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Reference : UMR8201-JOSBRO-004
Workplace : VALENCIENNES
Date of publication : Monday, April 05, 2021
Scientific Responsible name : Laurent KEIRSBULCK
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Thesis topic n°1 - Emission and visualization of brake particles - Application on a reduced scale braking bench integrating representative flow conditions
The thesis work will consist of implementing an experimental device to study the emission of brake particles on a test bench integrated into a wind tunnel. The objective is to be able to predict the propagation of particles in the near environment from devices measuring their concentration in the air in real time and from PIV measurements characterizing their displacement through velocity field maps. The implementation of these experimental techniques by the PhD student around the braking device should allow to:
• Measure the concentration of particle emissions in the vicinity of the lining application device and in the underbody air stream,
• Evaluate the influence of braking conditions on particle dynamics and correlate with real-time counting devices,
• To provide particle emission input data for numerical studies on diffusion (link with Thesis n°2): quantity, size, density, velocities, particle trajectories,
• To define the most relevant capture points for the design of an on-board device (in conjunction with industrial partners),
Work carried out and means used:
• Sizing, design, production and validation of a small-scale braking bench for carrying out braking tests in a test section, with controlled air flow speed. This braking bench is also intended to be used in:
o Thesis n°2, for the validation of the simulated simplified real case;
o Thesis n°3, for the study of the optimization of the braking/traction functions for the purpose of reducing emissions.
• Definition of a measurement protocol using laser tomography (illumination, acquisition speed) with post-processing (PIV: Particle Image Velocimetry).
• Carrying out friction tests on the disc/lining pair(s) according to the braking conditions.
• Identification of velocity fields of particles emitted during friction in the vicinity of the disc/lining pair (by PIV post-processing).
• Comparison of the visualizations with on-line counting measurements at several points.
• Feedback on the choice of measurement points as defined by the protocol defined with the academic and industrial partners of the BREAQ project.
• To guide the industrial partners (ALSTOM) in the choice of the most relevant collection points for the design of an on-board device on a train.
This thesis is proposed by LAMIH as part of the BREAQ project. LAMIH UMR CNRS 8201 (Laboratory of Industrial and Human Automation control, Mechanical engineering and Computer Science) is a joint research unit between Université Polytechnique Hauts de France (UPHF) and National Centre for Scientific Research (CNRS). The new LAMIH is divided in four scientific departments clearly identified: Automation and Control, Mechanical Engineering, Computer Science and Human and Life Sciences (SHV).
The BREAQ project, supported by ADEME, and bringing together several academic and industrial partners including ALSTOM, aims to reduce braking particle emissions at source and to predict the diffusion of these particles in the environment in order to develop efficient capture solutions. Within the framework of this project, 3 thesis subjects are proposed by LAMIH.
Air quality is a major public health issue. According to the World Health Organization, by reducing air pollution levels, countries can reduce the burden of disease from stroke, heart disease, lung cancer and respiratory diseases.
Rail transport is rightly considered to be a sustainable mobility solution with low greenhouse gas impact and a low contributor to air pollutant emissions (NOx, SO2, VOC & PM10). Nevertheless, several studies highlight that pollutant concentrations in underground rail enclosures should be considered of concern. In some cases, concentrations of fine particles can be ten times higher indoors than outdoors. In this context, the reduction or mitigation of emission sources linked to braking, the main contributor in the railway sector, represents a major issue for human health. Previous work carried out at LAMIH (Charlene Octau thesis, November 2019) has shown that the conditions of use of mechanical braking influence the dimensions of the particles emitted and has made it possible to develop the bases necessary for the numerical simulation of the diffusion of particles in the immediate environment.
Profile of the candidate:
• A degree in mechanical engineering or equivalent with a profile as an experimenter in flow studies. Knowledge of PIV is desirable.
• Knowledge of tribology applied to braking is also desired.
• The thesis work will be mainly experimental: development of a specific test method, setting up the associated metrology, carrying out and analyzing tests, etc.
• Pragmatic scientific approach and good perception of the economic context.
• Excellent oral and written communication skills, in French (fluent) and English (B2).
• Desired qualities: innovative spirit, strength of proposal.
• The thesis work will be done in collaboration with the project partners (ALSTOM, FLERTEX, LAMCUBE laboratory, SAGE laboratory). The candidate must have good communication skills and an open mind in order to be able to dialogue and capitalize on their experiences.
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