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At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Evaluation of a hydrogen chloride detector for environmental monitoring

The paper describes a hydrogen chloride detector designed to monitor concentrations of hydrogen chloride gas in the ambient environment. The detector was developed for NASA for use in launch vehicle effluent monitoring. The detector operates on chemiluminescence principles with a lower detection limit of less than 5 x 10 to the -3rd ppm (by volume). The hydrogen chloride in the air sample reacts with a bromide-bromate coating in the inlet tube of the instrument producing bromine. Bromine is then quantitated by chemiluminescent oxidation of luminol. The visible light generated in the chemiluminescent reaction is proportional to the hydrogen chloride concentration of the sampled airstream. The detector is most suited to laboratory or field studies where hydrogen chloride is the dominant pollutant, as compared to the interfering species. Interferences include strong acids, acid-forming gases, and halogen gases. Of the interferences investigated the most serious in these groups are hydrochloric and sulfuric acid, sulfur dioxide, and chlorine, respectively. The detector has been in use since 1974 and has been found to be highly portable, rugged, and stable under extreme environmental conditions.

Gregory, G. L.↗
NASA NTRS1977

Applicability of empirical data currently used in predicting solid propellant exhaust plumes

Theoretical and experimental approaches to exhaust plume analysis are compared. A two-phase model is extended to include treatment of reacting gas chemistry, and thermodynamical modeling of the gaseous phase of the flow field is considered. The applicability of empirical data currently available to define particle drag coefficients, heat transfer coefficients, mean particle size, and particle size distributions is investigated. Experimental and analytical comparisons are presented for subscale solid rocket motors operating at three altitudes with attention to pitot total pressure and stagnation point heating rate measurements. The mathematical treatment input requirements are explained. The two-phase flow field solution adequately predicts gasdynamic properties in the inviscid portion of two-phase exhaust plumes. It is found that prediction of exhaust plume gas pressures requires an adequate model of flow field dynamics.

Tevepaugh, J. A.↗
NASA NTRS1977

Semiclassical dynamics on multiple electronic surfaces - Three-dimensional treatment of reactive F + H2

The role of electron transitions in collisions is studied for the F + H2 reaction by combining quasi-classical Monte Carlo trajectories with a semiclassical decoupling approximation for the electron transitions. Attention is directed at the reaction of excited state F atoms reacting to form ground state products; the reactants are initiated in either of two spin-orbit states of the atom with the diatom in the ground vibrational state and the lowest four rotational states, at relative translational energies of 0.1, 0.2 and 0.3 eV. Even if the reactants are initiated on the excited state surface, the reactive cross sections (which are classically forbidden) are significant. The major dynamical effects of the excited state reaction are the flow of reactant electronic energy into product internal energy.

Komornicki, A.↗
NASA NTRS1977

Odd nitrogen in the mesosphere and thermosphere - Its chemistry and transport

The atomic nitrogen in the thermosphere, which is produced either in its ground term or in a highly reactive metastable term, reacts with molecular oxygen to form nitric oxide and atomic oxygen. However, nitric oxide is destroyed in reactions with atomic nitrogen in which molecular nitrogen and atomic oxygen is formed. Adopted reactions and rate coefficients for odd nitrogen chemistry are listed in a table. An analysis is conducted of the temperature distribution below 150 km and its effect on the odd nitrogen chemistry. The latitudinal distribution of nitric oxide is discussed. Satellite measurements have shown that nitric oxide concentrations at high latitudes are highly variable in both time and space. Their average concentrations are 3-4 times higher than at mid-latitudes. The measured variation of nitric oxide density as a function of latitude is shown in a graph.

Rusch, D. W.↗
NASA NTRS1978

Turbulent viscous shock layer solutions for Jovian entry at small angles of attack

The equations governing the laminar and turbulent flows of reacting gas mixtures in chemical equilibrium over axially symmetric blunt bodies at small angles of attack are developed and presented in the unsteady conservative form. Solutions are obtained in the planes of symmetry of the flow field for the typical conditions encountered by a probe entering the Jovian atmosphere at small angles of attack. The eddy-viscosity is approximated by a two-layer model. The shock wave is treated as a discontinuity across which the shock relations are used to compute the flow conditions behind the shock. A time-asymptotic finite-difference method is used to solve the equations. The zero angle of attack results for a hyperboloid are compared with the existing results but neither experimental nor computational results are available for comparison with the present results at angle of attack.

Jumar, A.↗
NASA NTRS1978

Candidate interstellar molecules formed from ion-molecule reactions of NO

Molecular orbital calculations using the MINDO/3 method were performed on a series of small molecules to explore reactions of NO which could lead to formation of interstellar molecules. Specifically, equilibrium geometries, isomeric energies, heats of reactions, and reaction pathways were calculated for plausible ion-molecule reactions involving NO and NO(+). The results of these calculations suggest that HNO(+) and HON(+) could be present in observable abundance in interstellar clouds. These species can be formed by the reaction of NO with H3(+) but not by NO(+) with H2. Moreover, they are stable to dissociation and do not react with H2 to re-form NO or to form isomers of HNOH(+).

Loew, G. H.↗
NASA NTRS1978

Artificially created holes in the ionosphere

The artificial creation of ionospheric holes by the release of highly reactive molecules into the F region is investigated. Through ion-atom interchange or charge transfer reactions, H2 or H2O reacts with O(+) to form OH(+) or H2O(+), respectively, which subsequently dissociatively recombines with electrons at a very rapid rate. The diffusion of H2 is also modified by chemical loss to the ambient atomic oxygen atmosphere. The limited spatial and temporal extent of the hole-making process allows several approximations to be made which permit three-dimensional analytic solutions of the continuity equations for the released particles, the O(+) and e(-) densities, and the intermediary molecular ions. A versatile formalism is developed whereby the hole-making capability of virtually any spatial-temporal configuration of released particles can be determined by convolving a set of destruction operators which can be viewed as Green's functions for the problem. As a specific application of the techniques developed, the modification of a winter nighttime ionosphere is described by simulating the release of 1000 kg of water vapor near a height of 300 km.

Mendillo, M.↗
NASA NTRS1978

Effects of small angle of attack on the radiating viscous shock layer solutions for Jovian entry

Results are presented for the laminar and turbulent flows of a reacting mixture of hydrogen-helium in chemical equilibrium over blunted cones of large half angles at small angles of attack. The freestream conditions correspond to a typical Jovian entry trajectory point. Radiative heat flux is calculated by using a realistic step-function model for the absorption coefficient. An investigation is also made to determine whether a blunted cone at small angles of attack can be replaced by equivalent bodies at zero angle of attack for the purpose of calculating the shock shapes, surface pressure, skin friction and heating rates.

Kumar, A.↗
NASA NTRS1977

Pyrolysis of organic compounds in the presence of ammonia The Viking Mars lander site alteration experiment

The influence of ammonia on the pyrolysis pattern of selected organic substances sorbed on an inorganic phase was investigated. The thermal degradation products were identified by gas chromatography-mass spectrometry. The feasibility of this technique was tested on a meteoritic sample. All substances examined react with ammonia at the pyrolysis temperature of 500 C, the major products being nitriles and heterocyclic compounds in which nitrogen was incorporated. Based on these results, a model for the non-equilibrium production of organic compounds on Jupiter is discussed. The investigation was performed in connection with the Viking lander molecular analysis. The results obtained indicate that the concentrations of ammonia in the retrorocket fuel exhaust would have been probably too small to produce significant changes in the Martian soil organic compounds if any were found.

Holzer, G.↗
NASA NTRS1978

Measurement of tropospheric 300 nm solar ultraviolet flux for determination of O/1D/ photoproduction rate

The tropospheric importance of the OH radical, and the reaction scheme that leads to its formation, are now being widely investigated. Ozone photolysis at wavelengths no greater than 318 nm produces O(1D), a small fraction of which then reacts with water vapor to yield OH. Although experimental data are available for the O(1D) quantum yield, as well as the O3 absorption cross section, all previous tropospheric photochemical models have had to use theoretical calculations to determine the UV flux. Discussed in this paper are aircraft spectral measurements of the solar UV flux at two altitudes - 2 and 6 km. These results have been compared with three theoretical approaches. The measured experimental fluxes have been combined here with recent quantum yield data to calculate the O(1D) photoproduction rate for various albedo values. This rate is larger than that used in models by about a factor of 2 for reasonable values of assumed albedo.

Sellers, B.↗
NASA NTRS1975

Agglutinates as indicators of lunar soil maturity - The rare gas evidence at Apollo 16

The weight percent of lunar agglutinic glass (glass-welded aggregates resulting from micrometeorite impacts) in Apollo 16 bulk soils is considered with respect to quantities of trapped rare gases, e.g., He-4, Ne-20, Ar-36, Kr-84, and Xe-132, in an effort to determine the cumulative time a given soil sample has spent exposed on the lunar surface. The agglutinic glass, which reacts strongly in a magnetic field, is obtained by the standard fluid (methanol)-magnetic technique. It is noted that the absolute concentrations of trapped rare gases all show a linear relationship with increasing agglutinic glass content.

Charette, M. P.↗
NASA NTRS1978

Implications of the hypohydrous history of Mars

The extent to which fluvial processes occurred in Mars is considered with reference to the oxidation of soil organics by the gamma-Fe2O3/H2O2 system. Data from the Viking biology experiments suggest that the acidity of gamma-Fe2O3 controls the ionization of hydrogen peroxide - that is, in acid conditions and in the presence of large concentrations of formate, gamma-Fe2O3 reacts efficiently with peroxide to oxidize formate to CO2 and H2O. Fe3O4, alpha-Fe2O3, and calcite are basic and block the oxidation of formate. The properties of this system are consistent with the hypothesis that Mars has been under a severe regime of dryness.

Oyama, V. I.↗
NASA NTRS1977

Thermochemical water decomposition

At present, nearly all of the hydrogen consumed in the world is produced by reacting hydrocarbons with water. As the supply of hydrocarbons diminishes, the problem of producing hydrogen from water alone will become increasingly important. Furthermore, producing hydrogen from water is a means of energy conversion by which thermal energy from a primary source, such as solar or nuclear fusion of fission, can be changed into an easily transportable and ecologically acceptable fuel. The attraction of thermochemical processes is that they offer the potential for converting thermal energy to hydrogen more efficiently than by water electrolysis. A thermochemical hydrogen-production process is one which requires only water as material input and mainly thermal energy, or heat, as an energy input. Attention is given to a definition of process thermal efficiency, the thermodynamics of the overall process, the single-stage process, the two-stage process, multistage processes, the work of separation and a process evaluation.

Funk, J. E.↗
NASA NTRS1978

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster decelerator subsystem drop test vehicle. Volume 3: Pylon load data method 1

The pylon loading at the drop test vehicle and wing interface attach points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the foreward hook guide to be one-fourth of the fore and aft stiffness of each drag pin. The net effect of this assumption is that the forward hook guide reacts approximately 85% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

Quade, D. A.↗
NASA NTRS1978

Load and dynamic assessment of B-52B-008 carrier aircraft for finned configuration 1 space shuttle solid rocket booster deceleration subsystem drop test vehicle. Volume 4: Pylon load data

The pylon loading at the drop test vehicle and wing interface attack points is presented. The loads shown are determined using a stiffness method, which assumes the side stiffness of the forward hook guide and the fore and aft stiffness of each drag pin to be equal. The net effect of this assumption is that the forward hook guide reacts approximately 96% of the drop test vehicle yawing moment. For a comparison of these loads to previous X-15 analysis design loadings, see Volume 1 of this document.

Quade, D. A.↗
NASA NTRS1978

Process for the preparation of calcium superoxide

Calcium superoxide is prepared in high yields by spreading a quantity of calcium peroxide diperoxyhydrate on the surface of a container, positioning said container in a vacuum chamber on a support structure through which a coolant fluid can be circulated, partially evacuating said vacuum chamber, allowing the temperature of the diperoxyhydrate to reach the range of about 0 to about 40 C; maintaining the temperature selected for a period of time sufficient to complete the disproproriation of the diperoxyhydrate to calcium superoxide, calcium hydroxide, oxygen, and water; constantly and systematically removing the water as it is formed by sweeping the reacting material with a current of dry inert gas and/or by condensation of said water on a cold surface; backfilling the chamber with a dry inert gas; and finally, recovering the calcium superoxide produced.

Ballou, E. V.↗
NASA NTRS1978

The development of a three-dimensional partially elliptic flow computer program for combustor research

A three dimensional, partially elliptic, computer program was developed. Without requiring three dimensional computer storage locations for all flow variables, the partially elliptic program is capable of predicting three dimensional combustor flow fields with large downstream effects. The program requires only slight increase of computer storage over the parabolic flow program from which it was developed. A finite difference formulation for a three dimensional, fully elliptic, turbulent, reacting, flow field was derived. Because of the negligible diffusion effects in the main flow direction in a supersonic combustor, the set of finite-difference equations can be reduced to a partially elliptic form. Only the pressure field was governed by an elliptic equation and requires three dimensional storage; all other dependent variables are governed by parabolic equations. A numerical procedure which combines a marching integration scheme with an iterative scheme for solving the elliptic pressure was adopted.

Pan, Y. S.↗
NASA NTRS1978

Directional errors of movements and their correction in a discrete tracking task

Subjects can correct their own errors of movement more quickly than they can react to external stimuli by using three general categories of feedback: (1) knowledge of results, primarily visually mediated; (2) proprioceptive or kinaesthetic such as from muscle spindles and joint receptors, and (3) corollary discharge or efference copy within the central nervous system. The effects of these feedbacks on simple reaction time, choice reaction time, and error correction time were studied in four normal human subjects. The movement used was plantarflexion and dorsiflexion of the ankle joint. The feedback loops were modified, by changing the sign of the visual display to alter the subject's perception of results, and by applying vibration at 100 Hz simultaneously to both the agonist and antagonist muscles of the ankle joint. The central processing was interfered with when the subjects were given moderate doses of alcohol (blood alcohol concentration levels of up to 0.07%). Vibration and alcohol increase both the simple and choice reaction times but not the error correction time.

Jaeger, R. J.↗