Analysis of Unsteady Vortical Flow Field in Rotating Cascade Using Instantaneous Pressure Field Measurement and Smart Visualization of CFD

Abstract

The combination of experimental and numerical analyses is essential to the elucidation of unsteady flow phenomena in turbomachinery. From this point of view, an instantaneous pressure field measurement technique and a smart visualization technique for CFD results are described in the present article. In the instantaneous pressure field measurement technique where 30 high response pressure transducers and a spatial-temporal interpolation of the pressure transducer signals are utilized, time-series data of the instantaneous pressure distribution on the casing wall of one pitch blade passage are obtained to capture transient phenomena in unsteady flow fields of rotating cascades. In the smart visualization technique for CFD results, the identification of vortex cores and topology analysis of limiting streamlines, which are based on the critical-point theory, are performed to extract fluid dynamic knowledge from CFD results. An application example of the instantaneous pressure field measurement technique and the smart visualization technique is presented, in which those are applied to the elucidation of the spike-type stall inception in an axial flow compressor rotor.