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Technical Paper

Experimental Investigation of High Speed SLD Impact

This paper proposes an experimental investigation of fast impinging large droplets in non-icing conditions. Two main aspects of the impact event are analyzed and discussed: the impact dynamics as a function of the surface nature and the deposition rate of the liquid on the impingement surface for various conditions. The data has been recorded and characterized at ambient pressure and a temperature of the air between 5 and 10°C using a vertical wind/droplet tunnel. To avoid the droplets evaporation the relative humidity was controlled. The morphology of impact was studied by backlighted imagery and quantitative results were obtained by image analysis. The deposition rate was obtained weighting the water accumulated on the impingement plate. Examination of splashing events images obtained on a clean surface and on blotter paper shows important differences in terms of secondary drop generation.
Technical Paper

A Penalization Method for 2D Ice Accretion Simulations

Numerical tools for 3D in-flight icing simulations are not straightforward to automate when seeking robustness and quality of the results. Difficulties arise from the geometry and mesh updates which need to be treated with care to avoid folding of the geometry, negative volumes or poor mesh quality. This paper aims at solving the mesh update issue by avoiding the re-meshing of the iced geometry. An immersed boundary method (here, penalization) is applied to a 2D ice accretion suite for multi-step icing simulations. The suggested approach starts from a standard body-fitted mesh, thus keeping the same solution for the first icing layer. Then, instead of updating the mesh, a penalization method is applied including: the detection of the immersed boundary, the penalization of the volume solvers to impose the boundary condition and the extraction of the surface data from the field solution.
Technical Paper

PEGASE - A Robust and Efficient Tool for Worst-Case Network Traversal Time Evaluation on AFDX

Avionics systems distributed on AFDX networks are subject to stringent real-time constraints that require the system designer to have techniques and tools to guarantee the worst case traversal time of the network (WCTT) and thus ensure a correct global real-time behavior of the distributed applications/functions. The network calculus is an active research area based on the (min,+) algebra, that has been developed to compute such guaranteed bounds. There already exists several academics implementations but no up to date industrial implementation. To address this need, the PEGASE project gathers academics and industrial partners to provide a high quality, efficient and safe tool for the design of avionic networks using worst case performance guarantees. The PEGASE software is an up-to-date software in the sense that it integrates the latest results of the theories, in tight cooperation with academics researchers.
Technical Paper

EXTICE: EXTreme Icing Environement

Recent aircraft incidents and accidents have highlighted the existence of icing cloud characteristics beyond the actual certification envelope defined by the JAR/FAR Appendix C, which accounts for an icing envelope comprising water droplets up to a diameter of 50 μm. The main concern is the presence of SLD (Supercooled Large Droplets), with droplet diameters well beyond 50 microns. In a previous European-funded project, EURICE, in-flight icing conditions and theoretical studies were performed to demonstrate the existence of SLD and to help characterize SLD clouds. Within the EXTICE project the problem of SLD simulation is addressed with both numerical and experimental tools is being addressed. In this paper the objectives and main achievements of the EXTICE project will be described.
Technical Paper

New Investigations of the Mechanisms of Lightning Strike to Radomes Part I : Experimental Study in High Voltage Laboratory

The main purpose of the experiments described here is the analysis of the mechanisms of radome protection with lightning diverters of various types and sizes. A high voltage arrangement and associated diagnostics have been implemented to perform a quantitative study of the inception and propagation mechanisms of the corona and leader discharges that precede the final breakdown. It is shown that ambient humidity plays a significant role on the discharge process and that the nature of the discharge initiated from the strip is very different depending on the strip type. Segmented strips are more likely to allow energetic discharges to propagate from an internal antenna leading to radome puncture.
Technical Paper

A New Contamination Analysis Software

This paper describes the new analysis software for the contamination modelling and outgassing / vent analysis, which has been developed under ESTEC contract by HTS and ONERA. A major part of the software enhancements have been dedicated to the improvement of the algorithms describing the physical processes involved in outgassing and contamination of species in orbit conditions. However, this paper concentrates on additional aspects of the new software tool, which are of interest for space environment analysis software development in general and the thermal analysis community in particular: The use of commercial software packages for the generation of the discrete model geometry and result visualisation. The interfacing possibilities of the software tool with thermal analysis tools.
Technical Paper

ASTRE - A Highly Performant Accelerometer for the Low Frequency Range of the Microgravity Environment

This paper describes the microaccelerometer ASTRE, developed as Laboratory Support Equipment of Columbus, to monitor the residual microgravity disturbance level in the very low frequency range. ASTRE will be integrated in the already flown Microgravity Measurement Assembly (MMA). The paper recalls the microgravity environment which is required on-board Columbus and shortly describes expected discrepancies between the requirements and the predicted, more noisy, situation.