Novel, Miniature Multi-Hole Probes and High-Accuracy Calibration Algorithms for their use in Compressible Flowfields

Two new calibration algorithms were developed for the calibration of non-nulling multi-hole probes in compressible, subsonic flowfields. The reduction algorithms are robust and able to reduce data from any multi-hole probe inserted into any subsonic flowfield to generate very accurate predictions of the velocity vector, flow direction, total pressure and static pressure. One of the algorithms PROBENET is based on the theory of neural networks, while the other is of a more conventional nature (polynomial approximation technique) and introduces a novel idea of local least-squares fits. Both algorithms have been developed to complete, user-friendly software packages. New technology was developed for the fabrication of miniature multi-hole probes, with probe tip diameters all the way down to 0.035". Several miniature 5- and 7-hole probes, with different probe tip geometries (hemispherical, conical, faceted) and different overall shapes (straight, cobra, elbow probes) were fabricated, calibrated and tested. Emphasis was placed on the development of four stainless-steel conical 7-hole probes, 1/16" in diameter calibrated at NASA Langley for the entire subsonic regime. The developed calibration algorithms were extensively tested with these probes demonstrating excellent prediction capabilities. The probes were used in the "trap wing" wind tunnel tests in the 14'x22' wind tunnel at NASA Langley, providing valuable information on the flowfield over the wing. This report is organized in the following fashion. It consists of a "Technical Achievements" section that summarizes the major achievements, followed by an assembly of journal articles that were produced from this project and ends with two manuals for the two probe calibration algorithms developed

High-efficiency jet ejector and propulsive jet

According to one embodiment of the invention, a system for altering fluid flow includes a main body having a first fluid flowing therethrough, a plurality of conduits disposed within the main body to form a plurality of flow paths, and a nozzle directing a second fluid through the innermost conduit. The second fluid has a greater velocity than the first fluid. The second fluid successively entrains the first fluid flowing through the flow paths in such a manner that the portion of the first fluid flowing through the innermost flow path existing between the innermost conduit and its adjacent conduit is entrained first and the portion of the first fluid flowing through the outermost flow path existing between the outermost conduit and the main body is last.U

High-efficiency jet ejector and propulsive jet

According to one embodiment of the invention, a system for altering fluid flow includes a main body having a first fluid flowing therethrough, a plurality of conduits disposed within the main body to form a plurality of flow paths, and a nozzle directing a second fluid through the innermost conduit. The second fluid has a greater velocity than the first fluid. The second fluid successively entrains the first fluid flowing through the flow paths in such a manner that the portion of the first fluid flowing through the innermost flow path existing between the innermost conduit and its adjacent conduit is entrained first and the portion of the first fluid flowing through the outermost flow path existing between the outermost conduit and the main body is last.U

High-efficiency jet ejector and propulsive jet

According to one embodiment of the invention, a system for altering fluid flow includes a main body having a first fluid flowing therethrough, a plurality of conduits disposed within the main body to form a plurality of flow paths, and a nozzle directing a second fluid through the innermost conduit. The second fluid has a greater velocity than the first fluid. The second fluid successively entrains the first fluid flowing through the flow paths in such a manner that the portion of the first fluid flowing through the innermost flow path existing between the innermost conduit and its adjacent conduit is entrained first and the portion of the first fluid flowing through the outermost flow path existing between the outermost conduit and the main body is last.U

High-efficiency jet ejector and propulsive jet

According to one embodiment of the invention, a system for altering fluid flow includes a main body having a first fluid flowing therethrough, a plurality of conduits disposed within the main body to form a plurality of flow paths, and a nozzle directing a second fluid through the innermost conduit. The second fluid has a greater velocity than the first fluid. The second fluid successively entrains the first fluid flowing through the flow paths in such a manner that the portion of the first fluid flowing through the innermost flow path existing between the innermost conduit and its adjacent conduit is entrained first and the portion of the first fluid flowing through the outermost flow path existing between the outermost conduit and the main body is last.U

Multi-directional, three component velocity measurement pressure probe

The development of a nearly-omni-directional pressure probe for three-velocity-component and pressure measurements is described, with particular focus on the techniques and technology employed in probe construction, calibration, electronic interfacing and frequency-response study. The device eliminates the velocity directionality limitations of current multi-hole probes and makes a valuable, rugged tool for use in complex 3-D flow mapping and aerodynamic design and evaluation, in basic research as well as industrial development settings. The probe performance is demonstrated in a flowfield with flow reversal downstream of a backward-facing step. The probe provides low-frequency response capabilities. The probe's main element is a multi-pressure port spherical head, which may include eighteen ports. Fiber optic interferometry techniques may be incorporated to significantly increase frequency response.U