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AEROSPATIALE --- AERONAUTICS

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Industrie aérospatiale. --- Lucht- en ruimtevaartindustrie.

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Nowadays, numerical simulation is increasingly used, providing tools to reproduce numerically the behavior of a system and solve engineering problems. In sectors such as aeronautics, this tool is essential with the constant process of improvement at the lowest costs, parts becoming more and more complex.
During take-off and landing, an aircraft is subjected to heavy aeronautic loads. To avoid stalling of the aircraft during these two critical phases, moveable devices located on the wings are used to increase the lift of the plane, such as the slat, located on the leading edge of the wing, and the flap, located on the trailing edge. To adapt to the aerodynamic requirements, the latter is divided into two parts: the inboard flap, next to the fuselage, and the outboard flap, next to the wing tip, joined together by an interflap seal. This project focuses on that part.
Used to maintain the sealing against air between the outboard and inboard flap in order to ensure optimal performances, the seal is heavily loaded when activating the flaps. To fulfil such aeronautical constraints (aerodynamic pressure, displacements, altitude, temperature,…), seals made of reinforced elastomer are necessary. The seals studied in this report are made of two main materials: silicone, allowing huge deformation, and glass fiber reinforcements, increasing the rigidity of the seals.
So far, the development of the design, the stiffness and the manufacturing method of the seal was based on development tests as the material properties of this complex material are not known precisely enough to safely predict the behavior of the structure. The objective of this work is to determine the properties of the different materials (silicone and reinforcement) in order to use the results of the finite element analysis with a higher confidence, with a view to cost and time reduction.
To do so, experimental tests (tension, compression and bending) were performed on test specimens, composed of a silicone matrix and different numbers of reinforcement. The material parameters are calculated by matching numerical results obtained by performing finite element analysis with the experimental results.
Through simulations of the test specimens, linear and nonlinear elastic material laws were found to match the experimental results. The obtained behavior laws are then tested in finite products, two different seal models in this case, to check if there are acceptable and validate them. 
To conclude, appropriate material laws are found to model the behavior of aeronautical seals. Nevertheless, the laws are different according to the type of solicitation, pure tension/compression or bending, and the number of reinforcements inside the silicone matrix. Moreover, the laws can still be refined and improved to increase the precision of the finite element analysis.

Ingénierie, informatique & technologie > Ingénierie aérospatiale

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In the framework of this master thesis, a numerical study has been carried out in order to investigate
the effect of tip geometry on the tip leakage flow and heat transfer features in a unshrouded high
pressure axial flow turbine stage designed by Erhard of the TTM laboratory in Austria. Four different tip profiles were considered,
namely a default flat tip, a modified flat tip, a modified double squealer tip and a modified double
thin squealer tip. The performances of the distinct tip profiles were compared to determine the improvement
in terms of leakage mass flow rate and heat transfer. The computations were carried out
on a single rotor blade with periodic boundary conditions. Grid independence study was performed
in order to determine the adequate mesh to employ for the computations. Turbulence was modelled
with the BSL-RSM model because it provides more advantages than its SST counterpart model. At
the end, it was proven that adoption of a cavity can drastically enhance the aerothermal performances,
that is, providing a decrease in the leakage loss and average heat transfer over the tip.

Ingénierie, informatique & technologie > Ingénierie aérospatiale

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This master thesis will present the multi-disciplinary optimization process of a transonic compressor taking into account a circumferential distorted inlet flow. The initial geometry of the optimization will be the NASA rotor 37, a test compressor that was extensively studied. From experimental data available in the literature, the CFD code used in the optimization process will be validated as well as the procedure used to obtain mechanical responses.

Then, the optimization process will be conducted using MINAMO, a multi-disciplinary design optimization tool of the applied research center Cenaero. This platform is strongly based on surrogate models.The design space of the optimization being defined by the coordinates of the blade's control points, an initial design of experiments will be built, exploring different geometries.

For all the geometries, different mass flows and inlet profiles will be tested to extract enough information about each blade. Several optimizations will be conducted under different aero-mechanical constraints in order to evaluate the possible improvements and the impact of the constraints used.

Ingénierie, informatique & technologie > Ingénierie aérospatiale