MEMS High Temperature Gradient Sensor for Skin-Friction Measurements in Highly Turbulent Flows

This paper presents and discusses the results obtained with a MEMS (Micro-Electro-Mechanical System) high temperature gradient sensor for time-averaged and fluctuating skin-friction measurements in highly turbulent flows. Designed as a robust wall-mounted suspended hot-wire structure, the micro-sensor was made using conventional microfabrication techniques, compatible with microelectronics for designing integrated smart systems. Successfully implemented into two air wind tunnels, the sensor was tested in a large range of turbulent flows, with mainstream velocities going up to 270 m/s (Mach number of 0.79), which corresponds to the mean velocity of airliner cruise flights. The experiments demonstrated the wide dynamic range of the micro-sensor without reaching its limits. The micro-sensor thereby demonstrated its value for measuring turbulence in aerodynamic applications, being particularly suitable for aeronautics.