AERIALIST completed the first toolchain loop assessment !

From modeling and design to manufacturing and testing …

The aeroacoustic test of the AERIALIST metamaterials at Bristol

Aeroacoustic measurements of the metamaterial treatments developed in the EU H2020 AERIALIST project. The tests include near-field and far-field flow and noise measurements for a ducted-flow and a flat plate. The metamaterial treatments are designed by Roma Tre University, KTH and the University of Bath and manufactured by Trinity College Dublin.

More experiments are planned for the second and third year of the project for more novel metamaterials developed by the AERIALIST team.

Manufacturing

AERIALIST has reached excellent progress on the development of the 3D printed materials. Nine cubes of 8000 nano-metric cells have been manufactured simultaneously on the ProX DMP 200.  Each production run of 9 cubes requires 30 hours of machine run time with 2 hours of setup and 4 hours of cleaning per run. Cells are made of Cobalt-Chrome powder for a total of ~100g of powder for cube.

 

Theoretical model

Taylor transformations for MM convective design have been considered in the methodological approach to modify the design of an existing MM based device, to take into account the effect of a background flow.

Indeed, it has been widely demonstrated that the aerodynamic convection deeply affects the acoustic response of statically-designed MM, often completely destroying the desired meta-behavior.

 

The figure shows the effect of the Taylor correction on the cloaking efficiency of a cylindrical device at M∞ = 0.35

The theoretical work led to a reinterpretation of the aeroacustic governing equations in a space-time view-point.

This reinterpretation will offer a deeper insight into the mechanism of propagation of noise in the presence of a background flow which is of primary importance in the analysis of the response of unconventional materials.

The analytical tools of the Minkowskian and Lorentzian differential geometries can be effectively used in the design of metamaterial devices based on coordinate transformation including in the presence of background aerodynamics.

Pictures show the streamlines of a potential flow around a rotating cylinder (left) and the corresponding value of the Ricci scalar measuring the space-time curvature (right).

Numerical simulations

The use of the hydraulic radius-based method for the approximated modelling of thermoviscous losses, has been applied, showing an interesting agreement with full direct simulations.

Such an approach will effectively impact on the simulation costs, when the assessment of thermoviscous losses is required.

In the effort to reduce the costs of simulations, partner KTH developed a technique to obtain an equivalent solid model from an an/isotropic Kelvin cell structure.

The picture shows the displacement for both the Kelvin cells structure and the equivalent solid.