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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Effect of geometrical and flow parameters on high-effectiveness region of film cooling

Previous analyses for an inviscid jet injected into a stream and the turbulent mixing region which forms between jet and stream are used to find the extent of the core region in a cooling film by calculating the growth of the turbulent boundary layer on the downstream wall. The core is a region of nearly perfect effectiveness which ends at the intersection of the boundary layer and the mixing region. The calculations show that the most important geometrical factor bearing on the length of the core is the curvature of the wall. When the radius of curvature is large, the boundary layer remains thin and the core is long. The effects of Reynolds number, total-pressure difference between film and stream, and lateral position of the downstream wall are also investigated. The step configuration is shown to have a longer core than the slot for the same flow conditions.

Braum, W. H.↗
NASA NTRS1980

D- and E-Region effects

A time dependent analytic formalism is utilized to examine the competing effects of transport, photodissociation, and frequency of injection on the steady state global distribution of heavy lift launch vehicle (HLLV) second stage discharges of H2O. The model is employed to estimate concomitant effects on the ion chemistries of the D and E regions of the atmosphere.

Forbes, J. M.↗
NASA NTRS1991

Ozone budget over the Amazon - Regional effects from biomass-burning emissions

Data from the NASA dry-season Amazon boundary layer experiment (ABLE2A) is used with a 1D tropospheric photochemical model to analyze the atmospheric chemistry in the region and determine the impact of the long-range transport of biomass-burning emissions. Inputs of surface sources and the deposition of various species measured during ABLE2A are employed to simulate the background atmosphere, and haze characteristics are introduced for a 12-hr simulation. The in situ ozone production rate doubles during the period of haze when hydrocarbons are present. The model predicts that the production of ozone is enhanced during the dry season, and that increased ozone during the southern tropical burning season is related to the regional transport of haze.

Richardson, Jennifer L.↗
NASA NTRS1978

E region coupling effects on the Perkins spread F instability

The Perkins instability theory for mid-latitude spread F is generalized to include the effects of the E region on growth rates. A three-layer model, representing the E region, the F region, and a resistive layer of low Pedersen conductivity which separates them, is developed. The E region Pedersen current has a stabilizing effect on the perturbed F region, thereby reducing the growth rate of the instability. For spread F onset on September 17, 1974, the maximum growth rate is found to be only one third of the Perkins growth rate. The resistive layer reduces the electric field perturbation in the E region for short wavelengths but has little effect for long wavelengths.

Klevans, E. H.↗
NASA NTRS1992

Regional climatic effects of atmospheric SO2 on Mars

The conditions under which the valley networks on Mars may have formed remains controversial. The magnitude of an atmospheric greenhouse effect by an early massive CO2 atmosphere has recently been questioned by Kasting. Recent calculations indicate that if solar luminosity were less than about 86 percent of its current value, formation of CO2 clouds in the Martian atmosphere would depress the atmospheric lapse rate and reduce the magnitude of surface warming. In light of recent revisions of magma generation on Mars during each Martian epoch, and the suggestions by Wanke et al. that the role of liquid SO2 should be more carefully explored, we have recalculated the potential greenhouse warming by atmospheric SO2 on Mars, with an emphasis on more localized effects. In the vicinity of an active eruption, the concentration of atmospheric SO2 will be higher than if it is assumed that the erupted SO2 is instantaneously globally distributed. The local steady-state concentration of SO2 is a function of the rate at which it is released, its atmospheric lifetime, and the rate at which local winds act to disperse the SO2. We have made estimates of eruption rates, length of eruption, and dispersion rates of volcanically released SO2, for a variety of atmospheric conditions and atmospheric lifetimes of SO2 to explore the maximum regional climatic effect of SO2.

Postawko, S. E.↗
NASA NTRS1991

Energy balance in the solar transition region. II - Effects of pressure and energy input on hydrostatic models

The radiation of energy by hydrogen lines and continua in hydrostatic energy-balance models of the transition region between the solar chromosphere and corona is studied using models which assume that mechanical or magnetic energy is dissipated in the hot corona and is then transported toward the chromosphere down the steep temperature gradient of the transition region. These models explain the average quiet sun and also the entire range of variability of the Ly-alpha lines. The relations between the downward energy flux, the pressure of the transition region, and the different hydrogen emission are described.

Fontenla, J. M.↗
NASA NTRS1979

Effects of regional hemoconcentration during LBNP on plasma volume determinations

Blood samples were obtained from forearm vein or artery with indwelling cannula (1) before, (2) during the last min, and (3) about 2 min after lower body negative pressure (LBNP) in 16 experiments to determine whether plasma volume (PV) estimates were affected by regional hemoconcentration in the lower body. Total hemoglobin (THb) was estimated with the CO method prior to LBNP. Hemoglobin (Hb) and hematocrit (Hct) values from (2) gave only a 3% (87 ml) loss in PV due to LBNP, assuming no change in THb. However, Hb and Hct values from (3) showed an 11% loss in PV (313 ml). This 72% underestimation of PV loss with (2) must have resulted from the sequestration of blood and subsequent hemoconcentration in the lower body during LBNP. The effects of LBNP on PV should be estimated 1-3 min after exposure, after mixing but before extravascular fluid returns to the circulation.

Loeppky, J. A.↗
NASA NTRS1995

Observations of the Global Characteristics and Regional Radiative Effects of Marine Cloud Liquid Water

The large-scale spatial distribution and temporal variability of cloud liquid water path (LWP) over the world's oceans and the relationship of cloud LWP to temperature and the radiation budget are investigated using recent satellite measurements from the Special Sensor Microwave/Imager (SSM/I), the Earth Radiation Budget Experiment (ERBE), and the International Satellite Cloud Climatology Project (ISCCP). Observations of cloud liquid water on a 2.5 deg x 2.5 deg and are used over a 53-month period beginning July 1987 and ending in December 1991. The highest values of cloud liquid water (greater than 0.13 kg/sq m) occur largely along principal routes of northern midlatitude storms and in areas dominated by tropical convection. The zonally averaged structure is distinctly trimodal, where maxima appear in the midlatitudes and near the equator. The average marine cloud LWP over the globe is estimated to be about 0.113 kg/sq m. Its highest seasonal variability is typically between 15% and 25% of the annual mean but in certain locations can exceed 30%. Comparisons of cloud LWP to temperature for low clouds during JJA and DJF of 1990 show significant positive correlations at colder temperatures and negative correlations at warmer temperatures. The correlations also exhibit strong seasonal and regional variation. Coincident and collocated observations of cloud LWP from the SSM/I and albedo measurements from the Earth Radiation Budget Satellite (ERBS) and the NOAA-10 satellite are compared for low clouds in the North Pacific and North Atlantic. The observed albedo-LWP relationships correspond reasonably well with theory, where the average cloud effective radius (r(sub e)) is 11.1 microns and the standard deviation is 5.2 microns. The large variability in the inferred values of r(sub e) suggests that other factors may be important in the albedo-LWP relationships. In terms of the effect of the LWP on the net cloud forcing, the authors find that a 0.05 kg/sq m increase in LWP (for LWP less than 0.2 kg/sq m) results in a -25 W/sq m change in the net cloud forcing at a solar zenith angle of 75 deg.

Greenwald, Thomas J.↗
NASA NTRS1980

The effects of regional insolation differences upon advanced solar thermal electric power plant performance and energy costs

The performance and cost of four 10 MWe advanced solar thermal electric power plants sited in various regions of the continental United States was studied. Each region has different insolation characteristics which result in varying collector field areas, plant performance, capital costs and energy costs. The regional variation in solar plant performance was assessed in relation to the expected rise in the future cost of residential and commercial electricity supplied by conventional utility power systems in the same regions. A discussion of the regional insolation data base is presented along with a description of the solar systems performance and costs. A range for the forecast cost of conventional electricity by region and nationally over the next several decades is given.

Latta, A. F.↗