MEASUREMENTS OF THE 3D FLOW FIELD DOWNSTREAM OF AN AIRCRAFT ENGINE FAN

摘要

Flow field measurements have been performed in a jet engine fan. As a part of a sensitivity study on the influence of geometry changes on the performance of the compressor the experiments provide a data base for the verification of extensive numerical simulations covering the fan blades. These investigations help to improve the understanding of how changes in component geometry due to wear affect the engine. The experimental investigations were carried out downstream of the fan of a jet engine on the test cell at Lufthansa Technik AG The main focus of the measurements was to provide highly resolved flow field data downstream of the OGV. A pneumatic five-hole probe was applied in order to obtain 3D information of the flow properties. In order to detect and to resolve the wakes of the OGVs and of the midspan shrouds of the rotor blades the measurements had to be performed along the blade height and had to cover more than one OGV spacing. Therefore, it was necessary to position the probe at various radial and circumferential locations. The radial positioning of the probe was performed by a standard traversing unit. The different circumferential locations were achieved by a specially developed traversing mechanism on a modified engine fan case, which allowed a continuous positioning in the range of two OGV spacings. The experiments were carried out for two different operating points of the jet engine. For each of these operating points, the engine was operated with nominal and with increased tip clearance above the fan rotor in order to simulate different wear conditions. The paper explains the necessary modifications to the jet engine and the set up for the experiments. Furthermore, measured results are shown and compared to the results derived from the CFD simulations which were performed prior to the experimental investigations.