3 FRIA doctoral fellowships have been granted by FNRS
We are pleased to announce that 3 FRIA doctoral fellowships have been granted by FNRS to PhD candidates enrolled in the VKI PhD program.
FRIA stands for "Fonds pour la formation à la Recherche dans l'Industrie et dans l'Agriculture" and is managed by FNRS (Belgian Scientific Research Foundation for the Fédération Wallonie-Bruxelles).
The candidates who obtained the grant are:
- Gian Luca Gori (supervisor Prof. Tony Arts) - see the abstract below
- Aurelie Bellemans (VKI supervisor Prof. Thierry Magin & ULB supervisor Prof. Alessandro Parente) - see the abstract below
- Alessia Simonini (VKI supervisor Prof. Rosaria Vetrano & ULB supervisor Prof. Pierre Colinet) - see the abstract below
Abstract of Gian Luca Gori
Determination and modeling of the aero-thermal behaviour of a cooling channel
Cooling channels have wide applications, ranging from aeronautics to oil, automotive and nuclear industry. Initially designed with smooth walls, their surface has rapidly been equipped with various obstacles to increase the thermal exchange area and the local mixing. The main objective is to maximize the wall heat transfer while keeping the channel pressure drop as low as possible. The proposed research focuses on an aeronautical application (gas turbines), but is of definite interest to many other fields of engineering. The thermal efficiency of a gas turbine cycle increases with the Turbine Inlet Temperature. The limits are set by the blades and endwalls material resistance against thermal and mechanical loads. Their life time will increase by using efficient cooling techniques. A major contribution to the heat extraction is ensured by forced convection. Although known for a long time, it still has margin for important improvements. The classical CFD codes approaches based on isotropic turbulence and constant Prt models provide limited fidelity. High resolution reliable experimental data are therefore needed for the validation and new modeling purposes. Their actual lack is mainly due to the complexity and availability of measurement techniques and representative facilities.The present research intends to close this gap by looking at the effect of Reynolds, Rotation and Buoyancy numbers. Liquid Cristal Thermography will provide the wall heat transfer distribution whereas Planar or Stereo PIV will furnish the aerodynamic field. The main goal is to provide an explanation of the heat transfer distributions by means of the flow characteristics and hopefully some modeling improvement. Some of these measurements will also be made in rotation to evaluate the effect of this parameter. The final output will allow a detailed explanation of the aero-thermal phenomena as well as a suitable tool for CFD modeling and design procedures.
Abstract of Aurelie Bellemans
SPARK: Simplified PlasmA models based on Reduced Kinetics
The detailed chemistry modeling of plasma flows for ablation phenomena during atmospheric re-‐entry and solar physics is a very complex problem. This work proposes to reduce this complexity by developing reduced chemistry models with mathematics-‐ and physics-‐based reduction techniques. Uncertainty quantification on the rate coefficients will be used as a sensitivity analysis for retrieving the most important reactions within the mixture. Analyzing the system dynamics will give an overview of the important reaction variables that can be used as a base for the reduced model. By expressing the system in its entropic variables one can carry out a singular perturbation analysis to project the system on its slow varying base. The reduction can consequently be carried out on this slow manifold. Also Rate-‐Controlled Constrained Equilibrium (RCCE) will be investigated as a physics-‐based reduction method. Manifold Generated Principal Component Analysis (MG-‐PCA) has already been studied during the past year. This method has successfully been implemented on a one-‐dimensional code simulating argon plasma shock tube experiments. A reduction of 36% has been obtained with the global formulation of the method. MG-‐local-‐PCA has also been implemented and verified. An impressive reduction of 56% has been obtained with this local method. To complete the work, MG-‐local-‐PCA will be coupled with non-‐linear regression on the source terms. PCA will also be carried out on entropic variables to couple the method with a physics-‐based technique. The reduced model will be implemented as reduction module in MUTATION++, a transport, thermodynamics and chemistry database for plasma flows, developed at VKI. The module will be coupled with the ablation code of VKI and validated with Plasmatron experiments. It will also be linked with the flow solver of A. Alvarez Laguna for solar physics applications, and validated with observational data of NASA Ames.
Abstract of Alessia Simonini
Dynamic sloshing investigation by means of non intrusive measurement techniques
The motion of the free liquid surface inside its container is called “sloshing” and it is strongly affected by external excitations. The understanding and the prediction of this particular motion is of great concern in many fields. Indeed, the motion of liquids inside containers can refer to embarked reservoirs filled of fluid, cooling liquids in systems subjected to earthquakes or propellants inside tanks.This phenomenon can have an infinite number of natural frequencies depending on shape and rigidity of the container, kind and quantity of liquid. In literature, analytical and mechanical analogies are widely used to model this phenomenon, whereas numerical simulations are still far from the desired reliability. Experimental results are mainly obtained by means of intrusive measurement techniques, while few works are present in literature concerning the use of non-intrusive techniques applied to sloshing experiments. The main goal of this project is to select and develop non-intrusive experimental techniques in order to provide a complete characterization of the sloshing phenomenon in terms of velocity field, free surface behavior and contact angle investigation. In a first phase of the project, a case study will be selected in terms of geometry of the container and the kind of external excitation. The selection will be driven by the most common case of interest for industrial application and by the availability of a widely accepted analytical solution existent in literature. The measurement techniques will be developed and applied to the case study, evaluating their performances in the characterization of the velocity field, free surface behavior and contact angle determination. Finally, the application of the selected non-intrusive techniques to a real sloshing case of interest for industries will be tested. In particular, the chosen techniques will be applied to cryogenic fluids having physical properties similar to real space propellants. Moreover, tests performed with water will be used to validate existing numerical codes developed in the framework of Nuclear Power Reactor Safety. In conclusion, this project aims to both develop new experimental tools for the characterization of sloshing and to provide an accurate database for the verification and validation of numerical simulations.