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The synthesis and characterization of Fe-bearing phase E and phase E' demonstrate that the phase E-type structures can be rather compliant and complex, and that as we further explore the temperature-pressure-composition space, other types of structures that are similar to or related to the structure of phase E may be discovered.
In an effort to develop harsh environment electronic and sensor technologies for aircraft engine safety and monitoring, we have used capacitive-based pressure sensors to shift the frequency of a SiC-electronics-based oscillator to produce a pressure-indicating signal that can be readily transmitted, e.g. wirelessly, to a receiver located in a more benign environment. Our efforts target 500 C, a temperature well above normal operating conditions of commercial circuits but within areas of interest in aerospace engines, deep mining applications and for future missions to the Venus atmosphere. This paper reports for the first time a ring oscillator circuit integrated with a capacitive pressure sensor, both operating at 500 C. This demonstration represents a significant step towards a wireless pressure sensor that can operate at 500 C and confirms the viability of 500 C electronic sensor systems.
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Theoretical and experimental studies on high pressure electrolysis producing hydrogen and oxygen for energy storage and reconversion are reported. Moderate temperature, high pressure hydrogen/oxygen fuel cells with nickel electrodes are investigated for effects of pressure, temperature, and membrane porosity. Test results from an aphodid burner turbine generator combination obtained 40 percent kilowatt hours out of the fuel cell divided by kilowatt hours into the electrolyzer. It is concluded that high pressure hydrogenation of organic materials can be used to synthesize hydrozenes and methanes for making synthetic vehicular fuels.
Vapor pressure curves of low melting metals for selection of high temperature sensor device
A process for manufacturing bulk diamond has been made practical by the invention of the High Pressure and Temperature Apparatus capable of applying the combination of very high temperature and high pressure needed to melt carbon in a sufficiently large volume. The apparatus includes a reaction cell wherein a controlled static pressure as high as 20 GPa and a controlled temperature as high as 5,000 C can be maintained.
Temperature profile calculations for high pressure electric arcs using diffusion approximation for radiant flux density, taking energy transfer into account
Solid polymer electrolyte technology used in a water electrolysis system (WES) to generate oxygen and hydrogen for manned space station applications was investigated. A four-man rated, low pressure breadboard water electrolysis system with the necessary instrumentation and controls was fabricated and tested. A six man rated, high pressure, high temperature, advanced preprototype WES was developed. This configuration included the design and development of an advanced water electrolysis module, capable of operation at 400 psig and 200 F, and a dynamic phase separator/pump in place of a passive phase separator design. Evaluation of this system demonstrated the goal of safe, unattended automated operation at high pressure and high temperature with an accumulated gas generation time of over 1000 hours.
The feasibility of measuring temperatures in the space shuttle main engine (SSME) fuel preburner using spontaneous Raman scattering from molecular hydrogen was studied. Laser radiation is transmitted to the preburner through a multimode optical fiber. Backscattered Raman-shifted light is collected and focused into a second fiber which connects to a remote-located spectrograph and a mutlichannel optical detector. Optics collimate and focus laser light from the transmitter fiber defining the probe volume. The high pressure, high temperature preburner environment was simulated by a heated pressure cell. Temperatures determined by the distribution of Q-branch co-vibrational transitions demonstrate precision and accuracy of 3%. It is indicated heat preburner temperatures can be determined with 5% accuracy with spatial resolution less than 1 cm and temporal resolution of 10 millisec at the nominal preburner operation conditions.
Ceramic-fibers brush and integral spring clip block hot, engine flows. High-temperature, pressure-assisted brush seal installed in movable panel in advanced hypersonic engine. Seal prevents flow of hot engine gas from penetrating gap between movable panel and adjacent stationary panel. Potential applications include sealing gaps in variable-geometry two-dimensional turbojet exhaust nozzles or sealing control surface gaps of hypersonic vehicles. Ceramic brush seals also used as structural seals in high-temperature furnaces or advanced ceramic heat exchangers.
Supercritical droplet vaporization is an important issue in many combustion systems, such as liquid fueled rockets and compression-ignition (diesel) engines. In order to study the details of droplet behavior at these conditions, an experiment was designed to provide a gas phase environment which is above the critical pressure and critical temperature of a single liquid droplet. In general, the droplet begins as a cold droplet in the hot, high pressure environment. In order to eliminate disruptions to the droplet by convective motion in the gas, forced and natural convection gas motion are required to be small. Implementation of this requirement for forced convection is straightforward, while reduction of natural convection is achieved by reduction in the g-level for the experiment. The resulting experiment consists of a rig which can stably position a droplet without restraint in a high-pressure, high temperature gas field in microgravity. The microgravity field is currently achieved by dropping the device in the NASA Lewis 2.2 second drop tower. The performance of the experimental device and results to date are presented.
The objective of this research is to obtain an improved understanding of the behavior of droplets in vaporizing sprays, particularly under conditions typical of those in high pressure rocket sprays. Experiments are conducted in a variety of high pressure, high temperature, optically-accessible flow systems, including one which is capable of operation at pressures up to 70 atm, temperatures up to 600 K, gas velocities up to 30 m/sec and turbulence intensities up to 40 percent. Single droplets, 50 to 500 micron in diameter, are produced by an aerodynamic droplet generator and transversely injected into the flow. Measurements are made of the droplet position, size, velocity and temperature and of the droplet's vapor wake from which droplet drag, dispersion, heating, vaporization and breakup are characterized.
Results of holographic flow visualization from tests made in the Langley 0.3 meter transonic cryogenic tunnel are presented. The tunnel was operated over a temperature range from 100 to 300 K and a pressure range from 1.1 to 4 atm. Interferometry at the facility may be of limited use at the low temperature high pressure conditions because of the jumbled nature of the reference fringes. The shadowgraph technique appears to be the best means of visualizing shocks at these high density conditions. The spot size at the focus of the reconstructed beams was measured and used as an indicator of density fluctuations in the flow field. These density fluctuations appear to be caused by temperature fluctuations of the test gas which are relatively independent of tunnel conditions.
Results of holographic flow visualization from tests made in the Langley 0.3 meter transonic cryogenic tunnel are presented. The tunnel was operated over a temperature range from 100 to 300 K and a pressure range from 1.1 to 4 atm. Interferometry at the facility may be of limited use at the low temperature high pressure conditions because of the jumbled nature of the reference fringes. The shadowgraph technique appears to be the best means of visualizing shocks at these high density conditions. The spot size at the focus of the reconstructed beams was measured and used as an indicator of density fluctuations in the flow field. These density fluctuations appear to be caused by temperature fluctuations of the test gas which are relatively independent of tunnel conditions.
The Advanced Subsonic Combustor Rig (ASCR) is NASA Glenn Research Center's unique high-pressure, high-temperature combustor facility supporting the emissions reduction element of the Ultra-Efficient Engine Technology (UEET) Project. The facility can simulate combustor inlet test conditions up to a pressure of 900 psig and a temperature of 1200 F (non-vitiated). ASCR completed three sector tests in fiscal year 2003 for General Electric, Pratt & Whitney, and Rolls-Royce North America. This will provide NASA and U.S. engine manufacturers the information necessary to develop future low-emission combustors and will help them to better understand durability and operability at these high pressures and temperatures.
The origin of volatile elements in the Earth, Moon and Mars is not known; however, several theories have been proposed based on volatile elements such as In, As, Se, Te and Zn which are in lower concentration in the Earth, Moon, and Mars than in chondrites. Explanations for these low concentrations are based on two contrasting theories for the origin of Earth: equilibrium core formation versus late accretion. One idea is that the volatiles were added during growth of the planets and Moon, and some mobilized into the metallic core while others stayed in the mantle (e.g., [1]). The competing idea is that they were added to the mantles after core formation had completed (e.g., [2]). Testing these ideas involves quantitative modeling which can only be performed after data is obtained on the systematic metal-silicate partitioning behavior of volatile elements with temperature, pressure and melt composition. Until now, such data for Bi, In, and Cd has been lacking. After conducting a series of high pressure, high temperature experiments, the metal-silicate partition coefficients of Bi, In, and Cd as a function of temperature and melt composition can be used to evaluate potential conditions under which terrestrial planets differentiated into core and mantle, and how they acquired volatiles.
Conventional and advanced gas turbine engines are coming under increased scrutiny regarding pollutant emissions. This, in turn, has created a need to obtain in-situ experimental data at practical conditions, as well as exhaust data, and to obtain the data in combustors that reflect modern designs. The in-situ data are needed to (1) assess the effects of design modifications on pollutant formation, and (2) develop a detailed data base on combustor performance for the development and verification of computer modeling. This paper reports on a novel high pressure, high temperature facility designed to acquire such data under controlled conditions and with access (optical and extractive) for in-situ measurements. To evaluate the utility of the facility, a model gas turbine combustor was selected which features practical hardware design, two rows of jets (primary and dilution) with four jets in each row, and advanced wall cooling techniques with laser drilled effusive holes. The dome is equipped with a flat-vaned swirler with vane angles of 60 degrees. Data are obtained at combustor pressures ranging from 2 to 10 atmospheres of pressure, levels of air preheat to 427 C, combustor reference velocities from 10.0 to 20.0 m/s, and an overall equivalence ratio of 0.3. Exit plane and in-situ measurements are presented for HC, O2, CO2, CO, and NO(x). The exit plane emissions of NO(x) correspond to levels reported from practical combustors and the in-situ data demonstrate the utility and potential for detailed flow field measurements.
The advanced regeneratively cooled rocket thrust chamber may require new materials to achieve long life and improved performance. Current materials such as NARloy-Z (Cu-3 wt. percent Ag-0.5 wt. percent Zr), while highly conductive, do not have sufficient high temperature strength and creep resistance to meet the projected needs of advanced rocket motors. A Cu-8 at. percent Cr-4 at. percent Nb (Cu-8 Cr-4 Nb) alloy has been identified as a promising material for this application. However, hydrogen embrittlement is a concern given the presence of high pressure, high temperature hydrogen in regeneratively cooled rocket motors. Thermodynamic analysis of the reaction between Cr-rich Cr2Nb and H2 showed that there is a possibility of reaction at temperatures up to 323 K in a 35 MPa H2 environment. Above 323 K the pressure necessary to achieve reaction rapidly increased beyond the range experienced in rocket motors. Tensile specimens exposed in 34.5 MPa H2 at room temperatures and during cycling to 705 C did not show any degradation of properties. No evidence of reaction was observed for Cr2Nb precipitate observed on the fracture surfaces. Based on these results the Cu-8 Cr-4 Nb alloy was judged to be sufficiently stable for use in rocket motors.