Experimental characterization of anti-icing system and accretion of re-emitted droplets on turbojet engine blades

In the framework of STORM, a European project dedicated to icing physics in aircraft engines, a cascade rig representative of an anti-iced engine inlet was tested in icing conditions. This mock-up integrates two rows of vanes, the upstream one being anti-iced using an Electro-Thermal Ice Protection System (ET-IPS). Experimental tests were performed to reproduce the following phenomena: runback water and droplet re-emission from anti-iced vanes, and accretion of re-emitted droplets on downstream vanes. A complete experimental database was generated, including the characterization of ice accretion shapes, and the characterization of electro-thermal anti-icing system (power limit for apparition of the runback water or ice accretion). In the current study, these data are compared to droplet trajectory simulation and ice accretion simulation results, for validating icing tools in engine environment. Influence of one-step and multi-step approaches have been investigated

Operating characteristics of a prototype high energy gamma-ray telescope

The field of gamma-ray astronomy in the energy range from ten to several hundred MeV is severely limited by the angular resolution that can be achieved by present instruments. The identification of some of the point sources found by the COS-B mission and the resolution of detailed structure existing in those sources may depend on the development of a new class of instrument. The coded aperture mask telescope, used successfully at X-ray energies hold the promise of being such an instrument. A prototype coded aperture telescope was operated in a tagged photon beam ranging in energy from 23 to 123 MeV. The purpose of the experiment was to demonstrate the feasibility of operating a coded aperture mask telescope in this energy region. Some preliminary results and conclusions drawn from some of the data resulting from this experiment are presented

Stratégie de grille conforme octrée intersectées pour les Applications aux calculs Aéroacoustiques de LAGOON, Modèle de train d'Atterrissage, utilisant le Flow Solver CEDRE non structuré

International audienceAircraft noise is a societal concern and landing gears contribute significantly to the generated noise in approach and landing configurations. Landing gears are characterized by their complex geometry and numerous works have been carried out to develop and validate aeroacoustics simulations to predict the associated noise. Most of them associate a time resolved flow solution, to capture the acoustic sources, to an acoustic computation, to estimate the resulting far field noise. Due to the geometric complexity, unstructured grids are required and may necessitate meticulous work to optimize. In this context, Lattice Boltzmann Methods (LBM) have become popular as they propose to combine automatic grid generation and high CPU efficiency and produced remarked results. The automatic grid generation is facilitated by the use of advanced wall models that do not require resolution of complex details of boundary layer flow, ranging from attached to detached regimes, that are produced by the complex geometries and flow environment of landing gears. Navier-Stokes (NS) solvers on the contrary rely on precise boundary layer solution that require complex grids, even in the unstructured approach, to handle the attached boundary layer regimes, that require strong grid anisotropy, as well as detached regimes and their trailing flow, that require grid isotropy. The grid construction work can therefore become a complex process. The simplification of this process is then an important challenge for industrial applications. The present work details a multi-year effort at ONERA in that direction

Some HPC challenges for multi-physics extended CFD computations

International audienceAs the numerical simulations become more and more used for prediction and analysis of complex non stationary flows and as the computer architectures steadily evolve towards massively parallel, there is a real need to adapt computational codes to make them ready for intensive use in a HPC cluster environment. In the same time there is a strong tendency in the CFD community to enlarge the scope of computations by associating and possibly by directly coupling different physics in a unique computation. Such multi-physics computations open the way to needed sizing, analysis and optimization of complex systems. Common examples are fluid/solid interactions (conjugate heat transfer, aeroelasticity, aeromechanics), aeroacoustics, two-phase flows, combustion. This reality puts severe demands especially for multi-physics codes that are at stakes to provide HPC performances while addressing several physics that are discretized on the same computational domain. The CEDRE code developed at ONERA as the reference code for energetics and propulsion is particularly concerned by these challenges. The present version CEDRE 5.1 is already daily used on clusters with thousands cores with a very good scalability

Study of Entropy Noise through a 2D Stator using CAA

International audienc

Analysis of ballistic waves in seismic noise monitoring of water table variations in a water field site: added value from numerical modelling to data understanding

International audienc

Portability and parallelism on a cray computer

Tire de : IMSL user group Europe conference, Paris (France), april 17-19, 1991SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1991 n.33 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc