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At least 1,747 records · Page 97

The Minimum Impulse Thruster

The Minimum Impulse Thruster (MIT) was developed to improve the state-of-the-art minimum impulse capability of hydrazine monopropellant thrusters. Specifically, a new fast response solenoid valve was developed, capable of responding to a much shorter electrical pulse width, thereby reducing the propellant flow time and the minimum impulse bit. The new valve was combined with the Aerojet MR-103, 0.2 lbf (0.9 N) thruster and put through an extensive Delta-qualification test program, resulting in a factor of 5 reduction in the minimum impulse bit, from roughly 1.1 milli-lbf-seconds (5 milliNewton seconds) to - 0.22 milli-lbf-seconds (1 mN-s). To maintain it's extensive heritage, the thruster itself was left unchanged. The Minimum Impulse Thruster provides mission and spacecraft designers new design options for precision pointing and precision translation of spacecraft.

thruster↗

Ignition Characterization Test Results for the LO2/Ethanol Propellant Combination

A series of contracts were issued by the Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) un der the auspices of the Exploration Systems Mission Directorate to de velop and expand the maturity of candidate technologies considered to be important for future space exploration. One such technology was to determine the viability of incorporating non-toxic propellants for R eaction Control Subsystems (RCS). Contract NAS8-01109 was issued to A erojet to develop a dual thrust Reaction Control Engine (RCE) that ut ilized liquid oxygen and ethanol as the propellants. The dual thrust RCE incorporated a primary thrust level of 870 lbf, and a vernier thru st level of 10 - 30 lbf. The preferred RCS approach for the dual thru st RCE was to utilize pressure-fed liquid oxygen (LOX) and ethanol pr opellants; however, previous dual thrust feasibility testing incorporated GOX/Ethanol igniters as opposed to LOX/Ethanol igniters in the de sign. GOX/Ethanol was easier to ignite, but this combination had syst em design implications of providing GOX for the igniters. A LOX/Ethan ol igniter was desired; however, extensive LOX/Ethanol ignition data over the anticipated operating range for the dual thrust RCE did not e xist. Therefore, Aerojet designed and tested a workhorse LOX igniter to determine LOX/Ethanol ignition characteristics as part of a risk m itigation effort for the dual thrust RCE design. The objective of the ignition testing was to demonstrate successful ignition from GOX to LOX, encompassing potential two-phase flow conditions anticipated being present in real mission applications. A workhorse igniter was desig ned to accommodate the full LOX design flowrate, as well as a reduced GOX flowrate. It was reasoned that the initial LOX flow through the igniter would flash to GOX due to the latent heat stored in the hardwa re, causing a reduced oxygen flowrate because of a choked, or sonic, flow condition through the injection elements. As LOX flow continued, the hardware would chill-in, with the injected oxygen flow transitioning from cold GOX through two'phase flow to subcooled LOX. The Workh orse igniter was well instrumented: Pressure and temperature instrumentation permitted oxygen state points to be determined in the igniter oxidizer manifold, and gas-side igniter chamber thermocouples provide d chamber thermal profile characteristics. The cold flow chamber pres sure (Pc) for each test was determined and coupled with the igniter chamber diameter (De) to calculate the characteristic quench parameter (Pc x Dc), which was plotted as a function of core mixture ratio, MRc . Ignition limits were determined over a broad range of valve inlet conditions, and ignition was demonstrated with oxygen inlet conditions that ranged from subcooled 210 deg R LOX to 486 deg R GOX. Once ign ited at cold GOX conditions, combustion was continuous as the hardwar e chilled in and the core mixture ratio transitioned from values near 1.0 to over 12.5. Pulsing is required in typical RCS engines; therefore, the workhorse igniter was pulse tested to verify the ability to pr ovide the required ignition for a pulsing RCE. The minimum electrical pulse width (EPW) of the dual thrust RCE was 0.080 seconds. Igniter pulse tests were performed at three conditions: (1) an EPW of 0.080 se conds at 25% duty cycle for 400 pulses; (2) an EPW of 0.160 seconds a nd a 5% duty cycle for 124 pulses; (3) an EPW of 0.160 seconds and a 50% duty cycle for 380 pulses. Successful ignition of LOX/Ethanol was demonstrated over a broad range of valve inlet conditions, with the empirically determined LOX/Ethanol ignition limits extending the previous database established for GOX/Ethanol ignition limits. Although th e observed chill-in characteristics of the hardware varied significan tly with flowrate, ignition was readily achieved. Combustion was marg inal at extremely fuel-rich conditions, and it fluctuated as the oxygen passed rough the twophase flow regime during the period of hardware chill-in. Pulse testing showed good repeatability with 100 percent r e-ignition for all pulses. Certain pulse-to-pulse repeatability requirements for actual RCS operation may necessitate establishment of mini mum oxygen flow rates and engine thrust levels for satisfactory engin e performance.

Robinson, Philip J.↗

Heat driven pulse pump

A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

Benner, Steve M↗

Ethylene monitoring and control system

A system that can accurately monitor and control low concentrations of ethylene gas includes a test chamber configured to receive sample gas potentially containing an ethylene concentration and ozone, a detector configured to receive light produced during a reaction between the ethylene and ozone and to produce signals related thereto, and a computer connected to the detector to process the signals to determine therefrom a value of the concentration of ethylene in the sample gas. The supply for the system can include a four way valve configured to receive pressurized gas at one input and a test chamber. A piston is journaled in the test chamber with a drive end disposed in a drive chamber and a reaction end defining with walls of the test chamber a variable volume reaction chamber. The drive end of the piston is pneumatically connected to two ports of the four way valve to provide motive force to the piston. A manifold is connected to the variable volume reaction chamber, and is configured to receive sample gasses from at least one of a plurality of ports connectable to degreening rooms and to supply the sample gas to the reactive chamber for reaction with ozone. The apparatus can be used to monitor and control the ethylene concentration in multiple degreening rooms.

Nelson, Bruce N.↗

Fluid flow rate control device

A poppet is modulated between closed and full open positions by a brushless DC motor operating magnetically through a housing to drive a permanent magnet rotor which carries the poppet. The rotor is supported on several parallel cables which are stationarily fixed at one end and attached to the rotor at the other end, whereby rotation of the rotor twists the cables, causing axial foreshortening and axial translation of rotor and poppet. Axial translation is enhanced by placing a spacer between the cables, intermediate their ends. A permanent magnet ring is disposed around the valve seat directly axially attracting the rotor to a valve closed position.

Reinicke, Robert H.↗

Liquid propellant densification

Super cooling the cryogenic liquid propellant in a vehicle propellant tank densities the propellant allowing the vehicle propellant tank to carry more fuel in the same volume tank while lowering the vapor pressure and thus the tank operating pressure. Lowering the tank operating pressure reduces the stress and therefore allows the walls of the tank to be thinner. Both the smaller tank volume and thinner tank wall results in an overall smaller and lighter vehicle with increased payload capability. The cryogenic propellant can be supercooled well below the normal boiling point temperature level by transporting the liquid propellant from the vehicle tanks to a ground based cooling unit which utilizes a combination of heat exchanger and compressor. The compressor lowers the coolant fluid bath pressure resulting in a low temperature boiling liquid which is subsequently used to cool the recirculating liquid. The cooled propellant is then returned to the vehicle propellant tank. In addition to reducing the vehicle size and weight the invention also allows location of the vent valve on the ground, elimination of on-board recirculation pumps or bleed systems, smaller and lighter engine pumps and valves, lighter and more stable ullage gas, and significant reduction in tank fill operation. All of these mentioned attributes provide lower vehicle weight and cost.

Lak, Tibor I.↗

Tapered plug foam spray apparatus

A two-component foam spray gun is readily disassembled for cleaning. It includes a body (1) with reactant (12, 14) and purge gas (16) inlet ports. A moldable valve packing (32) inside the body has a tapered conical interior surface (142), and apertures which match the reactant ports. A valve/tip (40) has a conical outer surface (48) which mates with the valve packing (32). The valve/tip (40) is held in place by a moldable packing washer (34), held at non-constant pressure by a screw (36, 38). The interior of the valve/tip (40) houses a removable mixing chamber (50). The mixing chamber (50) has direct flow orifices (60) and an auxiliary flow path (58, 60) which ameliorate pressure surges. The spray gun can be disassembled for cleaning without disturbing the seal, by removing the valve/tip (40) to the rear, thereby breaking it free of the conical packing. Rotation of the valve/tip (40) relative to the body (1) shuts off the reactant flow, and starts the purge gas flow.

Allen, Peter B.↗

Ethylene monitoring and control system

A system that can accurately monitor and control low concentrations of ethylene gas includes a test chamber configured to receive sample gas potentially containing an ethylene concentration and ozone, a detector configured to receive light produced during a reaction between the ethylene and ozone and to produce signals related thereto, and a computer connected to the detector to process the signals to determine therefrom a value of the concentration of ethylene in the sample gas. The supply for the system can include a four way valve configured to receive pressurized gas at one input and a test chamber. A piston is journaled in the test chamber with a drive end disposed in a drive chamber and a reaction end defining with walls of the test chamber a variable volume reaction chamber. The drive end of the piston is pneumatically connected to two ports of the four way valve to provide motive force to the piston. A manifold is connected to the variable volume reaction chamber, and is configured to receive sample gasses from at least one of a plurality of ports connectable to degreening rooms and to supply the sample gas to the reactive chamber for reaction with ozone. The apparatus can be used to monitor and control the ethylene concentration in multiple degreening rooms.

Nelson, Bruce N.↗

Adaptive mass expulsion attitude control system

An attitude control system and method operative with a thruster controls the attitude of a vehicle carrying the thruster, wherein the thruster has a valve enabling the formation of pulses of expelled gas from a source of compressed gas. Data of the attitude of the vehicle is gathered, wherein the vehicle is located within a force field tending to orient the vehicle in a first attitude different from a desired attitude. The attitude data is evaluated to determine a pattern of values of attitude of the vehicle in response to the gas pulses of the thruster and in response to the force field. The system and the method maintain the attitude within a predetermined band of values of attitude which includes the desired attitude. Computation circuitry establishes an optimal duration of each of the gas pulses based on the pattern of values of attitude, the optimal duration providing for a minimal number of opening and closure operations of the valve. The thruster is operated to provide gas pulses having the optimal duration.

Rodden, John J.↗

Pulse thermal loop

A pulse thermal loop heat transfer system includes a means to use pressure rises in a pair of evaporators to circulate a heat transfer fluid. The system includes one or more valves that iteratively, alternately couple the outlets the evaporators to the condenser. While flow proceeds from one of the evaporators to the condenser, heating creates a pressure rise in the other evaporator, which has its outlet blocked to prevent fluid from exiting the other evaporator. When the flow path is reconfigured to allow flow from the other evaporator to the condenser, the pressure in the other evaporator is used to circulate a pulse of fluid through the system. The reconfiguring of the flow path, by actuating or otherwise changing the configuration of the one or more valves, may be triggered when a predetermined pressure difference between the evaporators is reached.

Weislogel, Mark M.↗

Remotely controllable mixing system

A remotely controllable mixing system (210) in which a plurality of mixing assemblies (10a-10e) are arranged in an annular configuration, and wherein each assembly (10) employs a central chamber (16) and two outer, upper and lower, chambers (12, 14). Valves (18, 20) are positioned between chambers, and these valves (18, 20) for a given mixing assembly (10) are operated by upper and lower control rotors (29), which in turn are driven by upper and lower drive rotors (270, 270b). Additionally, a hoop (278) is compressed around upper control rotors (29) and a hoop (278b) is compressed around lower control rotors (29) to thus insure constant frictional engagement between all control rotors (29) and drive rotors (270, 270b). The drive rollers (270, 270b) are driven by a motor (213).

Belew, Robert R.↗

Ballast system for maintaining constant pressure in a glove box

A ballast system for a glove box including a fixed platform on which is mounted an inflatable bag on top of which resides a cover and a weight. The variable gas volume of the inflatable bag communicates with that of the glove box via a valved tube. The weight and gas volume are selected to maintain a relatively constant pressure in the glove box despite variations in the glove box volume while avoiding the use of complicated valving apparatus.

Shlichta, Paul J.↗

Apparatus for waste collection and storage

An apparatus for collection of fecal matter designed to operate efficiently in a zero gravity environment. The system comprises a waste collection area within a body having a seat opening. Low pressure within the waste collection area directs fecal matter away from the user's buttocks and prevents the escape of undesirable gases. The user actuates a piston covered with an absorbent pad that sweeps through the waste collection area to collect fecal matter, scrub the waste collector area, press the waste against an end of the waste collection area and retracts, leaving the used pad. Multiple pads are provided on the piston to accommodate multiple uses of the system. Also a valve allows air to be drawn through the body, which valve will not be plugged with fecal matter. A sheet feeder feeds fresh sheets of absorbent pad to a face of the piston with each actuation.

Thornton, Jr., William E.↗

Comparison Between Numerically Simulated and Experimentally Measured Flowfield Quantities Behind a Pulsejet

Pulsed combustion is receiving renewed interest as a potential route to higher performance in air breathing propulsion systems. Pulsejets offer a simple experimental device with which to study unsteady combustion phenomena and validate simulations. Previous computational fluid dynamic (CFD) simulation work focused primarily on the pulsejet combustion and exhaust processes. This paper describes a new inlet sub-model which simulates the fluidic and mechanical operation of a valved pulsejet head. The governing equations for this sub-model are described. Sub-model validation is provided through comparisons of simulated and experimentally measured reed valve motion, and time averaged inlet mass flow rate. The updated pulsejet simulation, with the inlet sub-model implemented, is validated through comparison with experimentally measured combustion chamber pressure, inlet mass flow rate, operational frequency, and thrust. Additionally, the simulated pulsejet exhaust flowfield, which is dominated by a starting vortex ring, is compared with particle imaging velocimetry (PIV) measurements on the bases of velocity, vorticity, and vortex location. The results show good agreement between simulated and experimental data. The inlet sub-model is shown to be critical for the successful modeling of pulsejet operation. This sub-model correctly predicts both the inlet mass flow rate and its phase relationship with the combustion chamber pressure. As a result, the predicted pulsejet thrust agrees very well with experimental data.

Geng, Tao↗

Deep-Sea Hydrothermal-Vent Sampler

An apparatus is being developed for sampling water for signs of microbial life in an ocean hydrothermal vent at a depth of as much as 6.5 km. Heretofore, evidence of microbial life in deep-sea hydrothermal vents has been elusive and difficult to validate. Because of the extreme conditions in these environments (high pressures and temperatures often in excess of 300 C), deep-sea hydrothermal- vent samplers must be robust. Because of the presumed low density of biomass of these environments, samplers must be capable of collecting water samples of significant volume. It is also essential to prevent contamination of samples by microbes entrained from surrounding waters. Prior to the development of the present apparatus, no sampling device was capable of satisfying these requirements. The apparatus (see figure) includes an intake equipped with a temperature probe, plus several other temperature probes located away from the intake. The readings from the temperature probes are utilized in conjunction with readings from flowmeters to determine the position of the intake relative to the hydrothermal plume and, thereby, to position the intake to sample directly from the plume. Because it is necessary to collect large samples of water in order to obtain sufficient microbial biomass but it is not practical to retain all the water from the samples, four filter arrays are used to concentrate the microbial biomass (which is assumed to consist of particles larger than 0.2 m) into smaller volumes. The apparatus can collect multiple samples per dive and is designed to process a total volume of 10 L of vent fluid, of which most passes through the filters, leaving a total possibly-microbe-containing sample volume of 200 mL remaining in filters. A rigid titanium nose at the intake is used for cooling the sample water before it enters a flexible inlet hose connected to a pump. As the water passes through the titanium nose, it must be cooled to a temperature that is above a mineral-precipitation temperature of 100 C but below the upper working temperature (230 C) of switching valves and tubes in the apparatus. The sample water then passes into a manifold tube, from whence the switching valves can direct the water through either a bypass tube or any one of the filter arrays, without contamination from a previous sample. Each filter array consists of series of filters having pore sizes decreasing in the direction of flow: 90-, 60-, 15-, and 7-micron prefilters and a large-surface-area 0.2-micron collection filter. All the filter taps are located between the intake and the bypass tube so that each time the bypass tube is used, the entire manifold tube is flushed as well.

Behar, Alberto E.↗

Intelligent Integrated Health Management for a System of Systems

An intelligent integrated health management system (IIHMS) incorporates major improvements over prior such systems. The particular IIHMS is implemented for any system defined as a hierarchical distributed network of intelligent elements (HDNIE), comprising primarily: (1) an architecture (Figure 1), (2) intelligent elements, (3) a conceptual framework and taxonomy (Figure 2), and (4) and ontology that defines standards and protocols. Some definitions of terms are prerequisite to a further brief description of this innovation: A system-of-systems (SoS) is an engineering system that comprises multiple subsystems (e.g., a system of multiple possibly interacting flow subsystems that include pumps, valves, tanks, ducts, sensors, and the like); 'Intelligent' is used here in the sense of artificial intelligence. An intelligent element may be physical or virtual, it is network enabled, and it is able to manage data, information, and knowledge (DIaK) focused on determining its condition in the context of the entire SoS; As used here, 'health' signifies the functionality and/or structural integrity of an engineering system, subsystem, or process (leading to determination of the health of components); 'Process' can signify either a physical process in the usual sense of the word or an element into which functionally related sensors are grouped; 'Element' can signify a component (e.g., an actuator, a valve), a process, a controller, an actuator, a subsystem, or a system; The term Integrated System Health Management (ISHM) is used to describe a capability that focuses on determining the condition (health) of every element in a complex system (detect anomalies, diagnose causes, prognosis of future anomalies), and provide data, information, and knowledge (DIaK) not just data to control systems for safe and effective operation. A major novel aspect of the present development is the concept of intelligent integration. The purpose of intelligent integration, as defined and implemented in the present IIHMS, is to enable automated analysis of physical phenomena in imitation of human reasoning, including the use of qualitative methods. Intelligent integration is said to occur in a system in which all elements are intelligent and can acquire, maintain, and share knowledge and information. In the HDNIE of the present IIHMS, an SoS is represented as being operationally organized in a hierarchical-distributed format. The elements of the SoS are considered to be intelligent in that they determine their own conditions within an integrated scheme that involves consideration of data, information, knowledge bases, and methods that reside in all elements of the system. The conceptual framework of the HDNIE and the methodologies of implementing it enable the flow of information and knowledge among the elements so as to make possible the determination of the condition of each element. The necessary information and knowledge is made available to each affected element at the desired time, satisfying a need to prevent information overload while providing context-sensitive information at the proper level of detail. Provision of high-quality data is a central goal in designing this or any IIHMS. In pursuit of this goal, functionally related sensors are logically assigned to groups denoted processes. An aggregate of processes is considered to form a system. Alternatively or in addition to what has been said thus far, the HDNIE of this IIHMS can be regarded as consisting of a framework containing object models that encapsulate all elements of the system, their individual and relational knowledge bases, generic methods and procedures based on models of the applicable physics, and communication processes (Figure 2). The framework enables implementation of a paradigm inspired by how expert operators monitor the health of systems with the help of (1) DIaK from various sources, (2) software tools that assist in rapid visualization of the condition of the system, (3) analical software tools that assist in reasoning about the condition, (4) sharing of information via network communication hardware and software, and (5) software tools that aid in making decisions to remedy unacceptable conditions or improve performance.

Smith, Harvey↗

Activation of the E1 Ultra High Pressure Propulsion Test Facility at Stennis Space Center

After a decade of construction and a year of activation the El Ultra High Pressure Propulsion Test Facility at NASA's Stennis Space Center is fully operational. The El UHP Propulsion Test Facility is a multi-cell, multi-purpose component and engine test facility . The facility is capable of delivering cryogenic propellants at low, high, and ultra high pressures with flow rates ranging from a few pounds per second up to two thousand pounds per second. Facility activation is defined as a series of tasks required to transition between completion of construction and facility operational readiness. Activating the El UHP Propulsion Test Facility involved independent system checkouts, propellant system leak checks, fluid and gas sampling, gaseous system blow downs, pressurization and vent system checkouts, valve stability testing, valve tuning cryogenic cold flows, and functional readiness tests.

Messer, Bradley↗

NASA Tech Briefs, May 2009

Topics covered include: Valve-"Health"-Monitoring System; Microstrip Antenna for Remote Sensing of Soil Moisture and Sea Surface Salinity; Biomedical Wireless Ambulatory Crew Monitor; Wireless Avionics Packet to Support Fault Tolerance for Flight Applications; Aerobot Autonomy Architecture; Submillimeter Confocal Imaging Active Module; Traveling-Wave Maser for 32 GHz; System Synchronizes Recordings from Separated Video Cameras; Piecewise-Planar Parabolic Reflectarray Antenna; Reducing Interference in ATC Voice Communication; EOS MLS Level 1B Data Processing, Version 2.2; Auto-Generated Semantic Processing Services; Geospatial Authentication; Maneuver Automation Software; Event Driven Messaging with Role-Based Subscriptions; Estimating Relative Positions of Outer-Space Structures; Fabricating PFPE Membranes for Capillary Electrophoresis; Linear Actuator Has Long Stroke and High Resolution; Installing a Test Tap on a Metal Battery Case; Fabricating PFPE Membranes for Microfluidic Valves and Pumps; Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes; Catalysts for Efficient Production of Carbon Nanotubes; Amorphous Silk Fibroin Membranes for Separation of CO2; "Zero-Mass" Noninvasive Pressure Transducers; Radial-Electric-Field Piezoelectric Diaphragm Pumps; Ejector-Enhanced, Pulsed, Pressure-Gain Combustor; Suppressing Ghost Diffraction in E-Beam-Written Gratings; Target-Tracking Camera for a Metrology System; Polarimetric Imaging using Two Photoelastic Modulators; Miniature Wide-Angle Lens for Small-Pixel Electronic Camera; Modal Filters for Infrared Interferometry; Mo(3)Sb(7-x)Te(x) for Thermoelectric Power Generation; Two-Dimensional Quantum Model of a Nanotransistor; Scanning Miniature Microscopes without Lenses; Manipulating Neutral Atoms in Chip-Based Magnetic Traps; Expansion Compression Contacts for Thermoelectric Legs; Processing Electromyographic Signals to Recognize Words; Physical Principle for Generation of Randomness; DSN Beowulf Cluster-Based VLBI Correlator; Hybrid NN/SVM Computational System for Optimizing Designs; Criteria for Modeling in LES of Multicomponent Fuel Flow; Computerized Machine for Cutting Space Shuttle Thermal Tiles; Orbiting Depot and Reusable Lander for Lunar Transportation; FPGA-Based Networked Phasemeter for a Heterodyne Interferometer; Aquarius Digital Processing Unit; Three-Dimensional Optical Coherence Tomography; Benchtop Antigen Detection Technique using Nanofiltration and Fluorescent Dyes; Isolation of Precursor Cells from Waste Solid Fat Tissue; Identification of Bacteria and Determination of Biological Indicators; Further Development of Scaffolds for Regeneration of Nerves; Chemically Assisted Photocatalytic Oxidation System; Use of Atomic Oxygen for Increased Water Contact Angles of Various Polymers for Biomedical Applications; Crashworthy Seats Would Afford Superior Protection; Open-Access, Low-Magnetic-Field MRI System for Lung Research; Microfluidic Mixing Technology for a Universal Health Sensor; Microfluidic Extraction of Biomarkers using Water as Solvent; Microwell Arrays for Studying Many Individual Cells; Droplet-Based Production of Liposomes; and Identifying and Inactivating Bacterial Spores

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