Measuring and testing – Fluid flow direction – With velocity determination
Patent
1993-02-05
1995-07-25
Chilcot, Jr., Richard E.
Measuring and testing
Fluid flow direction
With velocity determination
73862045, 73862043, G01W 100, G01F 174
Patent
active
054351782
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND TO THE INVENTION
I. Field of the Invention
This invention relates to blast gauges and particularly to a non-directional gauge for blast measurements.
II. Description of Known Art
Measurement of blast involves the insertion of an instrumented body into the flow field. Gauges of this type are known which feature a conventional pressure transducer housed within a streamlined fairing. The fairing is designed to cause minimal perturbation of the blast field being measured. Such known gauges only function accurately when aligned in such a way that the incident blast wave traverses the face of the transducer at grazing incidence. Such alignment requires advance knowledge of the direction of travel of the blast wave.
When measurements of blast waves are made in enclosed surroundings, such as rooms, both direct and reflected waves are produced which travel in different directions. A gauge may be set to measure one of the waves, but it will be misaligned with respect to most of the other waves that arise. The measurement of the reflected waves is most important as they may interact and comprise a stronger force than the initial wave. If a reflected wave should arrive at right angles to the face of the transducer in such a gauge, the perceived pressure could be more than double the true static value. It is clear that such directional blast gauges are of little value when blast measurements need to be made in enclosed surroundings.
SUMMARY OF THE INVENTION
The present invention provides a non-directional blast gauge which will record the amplitude of a blast wave regardless of its orientation. The gauge is also capable of providing directional information for each wave reaching it.
According to the present invention there is provided a blast gauge comprising a spherical fairing containing four pressure sensors whose positions on the surface of the sphere form the apices of a tetrahedron.
The spherical fairing may be hollow or comprise a solid block with recesses to accept the sensors. The fairing may be constructed from wood, metal or a synthetic polymer or composite based on such a polymer such as resin bonded glass fiber. The fairing may comprise a metal or synthetic polymer shell containing a foam filling. In a preferred form the fairing is fabricated from aluminum or an alloy thereof. The size of the spherical fairing should be small to avoid disrupting the blast wave pattern. However the minimum size of the fairing is also limited by the particular timing method being used and the consequent need to allow a reasonable time delay between the shock waves impinging on the transducers contained in it. Accuracy is reduced if the fairing is too small. In practice the minimum size is determined by the size of the sensors which are contained within it. The signals from the sensors are carried by conductors through cavities in the interior of the fairing into a tubular support or sting. The support must have sufficient rigidity to withstand any incident blast; however its diameter must also be as low as possible so as not to perturb the blast waves passing it.
The pressure sensors may be standard sensors which are commercially available or formed using piezo-sensitive film. "Endevco" sensors and those supplied by Entran Devices, both from the United States of America, are particularly effective. However other types may be used.
The signals from the pressure sensors are fed to signal processing means where the amplitude of the incident pressure on each sensor and its time of occurrence are stored. The stored information may be used to provide details of the amplitude and direction of successive blast waves which fall on the gauge following an initial event.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention be clearly understood it will now be described with reference to the accompanying drawings in which:
FIGS. 1A, 1B and 1C show a plan and two side views of a blast gauge according to the invention.
FIG. 2 is a cross-sectional view of the gauge shown in FIG. 1.
FIG. 3 is a schematic view of a
REFERENCES:
patent: 2855779 (1958-10-01), Zard
patent: 3318146 (1967-05-01), De Leo et al.
patent: 3603951 (1971-09-01), Bracken
patent: 3695103 (1972-10-01), Olson
patent: 3930412 (1976-01-01), Mallon et al.
patent: 4207621 (1980-06-01), Clearwaters et al.
patent: 4232547 (1980-11-01), Kasper
patent: 4498348 (1985-02-01), Wesson
patent: 4635479 (1987-01-01), Salisbury, Jr. et al.
patent: 4659034 (1987-04-01), Diekmann
patent: 5170670 (1992-12-01), Fasching et al.
Chilcot Jr. Richard E.
G. D. Engineering Associates Limited
Oen William
Rudy Christopher John
LandOfFree
Blast gauge wherein four pressure sensors are positioned in a te does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Blast gauge wherein four pressure sensors are positioned in a te, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Blast gauge wherein four pressure sensors are positioned in a te will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-733004