Optimal calibration of directional velocity probes

Abstract

The calibration of directional velocity probes can require significant facility time and resources, especially if carried out in situ. The techniques of the design of experiments are therefore applied in order to formally optimize the selection of calibration points.Amodel is proposed for a generalized directional velocity probe, and this model is used to generate an approximate, polynomial response surface model that is shown to agree well with measurements from both multisensor hot-wire probes and multihole pressure probes, in a variety of geometries. The process of D optimality is then applied based on this response surface model, and a typical probe is calibrated accordingly. The probe is then used to scan the wake of a vortex generator in order to test the efficacy of the reduced calibrations. D-optimal calibration points are shown to offer a significant improvement in data fidelity over conventional rectangular grids, and minimal additional uncertainty is incurred after a 25-fold reduction in the number of calibration points.