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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Inadvertent weather modification by Chicago-northern Indiana pollution sources observed by ERTS-1

Discussion of an apparent case of cloud modification by the effluents from numerous industrial sites in the Chicago-Gary complex. An analysis is made of a series of ERTS-1 images taken over Lake Michigan on Nov. 24, 1972, which apparently show modification of 1.5-km-wide cumulus cloud streets by the effluents of the industries at the southern end of the lake. A close inspection of these images reveals numerous interesting phenomena, the most important of which is the apparent alteration of the cumulus clouds along the axis of the major pollution plumes.

Lyons, W. A.↗
NASA NTRS1975

NASTRAN modifications for recovering strains and curvatures

Modifications to the NASTRAN structural analysis computer program are described. The modifications allow the recovery of strain and curvature data for the general two-dimensional elements, in addition to the usual stress data. Option features allow the transformation of the strain/curvature (or stress) data to a common coordinate system and representation at the grid points of the structural model rather than at the conventional element center locations. Usage information is provided which will allow present users of NASTRAN to easily utilize the new capability.

Hennrich, C. W.↗
NASA NTRS1976

Modifications of the law of the wall and algebraic turbulence modelling for separated boundary layers

Various modifications of the conventional algebraic eddy viscosity turbulence model are investigated for application to separated flows. Friction velocity is defined in a way that avoids singular behavior at separation and reattachment but reverts to the conventional definition for flows with small pressure gradients. This leads to a modified law of the wall for separated flows. The effect on the calculated flow field of changes in the model that affect the eddy viscosity at various distances from the wall are determined by (1) switching from Prandtl's form to an inner layer formula due to Clauser at various distances from the wall, (2) varying the constant in the Van Driest damping factor, (3) using Clauser's inner layer formula all the way to the wall, and (4) applying a relaxation procedure in the evaluation of the constant in Clauser's inner layer formula. Numerical solutions of the compressible Navier-Stokes equations are used to determine the effects of the modifications. Experimental results from shock-induced separated flows at Mach numbers 2.93 and 8.45 are used for comparison. For these cases improved predictions of wall pressure distribution and positions of separation and reattachment are obtained from the relaxation version of the Clauser inner layer eddy viscosity formula.

Baldwin, B. S.↗
NASA NTRS1976

Quaternary and quinary modifications of the eutectic superalloy gamma/gamma prime-delta

Quaternary modifications and quinary additions from the elements Co, Ti, Mo, W, Re, B, Si, and Ta to the baseline quaternary alloy gamma/gamma prime-delta Ni-19.7 at.% Nb-6.0 at.% Cr-2.5 at.% Al are examined for various concentrations. From modification studies five alloys were chosen for detailed mechanical property characterization: Ni-19.7 Nb-6.0 Cr-2.5 Al-1.0 W; Ni-19.7 Nb-6.0 Cr-2.5 Al-1.0 Mo; Ni-18.6 Nb-6.0 Cr-2.5 Al-0.87 Ti; Ni-20.2 Nb-6.0 Cr-2.5 Al-2.0 Co; and Ni-17.9 Nb-6.0 Cr-2.5 Al-3.0 Ta. It is shown that extensive alloying of the baseline quaternary alloy is possible for elements exhibiting a wide solubility range in both phases, and that limited substitution of W, Mo, Re, Si, and B is possible for elements with restricted solid solubility especially in the delta phase. Improvement of creep rupture strength and cyclic oxidation resistance at 1100 C is discussed.

Lemkey, F. D.↗
NASA NTRS1976

Space shuttle orbiter trimmed center-of-gravity extension study: Volume 2: Effects of configuration modifications on the aerodynamic characteristics of the 140 A/B orbiter at transonic speeds

Tests were conducted in the LaRC 8-foot transonic pressure tunnel to determine effects of fuselage nose and wing fillet modifications on the transonic aerodynamic characteristics of a space shuttle orbiter configuration. In addition to reshaping the baseline wing planform fillet, small canards were added to the configuration. The modifications considered were of interest in extending the forward center-of-gravity boundary for the configuration.

Phillips, W. P.↗
NASA NTRS1976

Position paper on the potential of inadvertent weather modification of the Florida peninsula resulting from the stabilized ground cloud

Based on the climatology of the Florida Peninsula, we assessed the risk for weather modification. Certain weather situations warrant launch rescheduling because of the risk of possible impact on hurricanes, hail formation and lightning activity, strong wind developments, and intensification of high rainfall rates. The cumulative effects of 40 launches per year on weather modification were found to be insignificant.

Bollay, E.↗
NASA NTRS1978

Space Shuttle Orbiter trimmed center-of-gravity extension study. Volume 4: Effects of configuration modifications on the aerodynamic characteristics of the 139B orbiter at Mach 20.3

Force tests were conducted at Mach 20.3 to determine the effect of several forebody, wing-fillet, and canard modifications on the hypersonic trim capability of a 139B Space Shuttle Orbiter model. Force and moment data were obtained at angles of attack of 10 deg to 54 deg at zero sideslip angle and at a Reynolds number of 1,900,000 based on body length. The results indicated that wing-fillet and canard modifications would increase the allowable forward trimmed center-of-gravity capability by as much as 3.0 percent of the body length.

Scallion, W. I.↗
NASA NTRS1978

Studies of satellite support to weather modification in the western US region

The applications of meteorological satellite data to both summer and winter weather modification programs are addressed. Appraisals of the capability of satellites to assess seedability, to provide real-time operational support, and to assist in the post-experiment analysis of a seeding experiment led to the incorporation of satellite observing systems as a major component in the Bureau of Reclamations weather modification activities. Satellite observations are an integral part of the South Park Area cumulus experiment (SPACE) which aims to formulate a quantitative hypothesis for enhancing precipitation from orographically induced summertime mesoscale convective systems (orogenic mesoscale systems). Progress is reported in using satellite observations to assist in classifying the important mesoscale systems, and in defining their frequency and coverage, and potential area of effect. Satellite studies of severe storms are also covered.

Cotton, W. R.↗
NASA NTRS1978

Meteorological satellites in support of weather modification

During the past several years, many weather modification programs have been incorporating meteorological satellite data into both the operations and the analysis phase of these projects. This has occurred because of the advancement of the satellite as a mesoscale measurement platform, both temporally and spatially, and as the availability of high quality data has increased. This paper surveys the applications of meteorological satellite data to both summer and winter weather modification programs. A description of the types of observations needed by the programs is given, and an assessment of how accurately satellites can determine these necessary parameters is made.

Reynolds, D. W.↗
NASA NTRS1974

Evaluation of exercise-respiratory system modifications and preliminary respiratory-circulatory system integration scheme

The respiratory control system, functioning as an independent system, is presented with modifications of the exercise subroutine. These modifications illustrate an improved control of ventilation rates and arterial and compartmental gas tensions. A very elementary approach to describing the interactions of the respiratory and circulatory system is presented.

Gallagher, R. R.↗
NASA NTRS1979

Upper-surface modifications for C sub l max improvement of selected NASA 6-series airfoils

The thickness of the upper surface of 64 airfoils was increased from the leading edge to the position of maximum thickness. The modifications were generated using a numerical optimization routine coupled with an aerodynamic analysis code. The type of modification presented can be used for aircraft design or for the retrofit of current aircraft to improve the stall characteristics and climb performance. The coordinates of the modified airfoils are presented with plots of the forward 45% of the profiles and pressure distributions for both the modified and unmodified sections at an angle of attack of 14 degrees.

Szelazek, C. A.↗
NASA NTRS1979

The role of rim slumping in the modification of lunar impact craters

The role of rim slumping in the formation of terraces on interior crater walls and consequent modifications of the shapes of large lunar impact craters is evaluated. Impact excavation cavities were reconstructed by means of a terrace restoration model for twelve lunar craters ranging in diameter from 19 to 137 km. For craters up to 30 km, reconstructed cavity depths are comparable to or greater than cavity depths extrapolated from nonterraced smaller craters, and in the 30 to 70 km diameter range, the reconstructed cavity depths are significantly greater. For craters larger than 70 km, however, the reconstructed cavity depths are consistently less than those predicted from small crater morphometry, indicating a significant additional contribution from ejecta fallback and basement rebound to the modification of the shape of impact craters greater than 70 km.

Settle, M.↗
NASA NTRS1979

Effect of several airframe/nozzle modifications on the drag of a variable-sweep bomber configuration

A variable sweep bomber aircraft model was investigated to identify modifications for drag reduction. Modifications included simulated two dimensional nozzles, staggered and extended nozzles; short, long, and no interfairings between the nozzles; partial and complete wing-glove fairings; glove-fuselage sidefairing; fuselage underfairing; and wing pods. The variable wing sweep and variable exhaust nozzles of the scale model are discussed.

Re, R. J.↗
NASA NTRS1979

Position paper on the potential of inadvertent weather modification of the Florida Peninsula resulting from neutralization of space shuttle solid rocket booster exhaust clouds

A concept of injecting compounds into the exhaust cloud was proposed to neutralize the acidic nature of the low-level stabilized ground cloud (SGC) was studied. The potential Inadvertent Weather Modification caused by exhaust cloud characteristics from three hours to seven days after launch was studied. Possible effects of the neutralized SGC in warm and cloud precipitation processes were discussed. Based on a detailed climatology of the Florida Peninsula, the risk for weather modification under a variety of weather situations was assessed.

Bollay, E.↗
NASA NTRS1979

Exploratory study of the effects of wing-leading-edge modifications on the stall/spin behavior of a light general aviation airplane

Configurations with full-span and segmented leading-edge flaps and full-span and segmented leading-edge droop were tested. Studies were conducted with wind-tunnel models, with an outdoor radio-controlled model, and with a full-scale airplane. Results show that wing-leading-edge modifications can produce large effects on stall/spin characteristics, particularly on spin resistance. One outboard wing-leading-edge modification tested significantly improved lateral stability at stall, spin resistance, and developed spin characteristics.

Source record↗
NASA NTRS1980

The effects of leading edge modifications on the post-stall characteristics of wings

An investigation of the effects of leading edge modifications on the post-stall characteristics of two rectangular planform wings in a series of low speed wind tunnel tests is presented. Abrupt discontinuities in the leading edge shape of the wings were produced by placing a nose glove over a portion of the span or by deflecting sections of a segmented leading edge flap. Six component balance data, oil flow visualization photographs, and pressure distribution measurements were obtained, and tests made to study the development of flow separation at stall on small scale planform wing models. Results of oil flow visualization tests at and beyond stall showed the formation of counter-rotating swirl patterns on the upper surface of the '2-D' and '3-D' wings, and results of a numerical lifting line technique applied to wings with leading edge modifications are included.

Winkelmann, A. E.↗
NASA NTRS1980

Comments on 'Some realistic modifications of simple climate models'

Lindzen and Farrell (LF) in 1977 argued that the eddy diffusion is not a good parameterization of meridional heat flux in tropical latitudes and that model sensitivity could be altered drastically if a more 'realistic' (nondiffusive) parameterization of tropical transports were included. LF suggested modifications to the heat transport term in Budyko's (1969) zonal energy-balance climate model. The authors do not believe that the modifications suggested by LF are necessarily more realistic than the original formulation, and thus it is not believed that the quantitative results offered by LF can be demonstrated as more realistic than those they replace. Reasons for the belief are discussed.

Warren, S. G.↗