Abstract: An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

Abstract: A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

Abstract: A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

Abstract: An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

Abstract: A device and method are provided for determining the thickness of a layer of solid ice, a mixture of ice and water, or a mixture of ice and other liquid, accumulated on the outer surface of an object. First and second total impedance sensors are operated at first and second frequencies. Corresponding first and second AC total impedance measuring circuits are coupled to the first and second sensors to produce output voltages based on the total impedance changes sensed by the sensors. A processor is coupled to the first and second measuring circuits to generate an output value using the measured output voltages. The output value is indicative of the thickness of the ice or ice and water mixture, or ice and other liquid.

Abstract: A system and method are provided for recording density changes in a flow field surrounding a moving object. A mask having an aperture for regulating the passage of images therethrough is placed in front of an image recording medium. An optical system is placed in front of the mask. A transition having a light field-of-view and a dark field-of-view is located beyond the test object. The optical system focuses an image of the transition at the mask such that the aperture causes a band of light to be defined on the image recording medium. The optical system further focuses an image of the object through the aperture of the mask so that the image of the object appears on the image recording medium. Relative motion is minimized between the mask and the transition. Relative motion is also minimized between the image recording medium and the image of the object.

Abstract: A housing block is provided having an upper surface conforming to the test surface of a model or aircraft. An oil film is supplied upstream of a transparent wedge window located in this upper surface by an oil pump system located external to the housing block. A light source located within the housing block supplies a light beam which passes through this transparent window and is reflected back through the transparent window by the upper surface of the oil film to a photo-sensitive position sensor located within the housing. This position sensor allows the slope history of the oil film caused by an aerodynamic flow to be determined. The skin friction is determined from this slope history. Internally located mirrors augment and sensitize the reflected beam as necessary before reaching the position sensor. In addition, a filter may be provided before this sensor to filter the beam.

Abstract: A velocimeter measures flow characteristics of a flow travelling through a chamber in a given direction. Tracer particles are entrained in the flow and a source of radiant energy produces an output stream directed transverse the chamber and having a sufficient intensity to vaporize the particles as they pass through the output stream. Each of the vaporized particles exploding to produce a shock wave and a hot core, and a flow visualization system tracks the motion of the hot cores and shock waves to thereby measure velocity of each tracer particle, and temperature of the flow around the tracer.

Abstract: A process for reducing skin friction, inhibiting the effects of liquid turbulence, and decreasing heat transfer in a system involving flow of a liquid along a surface of a body includes applying a substantially integral sheet of a gas, e.g., air, immediately adjacent to the surface of the body, e.g., a marine vehicle, which has a longitudinally grooved surface in proximity with the liquid and with a surface material having high contact angle between the liquid and said wall to reduce interaction of the liquid, e.g., water, with the surface of the body, e.g., the hull of the marine vehicle.

Abstract: An automatic transducer selection system for fluid pressure measurement functions by using two or more transducers with different ranges of accuracy and also by incorporating comparator circuitry which automatically selects the transducer reading nearer to full scale. An electronic signal or output from the comparator is preferably nested such that a continuous voltage is generated in accordance with the fluid pressure being measured, thus making the system appear to function as a single transducer with a wide range of accuracy.

Abstract: A method and apparatus to measure the thickness of liquid 12 on a surface 14 independent of liquid conductivity. Two pairs of round, corrosion resistant wires, 18 and 20, are mounted in an insulating material 16 such that the cross-sectional area of each wire is flush with and normal to the surface 14. The resistance between each pair of wires 18 and 20 is measured using two AC resistance measuring circuits 22 and 24 wherein the ratio of the outputs of the two resistance measuring circuits is indicative of the thickness of the liquid 12 on the surface 14.

Abstract: An ice detector 11 is provided for the determination of the thickness of ice 22 on the outer surface 12 on an object (e.g., aircraft 10) independently of temperature or the composition of the ice 22. First capacitive gauge 16, second capacitive gauge 18, and temperature gauge 20 are embedded in embedding material 14 located within a hollowed out portion of outer surface 12. This embedding material 14 is flushed with outer surface 12 to prevent undesirable drag. First capacitive gauge 16, second capacitive gauge 18, and temperature gauge 20 are respectively connected to first capacitance measuring circuit 24, second capacitance measuring circuit 26, and temperature measuring circuit 28. The geometry of first and second capacitive gauges 16 and 18 is such that the ratio of the voltage outputs of first and second capacitance measuring circuits 24 and 26 is proportional to the thickness of ice 22, regardless of ice temperature or composition. This ratio is determined by offset and dividing circuit 29.

Abstract: The invention relates to a smoke generator capable of emitting a very thin, laminar stream of smoke for use in high detail flow visualization. The generator is also capable of emitting a larger but less stable "rope" of smoke. The invention consists of a pressure supply 29, and fluid supply 28, which supply smoke generating fluid 25 to feed tube 22. Feed tube 22 is directly heated by electrical resistance from current supplied by power supply 30 and regulated by constant temperature controller 32. Smoke exit hole 21 is drilled in the wall of feed tube 22. Because feed tube 22 is heated both before and past exit hole 21, no condensation of smoke generating fluid occurs at the smoke exit hole, enabling the production of a very stable smoke filament 16. The generator is small in size, thereby avoiding wind turbulence in front of the test model 11.

Abstract: A method and apparatus for improving the quality of photographic images by projection through a linear radial transmission filter. The invention yields small detail blending or contrast enhancement of small details with a minimum loss of sharpness. A simple enlarger and a linear radial transmission filter are used to process a wide variety of images and are capable of simple adjustment to vary the resulting degree of blending or enhancement.

Abstract: An automatic transducer selection system for fluid pressure measurement functions by using two or more transducers wtih different .Iadd.measurement .Iaddend.ranges .[.of accuracy.]. and also by incorporating comparator circuitry which automatically selects the transducer reading nearer to full scale. An electronic signal or output from the comparator is preferably nested such that a continuous voltage is generated in accordance with the fluid pressure being measured, this making the system appear to function as a single transducer with a wide .Iadd.measurement .Iaddend.range of .Iadd.high .Iaddend.accuracy.