Analysis of Rotor-Stator-Interaction and Blade-to-Blade Measurements in a Two Stage Axial Flow Compressor

Abstract

In order to improve unsteady CFD analysis for turbomachinery applications, there is still the need for high quality experimental data for validation. The first aim of this paper is to represent a unique work in providing unsteady data for the purpose of a CFD test case. Second, a detailed analysis of rotor-stator-interaction in a multistage compressor is performed by means of accompanying frequency analysis of the blading and the tip leakage flow for different indexing positions. The transonic two stage axial flow compressor is equipped with integrally bladed rotors and vanes with hub and tip shrouds with regard to a modern high pressure jet engine compressor. For detailed flow measurements both intrusive and nonintrusive measurement techniques were used. Beside pressure probes mounted with a semiconductor and microstrain gauges applied to the blades and vanes, a three component Doppler laser-two-focus velocimeter was used. The results of the time resolved pressure traverse measurements in the axial gaps as well as the analysis of the tip leakage flow show the propagation of the wakes and the potential upstream influence, which can be clearly detected by the blade passing frequencies as well. Additionally, the results of the blade-to-blade measurements impart an idea of the intrarotor-transport of the fluid and the flow phenomena within the rotor. Beside the detailed flow analysis, the preferential aim of this paper is to establish a method for the detection of flow phenomena due to the blade-row-interaction by means of a frequency analysis. This paper shows that a correlation of the fast Fourier transform results of strain gauges and semiconductor probes in the axial gaps and tip leakage flow region is a very promising starting point, especially for the analysis of forced response operating points.