Ongoing projects
CHyCAgO = Comportement Hydraulique en cuve agitée optimisée
In the frame of the LEDITH research programme on multiphase flows, the literature review performed previously on slurries led to the second phase of the programme consisting in an experimental study of the flow behavior in a stirring tank to provide an experimental database for CFD validation. This study is divided in three work packages; a literature survey on stirring tank to allow a proper design of the facility, the construction of the experimental facility, and several measurement campaigns consisting in stereo-PIV measurements of a single-phase flow as well as multiphase flows (solid - liquid).
Experimental characterization of straw jets
This study is experimentally investigating the flow pattern in the chute of a straw blower machine. The previous phase of the study investigated only the air flow using PIV. This next phase is using the LS-PIV technique from high-speed images of the straw jet leaving the blower to determine the velocity field of the flow, including the straw. Several speeds of the blower machine, but also two types of straw and different times during the blowing of a straw bundle were investigated. The LS-PIV analysis shows a good reproducibility of the measurements, as well as an influence of the straw type on the flow. The flow stays constant with time during the blowing of a bundle, except at the end of the bundle, where the flow will see a large velocity distribution.
Past projects
Slurry flows : Literature survey
A state of the art of slurry flows has been performed by the von Karman Institute. This study focused on slurries with solid particles in liquid, but also solid particles in gas in the case of fluidized bed. The study focused on the typical industrial areas where slurries are encountered; going from pipelines to pharmaceutical or food processing industry, showing emerging domains like phase change slurries or ice slurries. The study also investigated and compared correlations to model transitional velocities between flow regimes, pressure losses or the slurry viscosity. Finally, the study made an inventory or existing measurement techniques for particle size distribution, pressure loss, viscosity, flow rate, or liquid and solid velocities. For each measurement area, the different techniques were detailed and compared.
Experimental Characterization of Straw Jets using PIV
This study will experimentaly investigate the flow pattern in the chute of a straw blower machine using Particle Image Velocimetry (PIV). A test section identical to the industrial chute will be built in transparent material and will be sent to CETIM to be mounted on an actual straw blower machine. The measurements will focus on three vertical sections of the chute, locate on the central axis; the firs at the entrance of the chute, the second in the middle and the last at the chute exit. These three section will be measured for two rotating speeds and three obstructions of the entrance which will simulate the straw accumulation at different moments.
Prediction of low-speed fan trailing-edge noise based on RANS and on scale resolved simulations
This work compares the prediction of the broadband trailing-edge noise emitted by a four-bladed low-speed ventilation fan obtained with different computational approaches. The objective of each approach is to compute the spectrum of the wall pressure fluctuations close to the trailing-edge, which is an input to Amiet's theory for the computation of the far field noise spectrum. The wall pressure spectrum can be computed by applying Panton and Linebarger's theory to boundary layer data extracted from a time-averaged simulation, or it can be obtained directly by frequency analysis of a scale resolved simulation. The results of both kinds of computation are compared with the measurements taken on the same fan. A better correspondence with the experimental data has been obtained by using a Scale Adaptive Simulation (SAS) rather than a RANS flow solution.
Far field sound power level spectra, third octave average
Experimental Investigation of Cavitation in a Safety Relief Valve
This study focused on the investigation of cavitation and its main consequence in the normal operation of a safety relief valve. The experiments were performed on the BECASSINE facility using a transparent model based on API 1 1/2G3 valve. Precise optical measurement techniques were applied to locally characterize the flow topology during cavitation.
High speed visualization allowed to qualitatively observe the flow pattern and the inception of liquid vaporization. Particle tracking suggest the vapor bubbles are formed in the core of vortices detached from the shear layers attached to the valve. These structures promote low pressure region allowing liquid vaporization.
Particle Image Velocimetry (PIV) technique was also applied to extract velocity fields in single phase and cavitating flow conditions. PIV confirms the existence of a submerged jet downstream the minimum section characterized by two non symmetric shear layers at its sides.
REFERENCE:
Jorge Pinho, Experimental Investigation of Cavitation in a Safety Relief Valve using water. Extension to Cryogenic Fluids, PhD Thesis, Université Libre de Bruxelles, Ecole Polytechnique de Bruxelles / von Karman Institute for Fluid Dynamics, 27 April 2015, ISBN 978-2-87516-089-8 - Thesis available on demand at This email address is being protected from spambots. You need JavaScript enabled to view it.
Experimental Characterization of Straw Jets
This study used a non-intrusive experimental technique to characterize the dense particle laden jet flow produced by straw blowers machine. The experimental set up consists of a straw blower machine, a white background tarp and a color video camera filming the straw jet over a twelve meter test section, in daylight conditions. The technique is based on an image processing routine to detect and track straw particles from the video sequence. In particular, the processing combines two segmentation techniques: 1) a color segmentation, using k-means clustering in the CIElab color space and 2) an adaptive background subtraction, using Eigen-Background decomposition. For a set of four test cases, the straw jet trajectories obtained were complemented –and validated– with the measurement of straw distribution at the ground using a mesh of panels.
