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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Fast-response atmospheric-pollutant monitor

Fast infrared spectrometer measures atmospheric C0, CH4, and HC1 over range of 1 to 12 ppm. With modifications it could measure other pollutants and use natural light as source. Cell filled with sample to be measured filters out spectral lines of interest. Infrared beam passes through rotating cell holder that produces chopped signals at two frequencies. Difference in signal amplitudes depends on amount of test gas in sample. Signal processing circuitry amplifies and separates test-gas and reference signals.

Sebacher, D. I.↗
NASA NTRS1981

Simultaneous measurement of three atmospheric pollutants

Method enables simultaneous concentration monitoring of atmospheric SO2, NO, and NO2. Fluorescing pollutant gases in sample are excited by visible output of dye laser and its second-harmonic ultraviolet frequencies. Three photomultipliers, each with suitable optical filters, view fluorescence. Method tests ambient air, stack emissions, and highway automotive exhausts.

Sinha, M. P.↗
NASA NTRS1979

Advanced catalytic combustors for low pollutant emissions, phase 1

The feasibility of employing the known attractive and distinguishing features of catalytic combustion technology to reduce nitric oxide emissions from gas turbine engines during subsonic, stratospheric cruise operation was investigated. Six conceptual combustor designs employing catalytic combustion were defined and evaluated for their potential to meet specific emissions and performance goals. Based on these evaluations, two parallel-staged, fixed-geometry designs were identified as the most promising concepts. Additional design studies were conducted to produce detailed preliminary designs of these two combustors. Results indicate that cruise nitric oxide emissions can be reduced by an order of magnitude relative to current technology levels by the use of catalytic combustion. Also, these combustors have the potential for operating over the EPA landing-takeoff cycle and at cruise with a low pressure drop, high combustion efficiency and with a very low overall level of emission pollutants. The use of catalytic combustion, however, requires advanced technology generation in order to obtain the time-temperature catalytic reactor performance and durability required for practical aircraft engine combustors.

Dodds, W. J.↗
NASA NTRS1980

Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities

The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented.

Levine, J. S.↗
NASA NTRS1980

Pollutant emissions from flat-flame burners at high pressures

Maximum flame temperatures and pollutant emission measurements for NOx, CO, and UHC (unburned hydrocarbons) are reported for premixed methane air flat flames at constant total mass flow rate over the pressure range from 1.9 to 30 atm and for equivalence ratios from 0.84 to 1.12. For any given pressure, maxima typically occur in both the temperature and NOx emissions curves slightly to the lean side of stoichiometric conditions. The UHC emissions show minima at roughly the same equivalence ratios. The CO emissions, however, increase continually with increasing equivalence ratio. Flame temperature and NOx emissions decrease with increasing pressure, while the opposite is true for the CO and UHC emissions. The NOx data correlate reasonably well as a function of flame temperature only. Four flameholders, differing only slightly, were used. In general, the temperature and emissions data from these four flameholders are similar, but some differences also exist. These differences appear to be related to minor variations in the condition of the flameholder surfaces.

Maahs, H. G.↗
NASA NTRS1980

Assessment of the use of space technology in the monitoring of oil spills and ocean pollution: Technical volume. Executive summary

The potential of space systems and technology for detecting and monitoring ocean oil spills and waste pollution was assessed as well as the impact of this application on communication and data handling systems. Agencies charged with responsibilities in this area were identified and their measurement requirements were ascertained in order to determine the spatial resolution needed to characterize operational and accidental discharges. Microwave and optical sensors and sensing techniques were evaluated as candidate system elements. Capabilities are described for the following: synthetic aperture radar, microwave scatterometer, passive microwave radiometer, microwave altimeter, electro-optical sensors currently used in airborne detection, existing space-based optical sensors, the thematic mapper, and the pointable optical linear array.

Alvarado, U. R.↗
NASA NTRS1978

Three dimensional thermal pollution models. Volume 1: Review of mathematical formulations

A mathematical model package for thermal pollution analyses and prediction is presented. These models, intended as user's manuals, are three dimensional and time dependent using the primitive equation approach. Although they have sufficient generality for application at sites with diverse topographical features; they also present specific instructions regarding data preparation for program execution and sample problems. The mathematical formulation of these models is presented including assumptions, approximations, governing equations, boundary and initial conditions, numerical method of solution, and same results.

Lee, S. S.↗
NASA NTRS1980

Meteorological and air pollution modeling for an urban airport

Results are presented of numerical experiments modeling meteorology, multiple pollutant sources, and nonlinear photochemical reactions for the case of an airport in a large urban area with complex terrain. A planetary boundary-layer model which predicts the mixing depth and generates wind, moisture, and temperature fields was used; it utilizes only surface and synoptic boundary conditions as input data. A version of the Hecht-Seinfeld-Dodge chemical kinetics model is integrated with a new, rapid numerical technique; both the San Francisco Bay Area Air Quality Management District source inventory and the San Jose Airport aircraft inventory are utilized. The air quality model results are presented in contour plots; the combined results illustrate that the highly nonlinear interactions which are present require that the chemistry and meteorology be considered simultaneously to make a valid assessment of the effects of individual sources on regional air quality.

Swan, P. R.↗
NASA NTRS1982

Two-Stage Combustor Reduces Pollutant Emissions

By controlling fuel-to-air ratio of local reactants, pollutant emissions would be minimized in a proposed two-stage combustor for gas-turbine engines. It would use fuel-rich partial-oxidation stage and air-rich combustion stage to reduce emissions of nitrogen oxide, carbon monoxide and hydrocarbons. Combustor fuel-lean burning limit would be extended simultaneously.

Clayton, R. M.↗
NASA NTRS1981

Some aspects of analytical chemistry as applied to water quality assurance techniques for reclaimed water: The potential use of X-ray fluorescence spectrometry for automated on-line fast real-time simultaneous multi-component analysis of inorganic pollutants in reclaimed water

The potential use of isotopically excited energy dispersive X-ray fluorescence (XRF) spectrometry for automated on line fast real time (5 to 15 minutes) simultaneous multicomponent (up to 20) trace (1 to 10 parts per billion) analysis of inorganic pollutants in reclaimed water was examined. Three anionic elements (chromium 6, arsenic and selenium) were studied. The inherent lack of sensitivity of XRF spectrometry for these elements mandates use of a preconcentration technique and various methods were examined, including: several direct and indirect evaporation methods; ion exchange membranes; selective and nonselective precipitation; and complexation processes. It is shown tha XRF spectrometry itself is well suited for automated on line quality assurance, and can provide a nondestructive (and thus sample storage and repeat analysis capabilities) and particularly convenient analytical method. Further, the use of an isotopically excited energy dispersive unit (50 mCi Cd-109 source) coupled with a suitable preconcentration process can provide sufficient sensitivity to achieve the current mandated minimum levels of detection without the need for high power X-ray generating tubes.

Ling, A. C.↗
NASA NTRS1981

Pollution reduction technology program small jet aircraft engines, phase 3

A series of Model TFE731-2 engine tests were conducted with the Concept 2 variable geometry airblast fuel injector combustion system installed. The engine was tested to: (1) establish the emission levels over the selected points which comprise the Environmental Protection Agency Landing-Takeoff Cycle; (2) determine engine performance with the combustion system; and (3) evaulate the engine acceleration/deceleration characteristics. The hydrocarbon (HC), carbon monoxide (CO), and smoke goals were met. Oxides of nitrogen (NOx) were above the goal for the same configuration that met the other pollutant goals. The engine and combustor performance, as well as acceleration/deceleration characteristics, were acceptable. The Concept 3 staged combustor system was refined from earlier phase development and subjected to further rig refinement testing. The concept met all of the emissions goals.

Bruce, T. W.↗
NASA NTRS1982

Detection of regional air pollution episodes utilizing satellite digital data in the visual range

Digital analyses of satellite visible data for selected high-sulfate cases over the northeastern U.S., on July 21 and 22, 1978, are compared with ground-based measurements. Quantitative information on total aerosol loading derived from the satellite digitized data using an atmospheric radiative transfer model is found to agree with the ground measurements, and it is shown that the extent and transport of the haze pattern may be monitored from the satellite data over the period of maximum intensity for the episode. Attention is drawn to the potential benefits of satellite monitoring of pollution episodes demonstrated by the model.

Burke, H.-H. K.↗
NASA NTRS1982

A study of persistent elevated pollution episodes in the northeastern United States

To examine chemical transformation within stagnant air masses and the atmospheric processes acting upon such air masses, the United States EPA sponsored a study in the summer of 1980 in the northeastern region of the country. Ten research aircraft and several mobile and stationary surface monitoring platforms participated in an intensive measurement program between 16 July and 15 August 1980. Pollutants of interest included SO2, NO, NO(x), HC, O3, sulfate, nitrate, and aerosols in general. This paper summarizes the activities of these research aircraft. Three aircraft and one helicopter logged a total of 353 flight hours during 100 missions in the program. The flight patterns and data collected for each mission are documented. This summary will allow scientists who are interested in this data base to identify subsets of the data for model development.

Vaughan, W. M.↗
NASA NTRS1981

Detection of regional air pollution episodes utilizing satellite data in the visual range

A comparative analysis of satellite-observed haze patterns and ground-based aerosol measurements is carried out for July 20-23, 1978. During this period, a significant regional air pollution episode existed across the northeastern United States, accompanied by widespread haze, reduced surface visibility, and elevated sulfate levels measured by the Sulfate Regional Experiment (SURE) network. The results show that the satellite-observed haze patterns correlate closely with the area of reported low surface visibility (less than 4 mi) and high sulfate levels. Quantitative information on total aerosol loading derived from the satellite-digitized data, using an atmospheric radiative transfer model, agrees well with the results obtained from the ground-based measurements.

Bowley, C. J.↗
NASA NTRS1983

A survey of laser and selected optical systems for remote measurement of pollutant gas concentrations

Applications of the Differential Absorption Lidar (DIAL) technique to the remote sensing of pollutant gases are surveyed. In the DIAl technique, the differential absorption of two laser beams reflected back to a receiver from a target determines the concentration of the gas being studied. The types of instruments available are considered in detail: dye lidar (to measure nitrogen dioxide, sulfur dioxide, and ozone); carbon dioxide laser (for ozone, ethylene, ammonia, and hydrazine), helium-neon laser (for methane); hydrogen fluoride laser (for HF); and tunable diode laser (for nitric oxide and carbon monoxide). DIAL instruments are compared with other optical remote sensors such as Fourier-transform infrared spectrometers, correlation spectrometers (COSPEC and GASPEC), and grating spectrometers; and criteria for the selection of an appropriate gas measuring system are suggested. Laser and other optical remote sensors are found to be cost effective in many cases, despite the fact that they are more costly than point-monitoring systems.

Grant, W. B.↗
NASA NTRS1985

Laser Pollutant-Measuring Systems

Laser optical system for remote gas pollutant measurements surveyed. Laser systems discussed in published report, and choices of appropriate gasmeasuring instruments and their sensitivities evaluated.

Grant, W. B.↗
NASA NTRS1984

Definitions of noise and noise pollution

The definitions of noise and noise pollution are examined with emphasis on the psychological, physiological, sociological and economic impacts on personnel and the environment.

Source record↗
NASA NTRS1983

Light extinction by aerosols during summer air pollution

In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes, the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band lambda 440-870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99 percent of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 micron. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend on several aerosol parameters, but it is difficult to identify the dominant one. The effects of relative humidity and accumulation mode concentration on the optical thickness are analyzed theoretically, and compared with the measurements.

Kaufman, Y. J.↗