Résumé: Air flow visualization systems are very useful tools to design aerodynamic efficient systems. The aim of the project is to design a system measuring velocity field of an air flow. The system has to acquire autonomously air velocity vectors in a user-determined volume.
The invasive pneumatic probe is a cheap tool to acquire information about flow fields. However this kind of probe can impact the visualized flow and gives only local flow information. These probes work with air pressure sensors. These sensors allows to determinate locally the air velocity magnitude flowing one direction. By coupling several of these sensors each oriented in different direction, the direction of the flow can be locally determined. This is the main idea of the Multiple Hole Probe (MHP).
A calibration process can compensate the defect in shape of the MHP and gives the equation linking the pressure of holes and the velocity vector information. Accuracy and valid range are conditioned by the calibration algorithm. Our algorithm allows to have a range about sixty degrees for an accuracy of one degree.
The reduction data algorithm is an important step because it determines the calculation time for the velocity vectors from the air pressures. The created algorithm provides the angle and the magnitude of the vector almost instantly.
Finally the visualization of the data can be performed in several way. The streamlines is often used because of its clarity and its ease of understanding the behaviour of the fluid. The LIC representation gives a more dense representation of the flow so mental interpolation is not anymore needed. However this method is calculation time costly.