Abstract
Turbulence is an important phenomenon present in many flows, whether natural or industrial, and is characterized by a wide variety of spatial and temporal scales. It is therefore of particular interest to develop metrological means adapted to the measurement of physical quantities such as velocity and temperature fluctuations to better understand and characterize it.In the context of aerodynamic measurements, the sensors most commonly used today are the hot wire anemometer for velocity measurements and the cold wire thermometer for temperature measurements. However, these two means of measurement have some limitations. Indeed, it has been shown that if the length of their sensitive element is too long compared to the characteristic scales of the flow, then these probes operate a spatial filtering of the smallest scales of turbulence, yet necessary to the complete resolution of this type of flow. Faced with this observation, this thesis work asks the question of the possibility of an improvement of these two metrological means. Because of their limitations, the main improvement considered is the reduction of the size of their sensitive element by relying on micro-fabrication techniques, thus allowing to increase the range of measurable spatial scales in a turbulent flow. Moreover, in the context of the characterization of aerothermal flows, it appears to be of interest to be able to carry out simultaneous measurements of velocity and temperature fluctuations. It is thus envisaged to use the technologies of measurement by hot wire and cold wire to carry out this.This study consists in the development of thermo-resistive micro-sensors allowing to postpone the limit of detection of the small scales contained in a turbulent flow. The first objective is to develop functional probes allowing to realize anemometric or thermometric measurements to then turn to a second objective aiming at developing a sensor of the same type but carrying out these two measurements in a simultaneous way.To reach these objectives, it was first a question of making a relevant choice on the materials used as well as studying different processes of micro-fabrication, in particular of silicon etching. This allowed to realize different geometries of micro-sensor in order to identify the most appropriate for measurements in turbulent flow. In order to quantify their capacity to measure velocity fluctuations, these new sensors were used for turbulent boundary layer measurements, with particular attention paid to the control of the experimental protocol. The results obtained have been compared to different semi-empirical models as well as to measurements performed with classical hot-wire probes. In order to observe the performance of the micro-sensors for temperature measurements, a specific experimental bench has been designed to evaluate their frequency responses. Finally, the first prototypes of micro-probes allowing to realize simultaneous measurements of speed and temperature were tested.