Calibration and Data-Reduction Algorithms for Nonconventional Multihole Pressure Probes

Abstract

The development of calibration and data-reduction algorithms for nonconventional multihole pressure probes is presented. The algorithms that have been developed in the past for conventional five- and seven-hole probes are not optimal for probes with port arrangements (on the probe tip) that are nonconventional. Conventional algorithms utilize the axisymmetry of the port distribution pattern to define the nondimensional pressure coefficients. These coefficients are typically defined specifically for these patterns, but fail to represent correctly different patterns of port arrangements, such as patterns without axisymmetry or regularity. The algorithms introduced can handle any pattern of port arrangement, from axisymmetric and regular to random. Moreover, they eliminate the need to separate the measurement domain of a probe to low-angle and high-angle regimes, typical in conventional five-and seven-hole-probe algorithms that require two different sets of pressure coefficient definitions and procedures. Additionally, the algorithms have been formulated such that they facilitate redundancy implementations, especially in applications where such redundancy is important, such as air-data systems. The developed algorithms are applied to a nonconventional probe, a nearly omnidirectional 18-hole probe, and demonstrate very high flow-measurement accuracy