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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Nonequilibrium chemistry boundary layer integral matrix procedure

The development of an analytic procedure for the calculation of nonequilibrium boundary layer flows over surfaces of arbitrary catalycities is described. An existing equilibrium boundary layer integral matrix code was extended to include nonequilibrium chemistry while retaining all of the general boundary condition features built into the original code. For particular application to the pitch-plane of shuttle type vehicles, an approximate procedure was developed to estimate the nonequilibrium and nonisentropic state at the edge of the boundary layer.

Tong, H.↗
NASA NTRS1973

An automated procedure for computing flutter eigenvalues.

A new, fast and economical automated procedure for implementing the traditional V-g method of flutter solution is described. The procedure requires as input the generalized aerodynamic forces for a range of reduced frequencies obtained from an aerodynamic program. These aerodynamic forces are interpolated with respect to reduced frequency using a newly developed, partially tabulated cubic spline that is both fast in execution and economical in storage. The flutter solution is then obtained using an eigenvalue routine that has been developed to take advantage of the parametric nature of the V-g type of solution. Furthermore, the routine takes care of the fundamental and troublesome problem of properly sorting the output eigenvalues. By solving the root-sorting problem, the interpolation for flutter crossings and automatic plotting are accomplished efficiently. The computational techniques used in this new program are described and some sample results are given.

Desmarais, R. N.↗
NASA NTRS1951

Experimental Investigation of Air-Cooled Turbine Blades in Turbojet Engine. 7: Rotor-Blade Fabrication Procedures

An experimental investigation was conducted to determine the cooling effectiveness of a wide variety of air-cooled turbine-blade configurations. The blades, which were tested in the turbine of a - commercial turbojet engine that was modified for this investigation by replacing two of the original blades with air-cooled blades located diametrically opposite each other, are untwisted, have no aerodynamic taper, and have essentially the same external profile. The cooling-passage configuration is different for each blade, however. The fabrication procedures were varied and often unique. The blades were fabricated using methods most suitable for obtaining a small number of blades for use in the cooling investigations and therefore not all the fabrication procedures would be directly applicable to production processes, although some of the ideas and steps might be useful. Blade shells were obtained by both casting and forming. The cast shells were either welded to the blade base or cast integrally with the base. The formed shells were attached to the base by a brazing and two welding methods. Additional surface area was supplied in the coolant passages by the addition of fins or tubes that were S-brazed. to the shell. A number of blades with special leading- and trailing-edge designs that provided added cooling to these areas were fabricated. The cooling effectiveness and purposes of the various blade configurations are discussed briefly.

Long, Roger A.↗
NASA NTRS1974

A detailed procedure for the use of small-scale photography in land use classification

A procedure developed to produce accurate land use maps from available high-altitude, small-scale photography in a cost-effective manner is presented. An alternative procedure, for use when the capability for updating the resultant land use map is not required, is also presented. The technical approach is discussed in detail, and personnel and equipment needs are analyzed. Accuracy percentages are listed, and costs are cited. The experiment land use classification categories are explained, and a proposed national land use classification system is recommended.

Vegas, P. L.↗
NASA NTRS1974

Constant temperature hot wire anemometry data reduction procedure

The theory and data reduction procedure for constant temperature hot wire anemometry are presented. The procedure is valid for all Mach and Prandtl numbers, but limited to Reynolds numbers based on wire diameter between 0.1 and 300. The fluids are limited to gases which approximate ideal gas behavior. Losses due to radiation, free convection and conduction are included.

Klopfer, G. H.↗
NASA NTRS1973

A variable step incremental procedure

Description of a variable step incremental procedure for the solution of nonlinear equations in finite element structural analysis. The proposed procedure is effective in improving the accuracy of the basic incremental technique and in providing, in addition, an accurate estimate of the discretization error. The proposed approach is highly appropriate for solving problems for which the user has no a priori estimate of the step size to use.

Thomas, G. R.↗
NASA NTRS1974

Computational procedure for evaluation of space shuttle TPS requirements

The rudiments of a computational procedure are presented for predicting heat transfer rates to the windward pitchplane of a shuttle vehicle under conditions of nonequilibrium flow. The procedure involves computations in three regions of the flow field, namely, the stagnation region, inviscid flow region, and boundary layer region. The thermochemical state in the inviscid flow was calculated with the aid of correlations developed from shadowgraphs of shuttle configurations. The flow in the boundary layer and stagnation regions was computed with a nonequilibrium viscous layer code. For boundary layers, the outer edge thermochemical state was determined by matching the mass flow in the boundary layer with the mass flow represented by each inviscid streamline. Typical solutions are presented to show the effects of surface pressure, catalycity, and homogeneous chemical reactions on flow field variables and surface heat transfer rates.

Tong, H.↗
NASA NTRS1974

Viking planetary quarantine procedures and implementation

Some of the techniques and methodology that were used on Viking to implement planetary quarantine requirements are reported. Special attention was given to techniques and approaches used to implement sterilization of the Viking probe. Quarantine procedures for unmanned planetary missions and procedures for microbiological contamination of space hardware are included. A probability of contamination of the biological instruments onboard by terrestrial organisms was examined.

Howell, R.↗
NASA NTRS1975

Ground truth procedures, Phoenix soil moisture

Procedures used for collection of ground truth, in connection with passive gamma and microwave remote sensing are summarized. Soil moisture and vegetation sampling procedures are described.

Jones, E. B.↗
NASA NTRS1975

An improved numerical procedure for the parametric optimization of three dimensional scramjet nozzles

A parametric numerical procedure permitting the rapid determination of the performance of a class of scramjet nozzle configurations is presented. The geometric complexity of these configurations ruled out attempts to employ conventional nozzle design procedures. The numerical program developed permitted the parametric variation of cowl length, turning angles on the cowl and vehicle undersurface and lateral expansion, and was subject to fixed constraints such as the vehicle length and nozzle exit height. The program required uniform initial conditions at the burner exit station and yielded the location of all predominant wave zones, accounting for lateral expansion effects. In addition, the program yielded the detailed pressure distribution on the cowl, vehicle undersurface and fences, if any, and calculated the nozzle thrust, lift and pitching moments.

Dash, S.↗
NASA NTRS1973

A procedure for standardization of color infrared film response

Various problems with color infrared film used for remote sensing applications which relate to the instability or variability of the relative sensitivities of the dye layers within the film and the resultant variations in color balance are indicated. A procedure developed and utilized to optimize film response and to achieve more consistent results is described. The procedure establishes a sensitometric aim point with which all new batches of film are compared. Through the use of color compensation filters and change in basic exposure, the new film is exposed to produce imagery with the response characteristics of the aim curves.

Lapado, R. L.↗
NASA NTRS1975

Interim solar cell testing procedures for terrestrial applications

An interim draft of a set of test procedures, developed by NASA/ERDA, for the manufacture of solar cells is introduced. This version includes procedures for cell testing both outdoors in natural sunlight and indoors in simulated sunlight, a description of the necessary apparatus and equipment, the calibration and use of standard solar cells, and a proposed air-mass-two (AM2) solar spectrum.

Brandhorst, H.↗
NASA NTRS1975

JANNAF boundary layer integral matrix procedure

Accurate predictions of the thrust loss due to boundary layer effects and of the wall heat flux are very important to the design and performance evaluation of rocket nozzles. A method used in analytical procedures for liquid fuel rocket engine performance prediction and evaluation is presented. A computer program is examined that is a fast and accurate procedure for solving the set of boundary layer equation (momentum, energy, and species) for laminar or turbulent, chemically reacting flows with a wide variety of boundary conditions. Results of comparison of the various turbulent models are presented. A summary of the modifications and additions to the program is examined.

Evans, R. M.↗
NASA NTRS1975

Reliability-based optimum inspection and maintenance procedures

The development of reliability-based optimum inspection and maintenance schedules for engines needs an understanding of the fatigue behavior of the engines. Critical areas of the engine structure prone to fatigue damage are usually identified beforehand or after the fleet has been put into operation. In these areas, fatigue cracks initiate after several flight hours, and these cracks grow in length until failure takes place when these cracks attain the critical lengths. Crack initiation time and its growth rate are considered to be random variables. Usually, the inspection (fatigue) or test data from similar engines are used as prior distributions. The existing state-of-the-art is to ignore the different lengths of cracks obserbed at various inspections and to consider only the fact that a crack existed (or did not exist) at the time of inspection. In this paper, a procedure has been developed to obtain the probability of finding a crack of a given size at a certain time if the probability distributions for crack initiation and rates of growth are known. Application of the developed stochastic models to devise optimum procedures for inspection and maintenance are also discussed.

Nanagud, S.↗
NASA NTRS1975

Calculation of three-dimensional compressible laminar and turbulent boundary layers. An implicit finite-difference procedure for solving the three-dimensional compressible laminar, transitional, and turbulent boundary-layer equations

An implicit finite-difference procedure is presented for solving the compressible three-dimensional boundary-layer equations. The method is second-order accurate, unconditionally stable (conditional stability for reverse cross flow), and efficient from the viewpoint of computer storage and processing time. The Reynolds stress terms are modeled by (1) a single-layer mixing length model and (2) a two-layer eddy viscosity model. These models, although simple in concept, accurately predicted the equilibrium turbulent flow for the conditions considered. Numerical results are compared with experimental wall and profile data for a cone at an angle of attack larger than the cone semiapex angle. These comparisons clearly indicate that the numerical procedure and turbulence models accurately predict the experimental data with as few as 21 nodal points in the plane normal to the wall boundary.

Harris, J. E.↗
NASA NTRS1975

An investigation of several numerical procedures for time-asymptotic compressible Navier-Stokes solutions

The status of an investigation of four numerical techniques for the time-dependent compressible Navier-Stokes equations is presented. Results for free shear layer calculations in the Reynolds number range from 1000 to 81000 indicate that a sequential alternating-direction implicit (ADI) finite-difference procedure requires longer computing times to reach steady state than a low-storage hopscotch finite-difference procedure. A finite-element method with cubic approximating functions was found to require excessive computer storage and computation times. A fourth method, an alternating-direction cubic spline technique which is still being tested, is also described.

Rudy, D. H.↗