Refinements of a L2F anemometry technique for inter-blade flow field investigations in high-speed turbomachinery

The need for detailed experimental measurements in small, high rotational speed compressors leads us to refine the L2F measurement technique, in particular the data acquisition procedures for the case of investigations within the rotating blade passages. The extent of shadow regions (due to blade twist) is predicted prior to making any measurement using a modelling software which is outlined in this paper. Such prediction allows us to assess the feasibility of creating the probe volume and collecting the scattered light, and can help choose the orientation of the lines of sight and the window locations. Due to reflections from the blade surfaces, there are usually regions where measurement is impossible. The analysis of these zero data zones is presented and leads to an optimized blade pitch partition for decreasing the acquisition time and better defining the azimuthal location of the acquired data. Two examples of the benefits which can be obtained using such a procedure are presented.