|Department||Environmental and Applied Fluid Dynamics|
|Deadline||July 31, 2018|
PhD thesis with CIFRE financial support, jointly sponsored by the company Chpolansky, the von Karman Institute (VKI) and the Laboratoire d’Acoustique de l’Université du Maine (LAUM)
Chpolansky, company specialized in the field of industrial vanes, Marcoussis (France), http://www.chpolansky.fr/.
von Karman Institute for Fluid Dynamics (VKI), Environmental and Applied Fluid Dynamics, Brussels (Belgium), https://www.vki.ac.be/.
Acoustics Laboratory of Le Mans University (LAUM), UMR CNRS 6613, Le Mans (France), http://laum.univ-lemans.fr/fr/index.html.
C. Pézerat (supervisor), C. Shram (co-supervisor),
F. Gautier (co-supervisor), F. Cartier (industrial advisor).
The research activities will be mainly carried out at the von Karman Institute (near Brussels) and on the premises of the company Chpolansky (Marcoussis). Short missions are foreseen in Le Mans.
After acceptation of the application by ANRT (up to three months after submission of the CIFRE application).
the onset of fluid leakages (gaseous, liquid or diphasic) in industrial piping is causing important financial costs due to the loss of material, to safety issues related to explosion hazards and pollutant dispersion, and constitutes a serious problem when toxic chemicals are lost into the environment. The sectors of activity that are concerned by vane leakage issues are numerous : nuclear energy production by pressurized water reactors, (Boulanger, 1993 ; Lee et al., 2003), natural gas transport (Meng et al., 2012), the automotive sector with the rise of hydrogen powerplants (Dubois, 2011), the oil sector, and the companies or municipal services in charge of the drinking water distribution (Muggleton et al., 2002 ; Beck et al., 2005). Chpolansky has developed a system based on the measurement of the Acoustic Emissions (AE) produced by a leaking flow (gaseous, liquid or diphasic). The AE are measured by means of piezoelectric sensors, and data processing permits assessing whether a vane component is leaking or not. The objective of this PhD thesis is to upgrade this technique in order to obtain a quantitative estimation of the leakage flow, still based on non-intrusive measurements of the vibrations of the duct wall.
a leakage is a jet flow induced by a difference of pressure across an orifice. The turbulence that develops in the jet flow is causing both hydrodynamic and acoustic pressure fluctuations on the inner wall of the surrounding pipe (Lecoq, 2014). The two kinds of pressure fluctuations are inducing loads with different levels and different spatial structures, and their respective contribution to the wall vibration depends on the type of leakage and mechanical properties of the duct. A thorough understanding of the excitation field and of its coupling with the structural response of the pipe is thus necessary in order to achieve a quantitative exploitation of the vibration signal measured by the piezoelectric sensor.
Experimental campaigns will be conducted in order to support the abovementioned activities, where the flow and geometrical parameters – such as the absolute pressures, the aperture geometry, the Reynolds and Mach numbers, etc. – will be varied under controlled laboratory conditions. A test bench comprising a compressed air line with different calibrated orifice components and the necessary instrumentation to measure the operating conditions, is being assembled at the von Karman Institute. The research instrumentation foresees microphone arrays for the modal decomposition of the acoustic field, hot wire anemometry and Particle Image Velocimetry for the characterization of the turbulent jet flow, and piezoelectric sensors for the vibration measurements. Those detailed experiments will complement measurements carried out on two other test rigs: one facility on the premises of Chpolansky in Marcoussis (Rondeau et al., 2018), and another one located in the installations of CETIM in Nantes. Moreover, measurements performed on industrial sites will further complement the laboratory databases and permit assessing the industrial relevance of the latter, considering the background noise that is inherent to an operating industrial plant in particular.