having well-known limitations that deconvolution methods try to overcome. Mostly developed in st...
Article
The paper describes an equivalent source model of acoustic sources from optical measurements using refracto-vibrometry. The acousto-optic effect is used to characterize the acoustic source in a non-invasive manner. The equivalent source model is constructed with a volumic distribution of monopole sources: its radiation should produce an acouto-opti...
Article
Full-text available
In the context of aeronautics, automotive and construction applications, the design of light multilayer plates with optimized vibroacoustical damping and isolation performances remains a major industrial challenge and a hot topic of research. This paper focuses on the vibrational behavior of three-layered sandwich composite plates in a broad-band f...
Article
Full-text available
A new measurement procedure is proposed to assess the airborne sound insulation of a partition under diffuse sound field excitation using mobility measurements combined with a numerical procedure. The advantage of this hybrid approach is that the diffuse acoustic field does not need to be physically created , thus avoiding problems related to the g...
Article
Full-text available
At low frequencies the assessment of the sound reduction index of building elements in the laboratory according to the standard ISO 10140-2:2010 is burdened by a large variation in the measurement results. This is due to the fact that at low frequencies the acoustic field is not sufficiently diffuse. This paper discusses a measurement procedure in...
Conference Paper
Full-text available
The issue of the identification of acoustic sources has been widely treated in static or quasi-static source contexts, more recently for moving sources, in a wide range of applications. The beamforming method is a reference in that situation, but it has well-known limitations, namely a poor resolution at low frequencies which makes it difficult to...
Conference Paper
Full-text available
Acoustic beamforming consists in measuring the sound field by the microphone array and infers the source strength in conjunction with the propagation model. A fundamental limitation of acoustic beamforming is determined by the aperture size of the array and the microphone density. In order to extend the working frequency range of conventional phase...
Presentation
Full-text available
Acoustic beamforming consists in measuring the sound field by the microphone array and infers the source strength in conjunction with the propagation model. A fundamental limitation of acoustic beamforming is determined by the aperture size of the array and the microphone density. In order to extend the working frequency range of conventional phase...
Conference Paper
Full-text available
The use of multichannel measurements is a current practice for source characterization in multiple fields. But common to all experimental approaches is the presence of extraneous noise such as calibration, electronic or ambient noise. However, signals are supposed to be stationary and performing averaging of cross-spectral quantities over several t...
Article
In this paper, the Scanning Laser Doppler Vibrometer (SLDV) is used to measure acoustic pressure in small regions of cavities for the study of acoustical localization. It is shown that this optical method leads to interesting information on localized acoustical modes inside irregular cavities, which are very difficult to observe using conventional...
Conference Paper
Full-text available
The problem of the acoustic sources identification has been widely treated in static or quasi-static source contexts, more recently for moving sources, in a wide range of applications. In the context of source identification from a passing-by vehicle, the beamforming method is a reference that has well-known limitations. Deconvolution methods are u...
Article
Acoustical source reconstruction is a typical inverse problem, whose minimum frequency of reconstruction hinges on the size of the array and maximum frequency depends on the spacing distance between the microphones. For the sake of enlarging the frequency of reconstruction and reducing the cost of an acquisition system, Cyclic Projection (CP), a me...
Article
Full-text available
The problem of localizing and quantifying acoustic sources from a set of acoustic measurements has been addressed, in the last decades, by a huge number of scientists, from different communities (signal processing, mechanics, physics) and in various application fields (underwater, aero, or vibro acoustics). This led to the production of a substanti...
Conference Paper
During the last decades, an emerging interest has been reported on modelling rotating machinery signals as cyclostationary. Several tools, such as the Spectral Correlation Density (SCD) and the Cyclic Modulation Spectrum (CMS) have been proposed, assuming constant or almost constant rotating speed. To overcome this limitation, generalizations of SC...
Conference Paper
Full-text available
Accurate speed estimation is essential for dynamic analysis of rotating machinery; particularly for condition monitoring and operational modal analysis of applications with significant load and speed variation. The wind turbine is such an application. However, a sufficiently accurate tachometer, to keep track of the instantaneous speed, is not alwa...
Article
During the last decades, an emerging interest has been reported on modelling rotating machinery signals as cyclostationary. Several tools, such as the Spectral Correlation Density (SCD) and the Cyclic Modulation Spectrum (CMS) have been proposed, assuming constant or almost constant rotating speed. To overcome this limitation, generalizations of SC...
Conference Paper
Full-text available
Beamforming with a spherical microphone array has become an attractive tool for sound source localization in cabin environments. To provide a reliable localization solution with high performance , the first step is to optimize the array design. In this paper, the spatial resolution and dynamic range of an open spherical array with various microphon...
Conference Paper
Full-text available
In this work, various microphone phased array data processing techniques are applied to two existing datasets from aeroacoustic wind tunnel tests. The first of these is from a large closed-wall facility, DLR's Kryo-Kanal Koln (DNW-KKK), and is a measurement of the high-lift noise of a semispan model. The second is from a small-scale open-jet facili...
Conference Paper
Full-text available
To solve the problem of non-stationary speed conditions in rotating machinery, order tracking has become a popular practice to synchronize the Fourier analysis to the shaft rotation. Being able to estimate the instantaneous angular speed (IAS) accurately, enables analysts to identify machine events linked to the shaft rotation much easier. The IAS...
Chapter
Full-text available
This lecture series deals with a family of sound source localization techniques based on the solution of minimization problems and make an extensive use of the matrix generalized inverse operator. It is separated from more usual techniques such as beamforming and deconvolution algorithms in the sense that all sources are considered at once (and not...
Article
Rotating machines diagnosis is conventionally related to vibration analysis. Sensors are usually placed on the machine to gather information about its components. The recorded signals are then processed through a fault detection algorithm allowing the identification of the failing part. This paper proposes an acoustic-based diagnosis method. A micr...
Article
Full-text available
Most processing tools based on frequency analysis of vibration signals are only applicable for stationary speed regimes. Speed variation causes the spectral content to smear, which encumbers most conventional fault detection techniques. To solve the problem of non-stationary speed conditions, the instantaneous angular speed (IAS) is estimated. Wind...
Article
With the aim of decreasing CO2 emissions, car producers’ efforts are focused, among others, on reducing the weight of vehicles yet preserving the overall vibrational comfort. To do so, new lightweight materials combining high stiffness and high (passive) damping are sought. For panels essentially loaded in bending, sandwich composites made of two e...
Article
The problem of the identification of acoustic sources has been widely treated in static or quasi-static source contexts, more recently for moving sources, in a wide range of applications. Different methods have been developed in this endeavor. In the context of identification of sources from a passing-by vehicle, the beamforming method is a referen...
Article
In order to design vehicles with diminished CO2/km emissions level, car manufacturers aim at reducing the weight of their vehicles. One of the solutions advocated by the automotive engineers consists in the replacement of metallic parts by lighter systems made of polymercomposites. Unfortunately, the numerical simulations set to evaluate the vibrat...
Article
Full-text available
This paper concerns the assessment of the dynamic stiffness of plates using non-contact excitation and non-contact measurements. In particular, a constrained-layer damping sandwich plate is considered, of which the apparent dynamic stiffness as function of frequency is determined. The experimental results compare very well with an analytical model...
Article
This paper presents the content and outcomes of the Safran contest organized during the International Conference Surveillance 8, October 20-21, 2015, at the Roanne Institute of Technology, France. The contest dealt with the diagnosis of a civil aircraft engine based on vibration data measured in a transient operating mode and provided by Safran. Ba...
Article
Full-text available
A Digital Loudspeaker Array (DLA) is an electro-mechanical transductor which receives a numerical signal as input data and allows the analogical conversion directly in the air. We designed PZT actuated membranes in order to obtain the highest acoustic pressure as possible. We built 256-MEMS-membranes DLAs using a generic PZT technology and digital...
Article
Full-text available
This paper presents a new wave fitting approach to estimate the frequency dependent material properties of thin isotropic plate structures from an experimentally obtained vibrational field, exciting the plate at a single point. The method projects the measurement data on to an analytical image source model, in which Hankel's functions are used for...
Article
This paper addresses the problem of in situ calibration of a pin hole-mounted microphone array for in-duct acoustic measurements. One approach is to individually measure the frequency response of each microphone, by submitting the probe to be calibrated and a reference microphone to the same pressure field. Although simple, this task may be very ti...