Windshields for PU probes

The industrial partner Microflown Technologies designs and produces PU probes, which are able to measure particle velocity and acoustic pressure fields simultaneously, are sensitive to the effect of wind, since they are based on thermal transducers and hence highly dependent on the variations of thermal flow velocity. Objectives of this research project are the mathematical modelling and numerical simulation of thermo-acoustic coupled Systems (involving PU probes, the compressible fluid in the presence of flow, and the multilayer windscreen). The numerical results will play a key role in the design of novel windscreens to mitigate the flow effects on the measures of acoustic probes.

Figure 1: Scattering field of a plane wave impiging the PU device with a porous wind shield.

The present project is part of the European project ROMSOC (an MSCA European Industrial Doctorate programme). More precisely, since the wind-shield enclosures generate complex acoustics fields inside (see [1] for more details), three different approaches will be analysed by solving numerically the following coupled problems:
(A) Modelling and numerical simulation of the three dimensional coupled acoustic behaviour of a multilayer system consisting in the combination of waterproof fabrics with open porous foams. Novel effective structural-acoustic models will be developed for the structural elements and the sponge layer (see [2])
(B) Modelling and numerical simulation of the three dimensional coupled thermal-acoustic behaviour of a multilayer structure composed of metallic micro-perforated screens surrounding the USP probe. The characterization of the mechanical impedance of this protected screen will be computed in the presence of flow.
(C) Modelling and numerical simulation of the three dimensional coupled thermal-acoustic behaviour of micro-machined wind-shields consisting in a twolayer structure (a nano-perforated thin foil glued to a silicon substrate where the device wires are lying). The turbulence flow around the micro-machined transducer will be characterized. In addition, since the shape of the structure around the sensor can improve the behaviour under flow noise and weak signals, different shapes around the sensor will be tested and compared in different SNR scenarios.

References

[1] Ashwin S. Nayak
Mathematical Modelling and Numerical Simulation of Coupled Acoustic Multi-layer Systems for Enabilng Particle Velocity Measurements in the Presence of Airflow
Phd thesis in mathematical modelling and numerical simulation in engineering and applied science, Universidade da Coruña, 2021. Advisors: D. Fernández Comesaña (Microflown Technologies), A. Prieto.
[2] A. Nayak, A. Prieto, D. Fernández-Comesaña
Model coupling for acoustic sensors in layered media
14th World Congress on Computational Mechanics (WCCM) ECCOMAS Congress 2020,11–15 January 2021.