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A sensor for measuring flow direction and airspeed that is suitable, because of its small size, for rapid instrumentation of research airplanes is described. A propeller driven sphere rotating at a speed proportional to airspeed presents a reflective target to an electro-optical system such that the duty cycle of the resulting electrical output is proportional to yaw angle and the frequency is proportional to airspeed.
Recently, there has been significant interest in using bismuth metal as a propellant in Hall Thrusters [1, 2]. Bismuth offers some considerable cost, weight, and space savings over the traditional propellant--xenon. Quantifying the performance of liquid metal-fed Hall thrusters requires a very precise measure of the low propellant flow rates [1, 2]. The low flow rates (~10 mg/sec) and the temperature at which free flowing liquid bismuth exists (above 300 C) preclude the use of off-the-shelf flow sensing equipment [3]. Therefore a new type of sensor is required. The hotspot bismuth flow sensor, described in Refs. [1-5] is designed to perform a flow rate measurement by measuring the velocity at which a thermal feature moves through a flow chamber. The mass flow rate can be determined from the time of flight of the thermal peak, [4, 5]. Previous research and testing has been concerned mainly with the generation of the thermal peak and it's subsequent detection. In this paper, we present design improvements to the sensor concept; and the results of testing conducted to verify the functionality of these improvements. A ceramic material is required for the sensor body (see Fig. 1), which must allow for active heating of the bismuth flow channel to keep the propellant in a liquid state. The material must be compatible with bismuth and must be bonded to conductive elements to allow for conduction of current into the liquid metal and measurement of the temperature in the flow. The new sensor requires fabrication techniques that will allow for a very small diameter flow chamber, which is required to produce useful measurements. Testing of various materials has revealed several that are potentially compatible with liquid bismuth. Of primary concern in the fabrication and testing of a robust, working prototype, is the compatibility of the selected materials with one another. Specifically, the thermal expansion rates of the materials relative to the ceramic body cannot expand so much as to cause cracks in the body or cause the bond between parts to delaminate. Those parts that will carry the current pulse must be electrically conductive while the sensor body must be an electrical insulator. Generally, the material choices as well as the sensor design must aid to preserve the integrity of the thermal feature to obtain accurate measurements. The present aim is to also incorporate, into the sensor body, an active heating arrangement based on ceramic heater technology similar to that used in semiconductor manufacturing.
Electronic sensor accurately measures and controls flow of plasma, whole blood, or drugs in solution. Since sensor does not directly contact fluid, it does not have to be sterilized. It is compatible with disposable bottles, tubes, and hypodermic needles widely used in hospitals. Only modification necessary is in tube, which must contain two small metal inserts, spaced to fit in curved thermistor plates.
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Miniature sensors are needed for rapid and uncomplicated installation on light aircraft engaged in stability research programs. One particularly difficult sensor to miniaturize to the required degree has been a flow angle and velocity sensor for measuring the local flow ahead of a wing. However, by using an electrooptical technique it was possible to overcome the encountered difficulties and to design a sensor satisfying the requirements. The developed sensor for measuring angle-of-attack, yaw, and airspeed was shown to be suitable for rapid instrumentation of research aircraft because of its small size. The size reduction was accomplished by a design feature which eliminates the need for slip rings and wiring within the movable components of the sensor.
Simple, rugged, lightweight transducers detect periodic vortices. Fiber-optic-coupled transducers developed to measure flows over wide dynamic ranges and over wide temperature ranges in severe environments. Used to measure flows of fuel in advanced aircraft engines. Feasibility of sensors demonstrated in tests of prototype sensor in water flowing at various temperatures and speeds. Particularly attractive for aircraft applications because optical fibers compact and make possible transmission of sensor signals at high rates with immunity from electromagnetic interference at suboptical frequencies. Sensors utilize optical-to-optical conversion via photoelastic effect.
A theoretical analysis of standing waves in a pipe with flow was conducted aimed toward the development of a flowmeter based on a measurement of phase difference between two points on the circumference of a pipe separated axially by an integral multiple of half sound wavelength. Effects of nonzero Mach number, variable ratios of upstream and downstream running waves, choice of location of the sensing pressure taps, and the incorrect spacings were examined numerically. Calculations were also made for steam flow where the maximum Mach number is much smaller than in cold air flows. For an industrial application where steam flow velocities are below 50 m/s, a very accurate sensor is shown to be possible. Experimental data were obtained by using an active aeroacoustic source over the range of 50 m/s to zero in an air flow. Experimental phase plots obtained from several coast-down tests have been compared with analytical results. The agreement with theory is excellent when the spacings are near N(lambda)/2 and the sensing locations are near the pressure antinodes. Otherwise, some zero shifts are introduced. Theory predicts that for steam flow much better results can be expected because the maximum Mach number is much smaller. Effects due to the (1-M-squared) factor would be imperceptible for steam flow.
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We are investigating a microwave resonant cavity transducer for flow sensing in the vessel of a high temperature fluid advanced reactor (AR), such as a molten salt cooled reactor (MSCR) or a sodium fast reactor (SFR). This transducer is a hollow metallic cylindrical cavity, with the flat wall of the cylinder flexible enough to undergo microscopic deflection due to dynamic fluid pressure. Membrane deflection leads to a shift in the resonant frequency, which can be detected with a spectrum analyzer. We have performed a proof-of-concept experiment of flow sensing with the transducer in liquid sodium at 340°C in impinging liquid jet geometry. The transducer remained in liquid sodium for 70 days. After removal, no structural damage was observed, and the expected transducer response was verified in a water test. Because long-term (multi-year) experimental tests of transducer resilience to harsh environment are not practical, we have developed a probabilistic model of creep to estimate transducer resilience to the harsh environment. The probabilistic model considers diffusion creep under the condition of high temperature and low stress, where the stress and temperature are allowed to be random variables with Gaussian distributions. Using the probabilistic model, we estimate inelastic membrane deflections due to creep for several temperature ranges. We conclude that for temperatures less than 650°C, creep has negligible long-term effect on the transducer performance. Since a yellowish residue was observed on the transducer surface after 70 days of immersion in liquid sodium, we have investigated possible evidence of corrosion. Chromium depletion is a typical indicator of the corrosion process in stainless steel. Scraping off a residue from the transducer and performing scanning electron microscopy (SEM) with energy dispersive analysis (EDS) did not find any chromium in the residue. Approximately 60% of the residue consisted of copper, which can be attributed to contamination of sodium due to powder residue from machining of copper and brass components of the transducer.
A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.
Devices that include a liquid chamber including at least two ports, wherein the opening of a first port is larger than the opening of a second port, an air chamber including at least one port, and a membrane located between the liquid chamber and the air chamber, and a pressure sensor coupled to the port in the air chamber are provided. Systems including the disclosed devices are also provided. The systems include liquid in the liquid chamber of the device. Methods of using the devices and systems include measuring one or more properties of a liquid by flowing the liquid through the liquid chamber of the system and measuring the pressure produced due to the difference in size of the ports in the liquid chamber.
This report will review updates on the status of F-STAr. First, the report will describe a general overview of the test article and how each component interacts. Then, each main component will be discussed in a deep dive section which will review the design and other relevant details. F-STAr components which are discussed in more detail include the 120 GPM-pump, the support structure and test sections, 5 kW-heater, the 2 kW-cooler and cooling system, and the submersible flowmeter. Finally, this report will conclude with a brief recap and a bulleted outline of the path moving forward.
Readily-available fuel meters can be used to aid in fuel oil conservation in homes and commercial buildings. Device also includes failure monitor that activates warning light and horn if meter fails.
Very-thin-film dielectric coating stable over range of temperatures developed. This dielectric coating, combination of fused silica and thermoplastic polymer, has sufficient stability to withstand stresses placed upon it by cycling to and from cryogenic temperatures. Coating tailored to meet almost any criterion of roughness height. Useful for research in application of hot-film sensors to airfoils.
X-15 aircraft spherical, hypersonic flow direction sensor - operational and performance characteristics, and flight data
Flow angle sensor and remote readout system for use with cryogenic fluids