Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “gas compression”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Performance Enhancement of the Space Shuttle RSRM Nozzle-to-Case Joint Using a Carbon Rope Barrier

A carbon rope "thermal barrier" is being considered as a component to enhance performance of the Reusable Solid Rocket Motor (RSRM) nozzle-to-case joint. Fundamental performance characteristics of the rope have been considered in this paper. In particular, resistance to erosion, ability to filter particulate matter, thermal capacitance, and flow resistance have been considered. Testing results have shown the rope to be resistant to the corrosive internal environment of the RSRM. The rope has also been shown to be an effective "slag barrier." A desirable feature of the rope would be the ability to act as a heat sink. However, analyses have indicated that the thermal capacitance of the rope is not large enough to reduce the temperature of an impinging gas stream below the ablation temperature of the 0-ring for significant time periods, The real value of the rope is its ability to act as a flow diffuser. Flow resistance test, were performed on the rope In the course of testing the rope between parallel plates, an undesirable "blow-by" phenomenon was observed when the compressive stress in the rope was smaller than the upstream gas pressure. It was found, however, that in the converging passage of the actual design, the rope would consistently "Self-seat" and thereby prevent blow-by, even in the absence of any precompression. Flow resistance values have been quantified for use in future analyses. The work presented here provides an initial thermal-fluid assessment of the rope for this application, and lays the groundwork for future development.

Ewing, M. E.↗
NASA NTRSDate not supplied

Quantitation of Trace Water in ISS Atmosphere Samples Recovered from CO2-Removal Systems

As crewed spaceflight continues to push the limits of exploration, instruments and hardware used to maintain and monitor crew and vehicle health must become more integrated, reliable, and efficient. By combining a carbon dioxide (CO2) removal system with a resource recovery system like a Sabatier or Bosch reactor, the waste gas from the removal system can be converted into valuable resources that help reduce reliance on ground resupply. Due to the high-pressure nature of the Sabatier and Bosch reactions, the vent gas from most CO2 removal systems will need to be compressed before it can be processed. In order to prevent condensation in the compressor of the recovery system, it is critical to ensure that the vent stream from the CO2 removal system does not contain an excess of water. There are currently three different CO2 removal systems that are being developed as candidates for exploration missions. Each of these systems will be evaluated as a technology demonstration on ISS, and vent gas samples will be collected in Summa sampling canisters fitted with Entech valves. Due to the need to measure low levels of water in these samples, it was not possible to use the current ISS miniature grab sample containers (GSCs) to collect these samples. The Summa containers, which were used to collect archive samples during Shuttle missions, have a different surface treatment that makes it possible to measure the low levels of water in samples collected in these containers. This paper will provide some background on the CO2 removal systems being evaluated for exploration missions as well as results from ground-based testing of the current miniature GSCs and Summa canisters. Details on the development of the analytical method and the plan for preparing the canisters that will be used for in-flight sampling are also discussed.

Steven W Beck↗
NASA NTRSDate not supplied

Quantitation of Trace Water in ISS Atmosphere Samples Recovered from CO2-Removal Systems

As crewed spaceflight continues to push the limits of exploration, instruments and hardware used to maintain and monitor crew and vehicle health, must become more integrated, reliable, and efficient. By combining a carbon dioxide (CO2) removal system with a resource recovery system like a Sabatier or Bosch reactor, the waste gas from the removal system can be converted into valuable resources that help reduce reliance on ground resupply. Due to the high-pressure nature of the Sabatier and Bosch reactions, the vent gas from most CO2 removal systems will need to be compressed before it can be processed. In order to prevent condensation in the compressor of the recovery system, it is critical to ensure that the vent stream from the CO2 removal system does not contain an excess of water. There are currently two different CO2 removal systems that are being developed as candidates for exploration missions. Each of these systems will be evaluated as a technology demonstration on ISS, and vent gas samples will be collected in Summa sampling canisters fitted with Entech valves for ground analysis. Due to the need to measure low levels of water in these samples, it was not possible to use the current ISS mini-grab sample containers (m-GSC) to collect these samples. The Summa containers, which were used to collect archive samples during Shuttle missions, have a different surface treatment that makes it possible to measure the low levels of water in samples collected in these containers. This paper will provide some background on the CO2 removal systems being evaluated for exploration missions as well as results from ground-based testing of the Summa canisters. Details on the development of the analytical method and the plan for preparing the canisters that will be used for in-flight sampling are also discussed.

William M. King↗
NASA NTRS2004

Spectroscopy of the Perseus Cluster

We present preliminary results of a XMM-Newton 50 ks observation of the Perseus Cluster that provides an unprecedented view of the central 0.5 Mpc region. The projected gas temperature declines smoothly by a factor of 2 from a maximum value of approx. 7 keV in the outer regions to just above 3 keV at the cluster center. Over this same range, the heavy-element abundance rises slowly from 0.4 to 0.5 solar as the radius decreases from 14 ft. to 5 ft., and then it rises to a peak of almost 0.7 solar at 1&farcm;25 before declining to 0.4 at the center. Th global east-west asymmetry of the gas temperature and surface brightness distributions, approximately aligned with the chain of bright galaxies, suggests an ongoing merger, although the modest degree of the observed asymmetry certainly excludes a major merger interpretation. The chain of galaxies probably traces the filament along which accretion started some time ago and is continuing at the present time. A cold and dense (low-entropy) cluster core like Perseus is probably well "protected" against the penetration of the gas of infalling groups and poor clusters, whereas in non-cooling core clusters such as Coma and A1367, infalling subclusters can penetrate deeply into the core region. In Perseus, gas associated with infalling groups may be stripped completely at the outskirts of the main cluster and only compression waves (shocks) may reach the central regions. We argue, and show supporting simulations, that the passage of such a wave(s) can qualitatively explain the overall horseshoe shaped appearance of the gas temperature map (the hot horseshoe surrounds the colder, low-entropy core) as well as other features of the Perseus Cluster core. These simulations also show that as compression waves traverse the cluster core, they can induce oscillatory motion of the cluster gas that can generate multiple sharp "edges" on opposite sides of the central galaxy. Gas motions induced by mergers may be a natural way to explain the high frequency of "edges" seen in clusters with cooling cores.

Jones, Christine↗
NASA NTRS2013

Method of Separating Oxygen From Spacecraft Cabin Air to Enable Extravehicular Activities

Extravehicular activities (EVAs) require high-pressure, high-purity oxygen. Shuttle EVAs use oxygen that is stored and transported as a cryogenic fluid. EVAs on the International Space Station (ISS) presently use the Shuttle cryo O2, which is transported to the ISS using a transfer hose. The fluid is compressed to elevated pressures and stored as a high-pressure gas. With the retirement of the shuttle, NASA has been searching for ways to deliver oxygen to fill the highpressure oxygen tanks on the ISS. A method was developed using low-pressure oxygen generated onboard the ISS and released into ISS cabin air, filtering the oxygen from ISS cabin air using a pressure swing absorber to generate a low-pressure (high-purity) oxygen stream, compressing the oxygen with a mechanical compressor, and transferring the high-pressure, high-purity oxygen to ISS storage tanks. The pressure swing absorber (PSA) can be either a two-stage device, or a single-stage device, depending on the type of sorbent used. The key is to produce a stream with oxygen purity greater than 99.5 percent. The separator can be a PSA device, or a VPSA device (that uses both vacuum and pressure for the gas separation). The compressor is a multi-stage mechanical compressor. If the gas flow rates are on the order of 5 to 10 lb (.2.3 to 4.6 kg) per day, the compressor can be relatively small [3 ~16 ~16 in. (.8 ~41 ~41 cm)]. Any spacecraft system, or other remote location that has a supply of lowpressure oxygen, a method of separating oxygen from cabin air, and a method of compressing the enriched oxygen stream, has the possibility of having a regenerable supply of highpressure, high-purity oxygen that is compact, simple, and safe. If cabin air is modified so there is very little argon, the separator can be smaller, simpler, and use less power.

Graf, John C.↗
NASA NTRS1992

Effect of inert propellant injection on Mars ascent vehicle performance

A Mars ascent vehicle is limited in performance by the propellant which can be brought from Earth. In some cases the vehicle performance can be improved by injecting inert gas into the engine, if the inert gas is available as an in-situ resource and does not have to be brought from Earth. Carbon dioxide, nitrogen, and argon are constituents of the Martian atmosphere which could be separated by compressing the atmosphere, without any chemical processing step. The effect of inert gas injection on rocket engine performance was analyzed with a numerical combustion code that calculated chemical equilibrium for engines of varying combustion chamber pressure, expansion ratio, oxidizer/fuel ratio, and inert injection fraction. Results of this analysis were applied to several candidate missions to determine how the required mass of return propellant needed in low Earth orbit could be decreased using inert propellant injection.

Colvin, James E.↗
NASA NTRS2003

Computation of Pressurized Gas Bearings Using CE/SE Method

The space-time conservation element and solution element (CE/SE) method is extended to compute compressible viscous flows in pressurized thin fluid films. This numerical scheme has previously been used successfully to solve a wide variety of compressible flow problems, including flows with large and small discontinuities. In this paper, the method is applied to calculate the pressure distribution in a hybrid gas journal bearing. The formulation of the problem is presented, including the modeling of the feeding system. the numerical results obtained are compared with experimental data. Good agreement between the computed results and the test data were obtained, and thus validate the CE/SE method to solve such problems.

Cioc, Sorin↗
NASA NTRS1993

Particle-Gas Dynamics in the Midplane of a Protoplanetary Nebula

In this paper, we study the stage of planetary formation during which the particulate material is still dispersed as centimeter-to-meter sized primordial aggregates. During this stage, particles are able to settle toward the midplane into a layer of mass density comparable to or much greater than that of the gas. Nonlinear, coupled interactions between the particles and the nebula gas become significant and ultimately determine the vertical profiles of the particle density and the mean velocities of the particles and the nearby gas. This is the environment in which the earliest planetesimals probably form. Our numerical models rely on the Reynolds averaged Navier-Stokes equations for the gas and particles and are fully viscous and turbulent (and, for the particles. compressible). Our turbulence modeling uses a Prandtl local shear parametrization, validated by laboratory experiments. We have developed a new model for particle diffusion involving the profile of the nebula gas turbulence and the particle Schmidt number, which is a function of particle size and density. We model a cool, quiescent nebula at 1 AU (280 K) and 10 AU (90 K) and a higher temperature stage (1000 K) at 1 AU. Our main results include: (a) rapid accretion of planetesimals by gravitationally unstable fragmentation on an orbital time scale (the 'Goldreich-Ward instability') is unlikely to occur until objects have already accreted by some other process to the mass of the largest known meteorite samples, if at all; (b) from 'seeds' as small as 10 m, growth of 10- to 100-km planetesimals can proceed rapidly by drift-augmented accretion in the particle-rich midplane with orbital decay of about 1% for the growing planetesimals; (c) outward transport of vapor and small entrained chips can account for significant radial compositional and mineralogical mixing in primitive meteorite parent bodies. Other implications may be drawn concerning particle random collisional velocities and the time scales of midplane turbulence.

Cuzzi, Jeffrey N.↗
NASA NTRS1966

Improved tool easily removes brazed tube connectors

Portable, compact tool quickly and cleanly removes brazed connectors from system tubes. The tool uses an induction coil to melt the braze and a compression spring to automatically separate the connection. An inert gas is force-fed about the heated area to prevent oxidation of the tube.

Schoppman, R. A.↗
NASA NTRS1972

Computer program for natural gas flow through nozzles

Subroutines, FORTRAN 4 type, were developed for calculating isentropic natural gas mass flow rate through nozzle. Thermodynamic functions covering compressibility, entropy, enthalpy, and specific heat are included.

Johnson, R. C.↗
NASA NTRS1977

Liquid-hydrogen boiloff reliquifier

Device uses Joule-Thomson expansion and pressure-relief cooling of compressed and cooled boiloff hydrogen to condense portion of gas. System could be used with cryogens such as helium, nitrogen, and oxygen.

Howard, F. S.↗
NASA NTRS1990

Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems, task 1: Ducted propfan analysis

The time-dependent three-dimensional Euler equations of gas dynamics were solved numerically to study the steady compressible transonic flow about ducted propfan propulsion systems. Aerodynamic calculations were based on a four-stage Runge-Kutta time-marching finite volume solution technique with added numerical dissipation. An implicit residual smoothing operator was used to aid convergence. Two calculation grids were employed in this study. The first grid utilized an H-type mesh network with a branch cut opening to represent the axisymmetric cowl. The second grid utilized a multiple-block mesh system with a C-type grid about the cowl. The individual blocks were numerically coupled in the Euler solver. Grid systems were generated by a combined algebraic/elliptic algortihm developed specifically for ducted propfans. Numerical calculations were initially performed for unducted propfans to verify the accuracy of the three-dimensional Euler formulation. The Euler analyses were then applied for the calculation of ducted propfan flows, and predicted results were compared with experimental data for two cases. The three-dimensional Euler analyses displayed exceptional accuracy, although certain parameters were observed to be very sensitive to geometric deflections. Both solution schemes were found to be very robust and demonstrated nearly equal efficiency and accuracy, although it was observed that the multi-block C-grid formulation provided somewhat better resolution of the cowl leading edge region.

Hall, Edward J.↗
NASA NTRS1992

Advanced ramjet concepts program

Uniquely advantageous features, on both the performance and weight sides of the ledger, can be achieved through synergistic design integration of airbreathing and rocket technologies in the development of advanced orbital space transport propulsion systems of the combined cycle type. In the context of well understood advanced airbreathing and liquid rocket propulsion principles and practices, this precept of synergism is advanced mainly through six rather specific examples. These range from the detailed component level to the overall vehicle system level as follows: using jet compression; achieving a high area ratio rocket nozzle; ameliorating gas generator cycle rocket system deficiencies; using the in-duct special rocket thrust chamber assembly as the principal scramjet fuel injection operation; using the unstowed, covered fan as a duct closure for effecting high area ratio rocket mode operation; and creating a unique airbreathing rocket system via the onboard, cryogenic hydrogen induced air liquefaction process.

Leingang, J. L.↗
NASA NTRS2004

The Effect of Large Melt Fraction on the Deformation Behavior of Peridotite: Implications for the Rheology of Io' Mantle

One key constraint needed for refinement of the interior geochemical and geodynamic models of Io is the viscosity of the convecting partially- molten silicate mantle. To date, laboratory studies of partially molten mantle rocks have reached melt fractions up to approx.0.12, a value much smaller than thought to be appropriate for the asthenosphere of Io where the degree of partial melting may be 0.15 0.40 or higher. Therefore, we have performed a series of high temperature, triaxial compressive creep experiments on dry synthetic peridotites in a gas medium apparatus at a confining pressure of 300 MPa and temperatures from 1473 to 1573 K in order to understand the influence of large amounts of melt (0.15 < phi < 0.40) on the rheological behavior of partially molten rocks.

Scott, T.↗
NASA NTRSDate not supplied

Assessment of Using Ideal Gas for Predicting Boattail Flow at Cryogenic Temperatures

The applicability of using ideal gas assumptions to simulate high Reynolds number experimental data that was obtained at cryogenic temperatures is examined. Flow over an axisymmetric nozzle boattail model was calculated using reference temperatures of 117 K and 300 K and at Reynolds numbers from 50 to 200 million per meter. From the testing perspective, pressure, compression factor, and isentropic coefficients calculated using one-dimensional real gas equations are used to examine the departure of cryogenic flow from ideal gas flow across the range of temperatures and potential impacts on measured aerodynamic data. Solutions developed using ideal gas assumptions in a three-dimensional Navier-Stokes code are compared with experimental data obtained at cryogenic temperatures at two unit Reynolds numbers at freestream Mach numbers of 0.6 and 0.9. Results for several one- and two-equation turbulence models are shown. Predicted pressure coefficient distributions along the nozzle boattail differed from experimental data between 8% to less than 0.5% depending on the turbulence model and Mach number. The greatest discrepancy occurred in the level of static pressure recovery in the recompression region where the flow was separated. Solutions using warm and cryogenic freestream temperatures predicted similar boattail pressure distributions at the same unit Reynolds number.

Nozzle↗
NASA NTRSDate not supplied

Assessment of Using Ideal Gas for Predicting Boattail Flow at Cryogenic Temperatures

The applicability of using ideal gas assumptions to simulate high Reynolds number experimental data that was obtained at cryogenic temperatures is examined. Flow over an axisymmetric nozzle boattail model was calculated using reference temperatures of 117 K and 300 K and at Reynolds numbers from 50 to 200 million per meter. From the testing perspective, pressure, compression factor, and isentropic coefficients calculated using one-dimensional real gas equations are used to examine the departure of cryogenic flow from ideal gas flow across the range of temperatures and potential impacts on measured aerodynamic data. Solutions developed using ideal gas assumptions in a three-dimensional Navier-Stokes code are compared with experimental data obtained at cryogenic temperatures at two unit Reynolds numbers at freestream Mach numbers of 0.6 and 0.9. Results for several one- and two-equation turbulence models are shown. Predicted pressure coefficient distributions along the nozzle boattail differed from experimental data between 8% to less than 0.5% depending on the turbulence model and Mach number. The greatest discrepancy occurred in the level of static pressure recovery in the recompression region where the flow was separated. Solutions using warm and cryogenic freestream temperatures predicted similar boattail pressure distributions at the same unit Reynolds number.

Nozzle↗