One-Dimensional Flow-Adaptive Measurement Grid Algorithm for Pneumatic Probe Measurements

Abstract

The subject of this paper is an algorithm for a flow-adaptive measurement grid developed for pneumatic probe measurements in steady flow fields. The performance of the algorithm is demonstrated by a circumferential traverse at a constant radial position with a pneumatic five-hole probe in an annular cascade wind tunnel. Compared to a conventional equidistant measurement grid, the algorithm automatically computes the amount of measurement points needed for a high resolution of the pressure distribution in turbomachinery flows. The algorithm is fully automated and approximates the pressure distribution of a preliminary transient measurement very accurately. Even though the spacing of the computed measurement points differs significantly from an equidistant grid, postprocessing corrections related to the probe head geometry can still be applied. Accompanying a redistribution of the measurement points is a reduction in the overall points needed for the measurement. The commonly encountered problem of data oversampling is therefore avoided. Compared to a conventional equidistant measurement grid, the adaptive grid showed a significant reduction in the overall measurement points and a reduction in the duration of the measurement—while maintaining the accuracy in the computation of flow parameters. The purpose of this paper is to demonstrate the performance of an automatic detection of measurement points so that valuable measurement time can be saved without a loss in quality of the obtained data.