This thesis presents the development of calibration and data-reduction algorithms for non-conventional multi-hole pressure probes. The algorithms that have been developed for conventional 5- and 7-hole probes are not optimal for probes with port arrangements (on the probe tip) that are non-conventional. Conventional algorithms utilize the axisymmetry of the port distribution pattern to define the non-dimensional pressure coefficients. These coefficients are typically defined specifically for these patterns, but fail to correctly represent different patterns of port arrangements, such as patterns without axisymmetry or regularity. The algorithms introduced herein 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 5- and 7-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 first applied to a non-conventional probe, a nearly omni-directional 18-hole probe, and demonstrate very high flow measurement accuracy. Subsequently, the algorithms were applied to a new 12-hole, nearly omni-directional, flow velocity measurement probe capable of measuring reversed flows. The new 12-hole design offers several advantages over a previously developed, 18-hole, nearly omni-directional probe. The probe is optimized in the sense that, regardless of the flow direction, it allows calculation of the 4 unknown flow quantities, i.e. the two flow angles, the velocity magnitude and the static pressure, with the minimum necessary number of holes/ports on the probe tip. This probe also has a non-conventional arrangement of its pressure ports and therefore the new calibration and data-reduction algorithms can be effectively employed. With theoretically generated pressure data for the 12-hole probe, the coefficient definitions are analyzed and found to be well-behaved.

Thesis (M.S. in Mechanical Engineering)--University of Michigan, 2001. / Includes bibliographical references (p. 49). Also available online.

This thesis presents the development of calibration and data-reduction algorithms for non-conventional multi-hole pressure probes. The algorithms that have been developed for conventional 5- and 7-hole probes are not optimal for probes with port arrangements (on the probe tip) that are non-conventional. Conventional algorithms utilize the axisymmetry of the port distribution pattern to define the non-dimensional pressure coefficients. These coefficients are typically defined specifically for these patterns, but fail to correctly represent different patterns of port arrangements, such as patterns without axisymmetry or regularity. The algorithms introduced herein 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 5- and 7-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 first applied to a non-conventional probe, a nearly omni-directional 18-hole probe, and demonstrate very high flow measurement accuracy. Subsequently, the algorithms were applied to a new 12-hole, nearly omni-directional, flow velocity measurement probe capable of measuring reversed flows. The new 12-hole design offers several advantages over a previously developed, 18-hole, nearly omni-directional probe. The probe is optimized in the sense that, regardless of the flow direction, it allows calculation of the 4 unknown flow quantities, i.e. the two flow angles, the velocity magnitude and the static pressure, with the minimum necessary number of holes/ports on the probe tip. This probe also has a non-conventional arrangement of its pressure ports and therefore the new calibration and data-reduction algorithms can be effectively employed. With theoretically generated pressure data for the 12-hole probe, the coefficient definitions are analyzed and found to be well-behaved.

3-hole pressure probes are capable of accurately measuring flow angles in the yaw plane. These probes can be utilized inside a jet engine hot section for diagnostics and flow characterization. Sand and other particulate pose a significant risk to hot section components and measurement devices in gas turbine engines. The objective of this experiment was to develop a better understanding of the sensitivity of experimental 3-hole pressure probe designs to engine realistic sand fouling. In this study, Wedge, Cylindrical, and Trapezoidal probes were exposed to realistic hot section turbine environments of 1050 C at 65-70 m/s. 0-5 micron Arizona Road Dust(ARD) is heated under these conditions and used to foul the yaw probes. The sand deposited on the probe was observed to peel off the probe in thin sheets during ambient cool down. Sand fouling was assessed using a stereoscope and digital camera. Probe calibrations were performed in an ambient temperature, open air, calibration jet to mimic engine cold start conditions at Mach numbers of 0.3 and 0.5. Yaw coefficients were calculated for each probe using probe pressure and jet dynamic pressure readings. These coefficients were used to develop calibration curves for each probe initially, and again for every fouling test. Each probe performed differently, but the trends showed that the sand fouling had little impact on the probe error at Mach 0.3, and a slightly increased effect on the probe error at Mach 0.5. The experiment showed that when flow direction was determined using a true dynamic pressure reading from the jet, the probes were able to accurately measure flow direction even after being significantly sanded, some probes holes being over 50% blocked by sand accumulation. Accelerated erosion testing showed that the trapezoidal yaw probe was by far the most sensitive to sand accumulation, followed by the cylindrical probes, and the least sensitive was the wedge probe. A yaw angle range of interest was chosen to ±10 deg of yaw. The least errors from the Yaw Coefficient, as defined in this report, were found to be in the Trapezoidal and Perpendicular probe configurations. The least error found in the wedge probe. / MS / 3-hole pressure probes are used to measure the speed and direction of air and other fluid flows. These probes can be used inside an active jet engine to measure aspects of the airflow inside the engine during flight. One risk to aircraft engines is sand being ingested into the engine. This can cause significant damage to the engine as well as the hardware inside the engine. The objective of this experiment will be to determine how sand accumulation affects the performance of these probes. The experiment involved sanding the probes in a hot jet, then placing them in front of a room temperature air jet to take measurements. A microscope was used to determine how much sand was on the holes of the probe. Sand was observed to peel off naturally, as the probe cooled from the hot jet. Sand was also noticed to break off during the room temperature jet. The experiment showed that when the Jet pressures was measured from inside the jet, the probes were able to accurately measure flow direction even after being significantly sanded, <50% of the holes being blocked by sand. Of all the probes tested, the Wedge probe performed the best, though a close second was the Trapezoidal probe.