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Results for “PRESSURE APPARATUS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Apparatus and method for jet noise suppression

A method and apparatus for jet noise suppression through control of the static pressure of the jet and control of the rate of entrainment of ambient fluid into the jet downstream of the exhaust nozzle is disclosed. The momentum flux over an extended region of the jet is regulated, affecting Reynolds stresses in the jet and the spreading angle of the jet. Static pressure is controlled through a long hollow, porous nozzle plug centerbody which may be selectively vented to ambient conditions, connected to a vacuum source, or supplied with fluids of various densities for injection into the stream. Sound in the jet may be channeled along the nozzle plug centerbody by injecting coolant such as a cryogenic fluid throughout the center-body into the jet.

Maestrello, L.↗
NASA NTRS1990

Automatic Refilling System For Liquid Helium

Cryogenic experiments left unattended for days. System automatically replenishes liquid helium in cryogenic experimental apparatus as liquid evaporates. Automatic filling system transfers liquid helium from storage vessel to experimental apparatus under computer control. Gaseous helium from cylinder supplies pumping pressure. Circuit senses level of liquid helium by sensing voltage across measuring resistors in series with silicon resistance thermometers (SRT's). Low voltage indicates SRT covered, while high voltage indicates uncovered.

Serlemitsos, Aristides↗
NASA NTRS1989

Aeolian processes on Venus

This review assesses the potential aeolian regime on Venus as derived from spacecraft observations, laboratory simulations, and theoretical considerations. The two requirements for aeolian processes (a supply of small, loose particles and winds of sufficient strength to move them) appear to be met on Venus. Venera 9, 10, 13, and 14 images show particles considered to be sand and silt size on the surface. In addition, dust spurts (grains 5 to 50 microns in diameter) observed via lander images and inferred from the Pioneer-Venus nephalometer experiments suggest that the particles are loose and subject to movement. Although data on near surface winds are limited, measurements of 0.3 to 1.2 m/sec from the Venera lander and Pioneer-Venus probes appear to be well within the range required for sand and dust entrainment. Aeolian activity involves the interaction of the atmosphere, lithosphere, and loose particles. Thus, there is the potential for various physical and chemical weathering processes that can effect not only rates of erosion, but changes in the composition of all three components. The Venus Simulator is an apparatus used to simulate weathering under venusian conditions at full pressure (to 112 bars) and temperature (to 800 K). In one series of tests, the physical modifications of windblown particles and rock targets were assessed and it was shown that particles become abraded even when moved by gentle winds. However, little abrasion occurs on the target faces. Thus, compositional signatures for target rocks may be more indicative of the windblown particles than of the bedrock. From these and other considerations, aeolian modifications of the venusian surface may be expected to occur as weathering, erosion, transportation, and deposition of surficial materials. Depending upon global and local wind regimes, there may be distinctive sources and sinks of windblown materials. Radar imaging, especially as potentially supplied via the Magellan mission, may enable the identification of such areas on Venus.

Greeley, Ronald↗
NASA NTRS1987

High-speed code validation

The topics are presented in viewgraph form and include the following: NFL body experiment; high-speed validation problems; 3-D Euler/Navier-Stokes inlet code; two-strut inlet configuration; pressure contours in two longitudinal planes; sidewall pressure distribution; pressure distribution on strut inner surface; inlet/forebody tests in 60 inch helium tunnel; pressure distributions on elliptical missile; code validations; small scale test apparatus; CARS nonintrusive measurements; optimized cone-derived waverider study; etc.

Barnwell, Richard W.↗
NASA NTRS2001

Fourier Transform Infrared Spectroscopy of CF4 on the GEC Reference Cell

Fourier Transform Infrared Spectroscopy (FTIR) has been used to characterize inductively coupled CF4 plasmas in a GEC Reference Cell in-situ In examining these FTIR spectra, several assumptions and approximations of FTIR analysis are addressed. This includes the density dependence of cross-sections, non-linear effects in the addition of overlapping bands and the effect of spatial variations in density and temperature, This analysis demonstrates that temperatures extracted from MR spectra may provide a poor estimate of the true neutral plasma temperature. The FTIR spectra are dominated by unreacted CF, accounting for 40-60% of the gas products. The amount of CF4 consumption is found to have a marked dependence on power, and is nearly independent of pressure in the range of 10-50 mtorr. Small amounts of C2F6 are observed at low power. Also observed are etching products from the quartz window SiF4 COF2 and CO which occur in approximately equal ratios and together account for less than 10% of the gas. The concentrations of these species are nearly independent of pressure. CFx radicals are below the detection limit of this apparatus (approx. 1012/cc).

Rao, M. V. V. S.↗
NASA NTRS2003

High Temperature Permeability of Carbon Cloth Phenolic Composite

The carbon fiber phenolic resin composite material used for the RSRM nozzle insulator occasionally experiences problems during operation from pocketing or spalling-like erosion and lifting of plies into the char layer. This phenomenon can be better understood if the permeability of the material at elevated temperatures is well defined. This paper describes an experimental approach to determining high temperature permeability of the carbon phenolic material used as the RSRM nozzle liner material. Two different approaches were conducted independently using disk and bar type specimens with the designed permeability apparatus. The principle of the apparatus was to subject a test specimen to a high pressure differential and a heat supply and to monitor both the pressure and temperature variations resulting from gas penetration through the permeable wall between the two chambers. The bar types, especially designed to eliminate sealing difficulties at a high temperature environment, were directly exposed to real time temperature elevation from 22 C to 260 C during the test period. The disk types were pre-heat treated up to 300 C for 8 hours and cooled to room temperature before testing. Nonlinear variation of downstream pressure at a certain temperature range implied moisture release and matrix pyrolysis. Permeability was calculated using a semi-numerical model of quasi-steady state. The test results and the numerical model are discussed in the paper.

Park, O. Y.↗
NASA NTRS1987

Planar oscillatory stirring apparatus

Apparatus (11) for applying planar oscillations to a container (13). Pressurized air (99) is supplied to a moveable slide plate (27) which employs arms (19) having an air bearing vent structure (29, 31) which allows the slide plate to float and to translate. The container (13) to be oscillated is secured to the upper surface of the slide plate (27). A motor (39) driven rotating eccentric shaft (59) loosely extends into a center hole bearing (37) of the slide plate (27) to cause the oscillations.

Wolf, Martin F.↗
NASA NTRS2010

Methods and apparatus for determining cardiac output

The present invention provides methods and apparatus for determining a dynamical property of the systemic or pulmonary arterial tree using long time scale information, i.e., information obtained from measurements over time scales greater than a single cardiac cycle. In one aspect, the invention provides a method and apparatus for monitoring cardiac output (CO) from a single blood pressure signal measurement obtained at any site in the systemic or pulmonary arterial tree or from any related measurement including, for example, fingertip photoplethysmography.According to the method the time constant of the arterial tree, defined to be the product of the total peripheral resistance (TPR) and the nearly constant arterial compliance, is determined by analyzing the long time scale variations (greater than a single cardiac cycle) in any of these blood pressure signals. Then, according to Ohm's law, a value proportional to CO may be determined from the ratio of the blood pressure signal to the estimated time constant. The proportional CO values derived from this method may be calibrated to absolute CO, if desired, with a single, absolute measure of CO (e.g., thermodilution). The present invention may be applied to invasive radial arterial blood pressure or pulmonary arterial blood pressure signals which are routinely measured in intensive care units and surgical suites or to noninvasively measured peripheral arterial blood pressure signals or related noninvasively measured signals in order to facilitate the clinical monitoring of CO as well as TPR.

Cohen, Richard J.↗
NASA NTRS2023

Fitting Leak Test Report: Ground-Based Cryogenic Leak Test of Fittings for Cryogenic Fluid Management

EXECUTIVE SUMMARY Mechanically connected joints used in cryogenic fluid lines as part of space flight elements need to survive launch vibrations and remain leak-free to minimize the loss of on-board commodity and hazardous gas accumulation. In 2020, a cryogenic test apparatus was developed which can evaluate the leak performance of pressurized threaded fluid fittings. The fittings were mounted in the TVAC and cooled to cryogenic test temperature and pressurized with helium while the leak rate was measured using a calibrated GHe leak detector. The test articles for the initial proof of concept testing were ¼ and 1 inch Swagelok VCR fittings with three different types of seal rings copper, nickel, and Ni. Each fitting configuration (size/seal material) was subjected to two consecutive cryogenic thermal cycles, followed by exposure to a launch vibration profile at ambient temperature, after which two additional TVAC cycle tests were performed. The testing reported here is a continuation of the 2020 tests with a statistically significant large number of samples and test runs. Three Swagelok VCR fitting sizes were tested ¼, ½ and 1 inch, and five (5) samples of each fitting size, each sample was tested with SST and Ni seal rings (Total of 30 unique test articles). Each test article was subjected to four (4) thermal cycles. Half of these cycles were performed before vibration testing and half were performed after vibration testing. The vibration testing was performed to evaluate the ability of the fittings to survive launch-type vibration profiles and remain leak-free. Leak checking of each fitting was completed at temperatures between 20K – 30K. The test procedure in Section 8.0 was designed to facilitate a qualification test program by allowing a higher test throughput rate coupled with repeatable test profiles. Results were very positive and show that out of the 30 samples they all passed with leak rates a factor of 2-3 lower than the established 10-6sccs GHe leak threshold. The result showed the Ni seals had lower leak rate, but the SST was more rugged. There were two deviations where damage to the Ni seal ring during assembly resulted in a leaky fitting, this is discussed in Section 10.7 Test Deviations. These fittings show great promise for space flight use and further testing is recommended to fully qualify the fittings per the ASTM F1387-19 and/or other relevant NASA specifications. The test equipment hardware and software capability developed for this testing is generic and not restricted to VCR fittings. It can be employed to evaluate/qualify the leak performance of other types of fittings and a wide range of other cryogenic fluid components such as valves, gages, connectors, etc.

Cryogenic↗
NASA NTRS2011

Measurement of Apparent Thermal Conductivity of JSC-1A Under Ambient Pressure

The apparent thermal conductivity of JSC-1A lunar regolith simulant was measured experimentally using a cylindrical apparatus. Eleven thermocouples were embedded in the simulant bed to obtain the steady state temperature distribution at various radial, axial, and azimuthal locations. The high aspect ratio of a cylindrical geometry was proven to provide a one-dimensional, axisymmetric temperature field. A test series was performed at atmospheric pressure with varying heat fluxes. The radial temperature distribution in each test fit a logarithmic function, indicating a constant thermal conductivity throughout the soil bed. However, thermal conductivity was not constant between tests at different heat fluxes. This variation is attributed to stresses created by thermal expansion of the simulant particles against the rigid chamber wall. Under stress-free conditions (20 deg C), the data suggest a temperature independent apparent conductivity of 0.1961 +/- 0.0070 W/m/ deg C

Yuan, Zeng-Guang↗
DOE OSTI2024

A miniature multi-anvil apparatus using diamond as anvils—MDAC: Multi-axis diamond anvil cell

The diamond anvil cell (DAC) has been widely used in high-pressure research. Despite significant progress over the past five decades, the opposed anvil geometry in the DAC inevitably leads to a disk-shaped sample configuration at high pressure. This intrinsic limitation is largely responsible for the large pressure and temperature gradients in the DAC, which often compromise precise experiments and their characterizations. Here, we designed and fabricated a multi-axis diamond anvil cell (MDAC) by adopting the concept of a multi-anvil apparatus but using single crystal diamonds as the anvil material. Preliminary data show that the MDAC can generate extreme pressure conditions above 100 GPa. The advantages of the MDAC over a traditional opposed anvil DAC include thicker, voluminous samples, quasi-hydrostatic, or designed deviatoric stress conditions, and multidirectional access windows for optical applications and x-ray probes. In this article, we present the design and performance of a prototype MDAC, as well as the application prospects in high-pressure research.

47 OTHER INSTRUMENTATION↗
NASA NTRS1985

Moisture content and gas sampling device

An apparatus is described for measuring minute quantities of moisture and other contaminants within sealed enclosures such as electronic assemblies which may be subject to large external atmospheric pressure variations. An array of vacuum quality valves is arranged to permit cleansing of the test apparatus of residual atmospheric components from a vacuum source. This purging operation evacuates a gas sample bottle, which is then connected by valve settings to provide the drive for withdrawing a gas sample from the sealed enclosure under test into the sample bottle through a colometric detector tube (Drager tube) which indicates moisture content. The sample bottle may be disconnected and its contents (drawn from the test enclosure) separately subjected to mass spectrograph analysis.

Krieg, H. C., Jr.↗
NASA NTRS1989

Apparatus for measuring high-flux heat transfer in radiatively heated compact exchangers

An apparatus is described which can deliver uniform heat flux densities of up to 80 W/sq cm over an area 7.8 cm x 15.2 cm for use in measuring the heat transfer and pressure drop in thin (6 mm or less), compact heat exchangers. Helium gas at flow rates of 0 to 40 kg/h and pressures to 6.9 MPa (1000 psi) is the working fluid. The instrumentation used in the apparatus and the methods for analyzing the data is described. The apparatus will be used initially to test the performance of prototype cooling jackets for the engine struts of the National Aerospace Plane (NASP).

Olson, Douglas A.↗
NASA NTRS1982

Method and apparatus for producing gas-filled hollow spheres

A system for forming hollow spheres containing pressured gas is described which includes a cylinder device containing a molten solid material with a nozzle at its end. A second gas nozzle, lying slightly upstream from the tip of the first nozzle, is connected to a source that applies pressured filler gas that is to fill the hollow spheres. High pressure is applied to the molten metal, as by moving a piston within the cylinder device, to force the molten material out of the first nozzle. At the same time, pressured gas fills the center of the extruded hollow liquid pipe that breaks into hollow spheres. The environment outside the nozzles contains gas at a high pressure such as 100 atmospheres. Gas is supplied to the gas nozzle at a slightly higher pressure such as 101 atmospheres. The pressure applied to the molten material is at a still higher pressure such as 110 atmospheres.

Wang, T. G.↗
NASA NTRS2001

Aerodynamic Measurements on a Large Splitter Plate for the NASA Langley Transonic Dynamics Tunnel

Tests conducted in the NASA Langley Research Center Transonic Dynamics Tunnel (TDT) assess the aerodynamic characteristics of a splitter plate used to test some semispan models in this facility. Aerodynamic data are analyzed to determine the effect of the splitter plate on the operating characteristics of the TDT, as well as to define the range of conditions over which the plate can be reasonably used to obtain aerodynamic data. Static pressures measurements on the splitter plate surface and the equipment fairing between the wind tunnel wall and the splitter plate are evaluated to determine the flow quality around the apparatus over a range of operating conditions. Boundary layer rake data acquired near the plate surface define the viscous characteristics of the flow over the plate. Data were acquired over a range of subsonic, transonic and supersonic conditions at dynamic pressures typical for models tested on this apparatus. Data from this investigation should be used as a guide for the design of TDT models and tests using the splitter plate, as well as to guide future splitter plate design for this facility.

Schuster, David M.↗
NASA NTRS2011

Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System

Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper.

Lynn, Keith C.↗
NASA NTRS2001

Droplet Combustion in a Slow Convective Flow

The objective of the present flight experiment definition study is to investigate the effects of slow forced convective flows on the dynamics of isolated single droplet combustion and is designed to complement the quiescent, microgravity droplet combustion experiments (DCE-1 and DCE-2) of Williams and Dryer. The fuels selected for this study are the same as those of DCE, namely, a sooting alkane fuel (heptane) and a non-sooting alcohol (methanol), and imposed flow rates are chosen between 0 and 20 cm/s with varying ambient oxygen concentrations and pressures. Within this velocity range, both accelerating and decelerating flow effects will also be investigated. Two different approaches to generate the forced flow are currently under development in ground-based facilities; the first is a flow tunnel concept where the forced flow is imposed against a stationary droplet, and in the second a tethered droplet is translated at a specified velocity in a quiescent ambient medium. Depending upon the engineering feasibility a selection will be made between these two approaches so that the experiment can be accommodated in the Multiple Droplet Combustion Apparatus (MDCA) currently being designed for the International Space Station. Recently, we have finished designing and fabricating the experimental rigs using both the above mentioned concepts. The flow tunnel concept is implemented in a 2.2 second drop tower rig. Preliminary experiments have been carried out using heptane and methanol in air at atmospheric pressure. The translating droplet apparatus is scheduled to be tested in the 5 second drop facility in the near future. This report presents some of the experimental results obtained for heptane.

Nayagam, V.↗