A Wavelet Transform to Detect the Fluid Separation with Flexible Micro-sensor Array

In order to make the location of separation point of the boundary layer of the air flow measurements easier and more accurate, a very small sensor array has been constructed. MEMS play an important role for studying gaseous or liquid fluid flows experimentally due to device dimensions on the μm-scale. Based on the well-established principle of thermal anemometry, an array of hot-film anemometers on a flexible polyimide substrate was developed. Supplied with a dc electrical current, each sensor acts as a hot wire on contact with the fluid under study. Wind speed is then measured by detecting the resistance variations caused by the thermal transfer from the heated layer to the ambient atmosphere. A wavelet transform based data acquisition system has especially been designed so as to collect the wind speed measurements arising from this kind of hot wire transducer. The integrated silicon sensors have been experimented within a wind tunnel for air speed ranging from 0 to 40 m/s. Compared with the Computational Fluid Dynamics (CFD) simulations result, the sensor array can usefully be employed as fluid separation detection system.