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OwnerJames C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, George C. Mateer +1inventors
InventorsJames C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, George C. Mateer, Aviel Brosh
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An arrangement for sensing the fluid separation along a surface employs a thermally insulating element having a continuous surface blending into and forming a part of the fluid flow surface. A heating conductor is mounted on the element at the element surface. Two thermal sensors each has a conductor, the sensor conductors being mounted at the element surface on opposite sides of the heating conductor. In operation a fluid flow along the surface in a direction successively through the conductors carries heat in its wake to the downstream conductor where it is sensed. The upstream sensor also senses the temperature of the fluid flow before it reaches the heating conductor. When the fluid flow separates from the surface at the area of the heating and sensing conductors, a sudden decrease in the temperature of the downstream sensor conductor and concomitant increase in the temperature of the upstream sensor conductor is an indication of the separation. When the temperatures are returned to the state achieved during normal flow, the indicator thereby indicates the normal, attached fluid flow. The conductors may be, for example, wires or thin films, and should be within the viscous sub-layer of the expected fluid flow. The use of an upstream sensor conductor with the downstream sensor conductor is desirable as tending to compensate for changes in the free or ambient temperature of the fluid in the flow. A single heater and several pairs of sensors and corresponding sensor conductors may be used to detect not only the fluid flow and the separation, but the direction of the fluid flow, over the fluid flow surface.
A flow separation detector or the like comprising a body with a low thermal conductivity, said body having a surface adapted to be aligned with and become part of the surface from which the flow separation is to be detected, a heater conductor having a longitudinal axis, two temperature sensing conductors each having a longitudinal axis, said conductors being mounted substantially flush with said body surface so as to minimize flow interference, said temperature sensing conductors being mounted on opposite sides of said heater conductor in the direction of the flow to be detected, means for heating said heater conductor, means for measuring the temperature differential between said temperature sensing conductors, said differential being a function of the flow separation.
For sensing a fluid flow separation along a surface, the combination comprising a thermally insulating element having a continuous surface for blending into and forming a part of the said fluid flow surface, a heating wire, means for applying a heating current to said wire, two thermal sensors each having a separate respective conductor the temperature of which is sensed by its respective sensor, all of said conductors being mounted on said element at said element surface and having axes parallel to each other and perpendicular to the direction of fluid flow, the said thermal sensor conductors being on opposite sides, in the sense of said flow direction, of said heating wire.
For sensing a fluid flow separation along a surface, the combination comprising a thermally insulating element having a continuous surface for blending into and forming a part of said fluid flow surface, a conductor to be heated, means for applying a heating current to said conductor, a plurality of pairs of thermal sensors, each having a separate respective conductor the temperature of which is sensed by its respective sensor, all of said conductors being at said element surface, the conductors of each pair being equidistant and on opposite sides of said conductor to be heated.
Dependencies are inferred from the claim text.