The second part of this paper deals with the analysis of the 2D LDA measurements carried out within the high-speed multistage axial compressor CREATE. First the interactions correlations are quantified using the deterministic stresses introduced by Adamczyk. Secondly, a modal decomposition shows that the interactions are characterized by the presence of spatial harmonics (spinning lobes) given by a linear combination of the blades numbers. An original measurement of the rotating speed of the spinning lobes has been carried out allowing to identify almost all the spinning lobes in the first inter row region resulting from the R1-S1 interactions. For the first stage, where the influence of the downstream rows is low, the measured flow field is well reproduced by the model of Tyler and Sofrin. Spatial DFT of the flow field calculated for each time of the compressor time period show that there is a pulsation of the spatial harmonics with the period associated to the minimum elapsed time to recover the same relative positions of the rotor and stator rows.

The design of modern aircraft engines increasingly involves highly sophisticated methodologies to match the current development pace. International company relations affect the collaboration between design offices all around the world. An important part of academic mission of modern engineering education is to produce graduates with skills compatible with industrial needs. Education may readjust accordingly to meet the higher requirements. However, a realistic scenario of the design process of an aircraft engine cannot possibly be transferred one-to-one into the student education process. A unique attempt to overcome this discrepancy was the International Gas Turbine Project. Within this project, undergraduate students have designed the cooling system of the HPT blades for a 30,000 lb thrust two-spool turbofan aeroengine. This project was collaboration between the Jet Propulsion Laboratory of TU Berlin, the Turbomachinery Group of EC Lyon and the Turbomachinery Laboratory of ETH Zurich. It also involved mentoring industry professionals from Rolls-Royce Deutschland, MTU, SNECMA and Alstom Power. Similar to modern aeroengine company structures, the design tasks included multi-component, multi-disciplinary and international interfaces of different educational systems. The student teams considered various aerothermodynamic and mechanical integrity aspects of the design. Particular attention was paid to design of the compressor, the secondary air system and the HP turbine including blade cooling. The three Universities integrated the project differently into their education curriculum and approached the tasks with different levels of software involvement. In this paper, the technical details of the design process, and the different approaches adopted are presented. Besides the application of turbomachinery-related knowledge, the impact of student interactions on the technical aspects of the project is discussed. The interfaces, including information management and the involvement of industrial partners are also addressed. Team spirit developed between the students from an initial competitive behavior to a final feeling of sitting in the same boat. It was observed that increased effort was required from academic staff in comparison to the conventional academic instruction. Nevertheless, students greatly benefited from the social interaction and an early training-on-the-job tuned to current industrial needs.

This paper relates to laser anemometry measurements (LDA) conducted in a high speed, three-stage, axial compressor. Particular attention has been paid to the estimation of the measurement accuracy. Three different synchronization procedures have been implemented in order to enhance the exactness of the location in the rotating frame for each situation. Small flat windows mainly provide the optical accesses. But, large curved glasses could also be used, the optical distortions resulting from the surface curvature being corrected with the help of an optical assembly developed for the L2F technique and extended to the LDA technique. Furthermore, in order to avoid interpolation processes when changing the frame of reference, the spatial and time discretizations have been defined in accordance with the numbers of rotor and stator blades. The presented measurements have been performed, at 50% blade height, in the first three inter row sections, the azimuthal exploration covering machine periodicity.

This paper deals with the experimental quantification of the unsteady effects of the interactions between rotor and stator rows in high speed compressors. Due to the fact that the levels of the periodic fluctuations arising from the unsteady interaction may be low compared with the random fluctuations arising from the measurement uncertainties, it is crucial to minimize the errors inherent to the used technique. The first part of the paper concentrates on technical details relative to the experimental process. The second part is devoted to the data postprocessing. Two tools for analysing the rotor-stator interactions are presented. The first tool is based on a decomposition of the flow field which was initially introduced to solve numerical problems when attempting to calculate the flow field in a multi-row configuration. The second tool is based on a spectral analysis of the signal, that qualifies the interaction in a sense of circumferential spinning lobes. Experimental results obtained within both an axial and a centrifugal high speed compressors are used to illustrate the data processing. In both cases, the effects of the unsteady interaction are quantified.

In turbomachinery applications, optical access needed for laser anemometry (L2F) measurements must be provided by curved glass windows to avoid introducing disturbances into the flow. However, the curvatures lead to optical distortions of the laser beams which prevent the creation of acceptable foci. These distortions can be eliminated by inserting a simple and inexpensive corrective window between the frontal lens of the anemometer assembly and the shroud window. First, a simplified analytical method is presented to determine the geometric characteristics and the position of this corrective window. Then, a more sophisticated numerical method is described and applied to the case of an axial transonic compressor currently under investigation.