Time-resolved flow measurements with fast-response aerodynamic probes in turbomachines

A better understanding of unsteady flow phenomena encountered in rotor-stat or interactions is a key to further improvements in turbomachinery. Besides CFD methods yielding 3D flow field predictions, time-resolving measurement techniques are necessary to determine the instantaneous flow quantities of interest. Fast-response aerodynamic probes are a promising alternative to other time-resolving measurement techniques such as hot-wire anemometry or laser anemometry. This contribution gives an overview of the fast-response probe measurement technique, with the emphasis on the total system and its components, the de velopment methods, the operation of such systems and the data processing re quirements. A thorough optimization of all system components (such as senso r selection and packaging, probe tip construction, probe aerodynamics and d ata analysis) is the key of successful development. After description of the technique, examples of applications are given to i llustrate its potential. Some remarks will refer to recent experiences gain ed by the development and application of the ETH FRAP(R) system.