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NASA NTRS2001

The Large-Scale Plasmaspheric Density Trough Associated With the 24 May 2000 Geomagnetic Storm: IMAGE EUV Observations and Global Core Plasma Modeling

The IMAGE EUV imager observed a plasmaspheric density, trough in association with a geomagnetically active period on 24 May 2000. In EUV, this density, trough appears as an Archimedes spiral extending from Earth's shadow to approximately 1900 MLT. We present an analysis of this density trough using simulated EUV images, Observational EUV images are subjected to edge analysis to establish the plasmapause L-shell and the location of the density trough in terms of L-shell, MLT extent, and radial width. The plasmaspheric density distribution is modeled using both static and dynamic models for the plasmasphere. The background plasmasphere is then numerically simulated using the 4-parameter plasmaspheric density model contained within the Global Core Plasma Model (GCPM) and the Dynamic Global Core Plasma Model (DGCPM). Simulated EUV images of the model plasmasphere are produced once an artificial density, depletion, matching the observed MLT extent and width, has been removed. Once the azimuthal extent and width of the trough have been simulated, the depth of the artificial density depletion is iteratively adjusted to produce simulated EUV images that approximate observation. The results of this analysis and discussion of possible origins for this density trough will be presented.

Adrian, M. L.↗

NASA NTRS1985

Parametric study of supersonic STOVL flight characteristics

A number of different control devices and techniques are evaluated to determine their suitability for increasing the short takeoff performance of a supersonic short-takeoff/vertical landing (STOVL) aircraft. Analysis was based on a rigid-body mathematical model of the General Dynamics E-7, a single engine configuration that utilizes ejectors and thrust deflection for propulsive lift. Alternatives investigated include increased static pitch, the addition of a close-coupled canard, use of boundary layer control to increase the takeoff lift coefficient, and the addition of a vectorable aft fan air nozzle. Other performance studies included the impact of individual E-7 features, the sensitivity to ejector performance, the effect of removing the afterburners, and a determination of optional takeoff and landing transition methods. The results pertain to both the E-7 and other configurations. Several alternatives were not as well suited to the E-7 characteristics as they would be to an alternative configuration, and vice versa. A large amount of supporting data for each analysis is included.

Rapp, David C.↗

NASA NTRS1971

Analysis of heat-transfer tests of an impingement-convection- and film-cooled vane in a cascade

Experimental flow and heat transfer data obtained for an air-cooled turbine vane tested in a static cascade at gas temperatures and pressures to 1644 K (2500 F) and 31 N/cm2 (45 psia), respectively, are presented. Average and local vane temperatures were correlated in several ways. Calculated and measured coolant flows and vane temperatures are compared. Potential allowable increases in gas temperature are also discussed.

Gladden, H. J.↗

NASA NTRS1985

Analysis of shell type structures subjected to time dependent mechanical and thermal loading

A general mathematical model and solution methodologies for analyzing structural response of thin, metallic shell-type structures under large transient, cyclic or static thermomechanical loads is considered. Among the system responses, which are associated with these load conditions, are thermal buckling, creep buckling and ratchetting. Thus, geometric as well as material-type nonlinearities (of high order) can be anticipated and must be considered in the development of the mathematical model.

Simitses, G. J.↗

NASA NTRS1980

Solid-propellant rocket motor internal ballistics performance variation analysis, phase 5

The results of research aimed at improving the predictability of internal ballistics performance of solid-propellant rocket motors (SRM's) including thrust imbalance between two SRM's firing in parallel are presented. Static test data from the first six Space Shuttle SRM's is analyzed using a computer program previously developed for this purpose. The program permits intentional minor design biases affecting the imbalance between any two SMR's to be removed. Results for the last four of the six SRM's, with only the propellant bulk temperature as a non-random variable, are generally within limits predicted by theory. Extended studies of internal ballistic performance of single SRM's are presented based on an earlier developed mathematical model which includes an assessment of grain deformation. The erosive burning rate law used in the model is upgraded and made more general. Excellent results are obtained in predictions of the performances of five different SRM's of quite different sizes and configurations. These SRM's all employ PBAN type propellants with ammonium perchlorate oxidizer and 16 to 20% aluminum except one which uses carboxyl terminated butadiene binder. The only non-calculated parameters in the burning rate equations that are changed for the different SRM's are the zero crossflow velocity burning rate coefficients and exponents. The results, in general, confirm the importance of grain deformation. The improved internal ballistic model makes practical development of an effective computer program for application of an optimization technique to SRM design which is also demonstrated. The program uses a pattern search technique to minimize the difference between a desired thrust-time trace and one calculated based on the internal ballistic model.

Sforzini, R. H.↗

NASA NTRS1989

Analysis of multilayered anisotropic plates - A new look at an old problem

The paper is concerned with the effects of variation in the lamination and geometric parameters of multilayered anisotropic plates on the accuracy of the static and vibrational responses predicted by six modeling approaches based on two-dimensional shear deformation theories. Extensive numerical results are presented for antisymmetrically laminated anisotropic rectangular plates. It is shown that, for most practical problems, the transverse shear deformation has a much more pronounced effect on the response of multilayered composite plates than that of transverse normal strain and stress. It is also shown that the accuracy of the predictions of the first-order deformation theory is strongly dependent on the values of the composite shear correction factors used.

Noor, Ahmed K.↗

NASA NTRS2001

The Use of Non-Standard Devices in Finite Element Analysis

A general mathematical description of the response behavior of thin-skin pneumatic envelopes and many other membrane and cable structures produces under-constrained systems that pose severe difficulties to analysis. These systems are mobile, and the general mathematical description exposes the mobility. Yet the response behavior of special under-constrained structures under special loadings can be accurately predicted using a constrained mathematical description. The static response behavior of systems that are infinitesimally mobile, such as a non-slack membrane subtended from a rigid or elastic boundary frame, can be easily analyzed using such general mathematical description as afforded by the non-linear, finite element method using an implicit solution scheme if the incremental uploading is guided through a suitable path. Similarly, if such structures are assembled with structural lack of fit that provides suitable self-stress, then dynamic response behavior can be predicted by the non-linear, finite element method and an implicit solution scheme. An explicit solution scheme is available for evolution problems. Such scheme can be used via the method of dynamic relaxation to obtain the solution to a static problem. In some sense, pneumatic envelopes and many other compliant structures can be said to have destiny under a specified loading system. What that means to the analyst is that what happens on the evolution path of the solution is irrelevant as long as equilibrium is achieved at destiny under full load and that the equilibrium is stable in the vicinity of that load. The purpose of this paper is to alert practitioners to the fact that non-standard procedures in finite element analysis are useful and can be legitimate although they burden their users with the requirement to use special caution. Some interesting findings that are useful to the US Scientific Balloon Program and that could not be obtained without non-standard techniques are presented.

Schur, Willi W.↗

NASA NTRS2000

IMAGE EUV Observations and Modeling of the Plasmaspheric Density Trough Associated with the 24 May 2000 Geomagnetic Storm

The IMAGE EUV imager observed a plasmaspheric density trough in association with a geomagnetically active period on 24 May 2000. At EUV wavelengths, this density trough appeared as an Archimedes spiral extending from Earth's shadow to approximately 1800 MLT. We present an analysis of this density trough using simulated EUV images. Observational EUV images are subjected to edge analysis to establish the plasmapause L-shell and the location of the density trough in terms of L-shell, MLT extent, and radial width. The plasmaspheric density distribution is modeled using both static and dynamic models for the plasmasphere. The background plasmasphere is then numerically simulated using the 4-parameter plasmaspheric density model contained within the Global Core Plasma Model (GCPM) [Gallagher et al., 20001 and the Dynamic Global Core Plasma Model (DGCPM). Simulated EUV images of the model plasmasphere are produced once an artificial density depletion, matching the observed MLT extent and width, has been removed. Once the azimuthal extent and width of the trough have been simulated, the depth of the artificial density depletion is iteratively adjusted to produce simulated EUV images that approximate observation. The results of this analysis and discussion of possible origins for this density trough will be presented.

Adrian, M.L.↗

NASA NTRS2009

Wind Tunnel Model Design for the Study of Plume Effects on Sonic Boom for Isolated Exhaust Nozzles

A low cost test capability was developed at the NASA Glenn Research Center 1- by 1-Foot Supersonic Wind Tunnel (SWT), with a goal to reduce the disturbance caused by supersonic aircraft flight over populated areas. This work focused on the shock wave structure caused by the exhaust nozzle plume. Analysis and design was performed on a new rig to test exhaust nozzle plume effects on sonic boom signature. Test capability included a baseline nozzle test article and a wind tunnel model consisting of a strut, a nose cone and an upper plenum. Analysis was performed on the external and internal aerodynamic configuration, including the shock reflections from the wind tunnel walls caused by the presence of the model nosecone. This wind tunnel model was designed to operate from Mach 1.4 to Mach 3.0 with nozzle pressure ratios from 6 to 12 and altitudes from 30,000 ft (4.36 psia) to 50,000 ft (1.68 psia). The model design was based on a 1 in. outer diameter, was 9 in. in overall length, and was mounted in the wind tunnel on a 3/8 in. wide support strut. For test conditions at 50,000 ft the strut was built to supply 90 psia of pressure, and to achieve 20 psia at the nozzle inlet with a maximum nozzle pressure of 52 psia. Instrumentation was developed to measure nozzle pressure ratio, and an external static pressure probe was designed to survey near field static pressure profiles at one nozzle diameter above the rig centerline. Model layout placed test nozzles between two transparent sidewalls in the 1x1 SWT for Schlieren photography and comparison to CFD analysis.

Castner, Raymond S.↗

NASA NTRS1973

Analytical and experimental study of supersonic combustion of hydrogen in a vitiated airstream

Detailed probe measurements of total temperature, pressure, and composition were taken in a two-dimensional test section 35.6 cm downstream of hydrogen injection. A high pressure gas generator supplied Mach 2.44 vitiated air or inert gas at elevated temperatures and at a static pressure equal to that of the hydrogen. Special water-cooled probes and sampling techniques were developed for the short test times required by heat-sink hardware. Independent methods of measuring stream total temperatures are compared. For the pure mixing case, the computed composition profile agreed well with the experimental profile. The analysis takes into account the wall boundary layer and the initial boundary layer in the main stream. Ignition of hydrogen, as determined from photographic exposures of the radiating gases, varied from 30 to 10 cm downstream from injection for a 45 K increase in local free-stream static temperature.

Burrows, M. C.↗

NASA NTRS2000

Thermal Analysis of ISS Service Module Active TCS

ISS Service Module mission must begin in July 2000. The verification of design thermal requirements is mostly due to thermal analysis. The thermal analysis is enough difficult problem because of large number of ISS configurations that had to be investigated and various orbital environments. Besides the ISS structure has articulating parts such as solar arrays and radiators. The presence of articulating parts greatly increases computation times and requires accurate approach to organization of calculations. The varying geometry needs us to calculate the view factors several times during the orbit, while in static geometry case we need do it only once. In this paper we consider the thermal mathematical model of SM that includes the TCS and construction thermal models and discuss the results of calculations for ISS configurations 1R and 9Al. The analysis is based on solving the nodal heat balance equations for ISS structure by Kutta-Merson method and analytical solutions of heat transfer equations for TCS units. The computations were performed using thermal software TERM [1,2] that will be briefly described.

Altov, Vladimir V.↗

NASA NTRS2023

Uncertainty Analysis of the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel 2019 Characterization Test 14-Foot, 5.8 Percent Test Section Porosity

This paper presents methods and results of a measurement uncertainty analysis that was performed for the 8- by 6-foot Supersonic Wind Tunnel located at the NASA Glenn Research Center. The uncertainty analysis is based on data collected during a characterization test following major structural modifications to the facility and upgrades to the facility’s data and control systems. The statistical methods and engineering judgments used to estimate elemental uncertainties are described in this report. The Monte Carlo method of propagating uncertainty was selected to determine the uncertainty of calculated variables of interest. A description of the Monte Carlo method as applied for this analysis is provided. The primary variable of interest (VOI) for this facility is free stream Mach number. In addition to determining the uncertainty in Mach number, the uncertainty in free stream values of static pressure, total pressure, dynamic pressure, total temperature, static temperature, Reynolds number, and air speed were also calculated. Uncertainty results are presented as random (unpredictable variation in repeated measurements), systematic (potential offset between observed and true value), and total (random and systematic combined) uncertainty for Mach number. Systematic uncertainty results are presented for the other VOIs. Individual uncertainty sources are presented both dimensionally and as percent contributions to uncertainty in all VOIs, to aid in the identification of primary uncertainty sources.

Uncertainty Analysis↗

NASA NTRS1981

Retrieval and use of high-resolution moisture and stability fields from Nimbus 6 HIRS radiances in pre-convective situations

A moisture-temperature retrieval scheme was developed for lower-tropospheric analysis and forecasting parameters from the Nimbus 6 High-resolution Infrared Radiation Sounder, in a study of convective development on the Great Plains of the U.S. on four case study days in August 1975. Dew points and temperatures, along with such secondary parameters as total precipitate water and static stability indices, were derived and analyzed at a horizontal resolution of up to 30 km on the four days. Convective development beginning 2.0-2.5 hours after the satellite pass at local noon was found to correlate well with local moisture and instability maxima seen in the satellite-derived analyses. A statistical structure analysis of the satellite-derived parameters gave the highest signal-to-noise values for the moisture and stability parameters, while the temperature parameters showed much lower signal-to-noise content.

Hillger, D. W.↗

NASA NTRS1918

An Investigation of the Elements which Contribute to Statical and Dynamical Stability, and of the Effects of Variation in Those Elements

Part 1 gives details of models tested and methods of testing of the Eiffel 36 wing alone and the JN2 aircraft. Characteristics and performance curves for standard JN are included. Part 2 presents a statistical analysis of the following: lift and drag contributed by body and chassis tested without wings; lift and drag contributed by tail, tested without wings; the effect on lift and drift of interference between the wings of a biplane combination; lift and drag contributed by the addition of body, chassis, and tail to a biplane combination; total parasite resistance; effect of varying size of tail, keeping angle of setting constant; effect of varying length of body and size of tail at the same time, keeping constant moment of tail surface about the center of gravity; forces on the tail and the effects of downwash; effect of size and setting of tail on statical longitudinal stability effects of length of body on stability; the effects of the various elements of an airplane on longitudinal stability and the placing of the force vectors. Part 3 presents the fundamental principals of dynamical stability; computations of resistance derivatives; solution of the stability equation; dynamical stability of the Curtiss JN2; tabulation of resistance derivatives; discussion of the resistance derivatives; formation and solution of stability equations; physical conceptions of the resistance derivatives; elements contributing to damping and an investigation of low speed conditions. Part 4 includes a summary of the results of the statistical investigation and a summary of the results for dynamic stability.

Klemin, Alexander↗

NASA NTRS1974

Advanced beaded and tubular structural panels. Volume 1: Design and analysis

A study was conducted to exploit the efficiency of curved elements in the design of lightweight structural panels under combined loads of axial compression, inplane shear, and bending. Data cover analytical procedures for optimum panel design, static strength analyses, results of panel design studies, and correlation of theory with test results.

Greene, B. E.↗

NASA NTRS1991

Analysis and testing of a space crane articulating joint testbed

The topics are presented in viewgraph form and include: space crane concept with mobile base; mechanical versus structural articulating joint; articulating joint test bed and reference truss; static and dynamic characterization completed for space crane reference truss configuration; improved linear actuators reduce articulating joint test bed backlash; 1-DOF space crane slew maneuver; boom 2 tip transient response finite element dynamic model; boom 2 tip transient response shear-corrected component modes torque driver profile; peak root member force vs. slew time torque driver profile; and open loop control of space crane motion.

Thomas R Sutter↗

NASA NTRS1973

User document for computer programs for ring-stiffened shells of revolution

A user manual and related program documentation is presented for six compatible computer programs for structural analysis of axisymmetric shell structures. The programs apply to a common structural model but analyze different modes of structural response. In particular, they are: (1) Linear static response under asymmetric loads; (2) Buckling of linear states under asymmetric loads; (3) Nonlinear static response under axisymmetric loads; (4) Buckling nonlinear states under axisymmetric (5) Imperfection sensitivity of buckling modes under axisymmetric loads; and (6) Vibrations about nonlinear states under axisymmetric loads. These programs treat branched shells of revolution with an arbitrary arrangement of a large number of open branches but with at most one closed branch.

Cohen, G. A.↗

NASA NTRS1974

The structure and circulation of the deep Venus atmosphere

A simple model for the structure of a nonrotating Hadley regime in an atmosphere with large thermal inertia is developed. The radiative fluxes are estimated by using a linearization about the radiative equilibrium state, and the dynamical fluxes are estimated by using scaling analysis. The requirement that differential heating by these fluxes be in balance in both the meridional and vertical directions leads to two equations for the mean static stability and meridional temperature contrast. The solution depends on two parameters: the strength of the radiative heating, as measured by the static stability of the radiative equilibrium state; and the ratio of the time it takes an external gravity wave to traverse the atmosphere to the time it would take the atmosphere to cool off radiatively. It is shown that it is not necessary to invoke convection to explain the approximate adiabatic lapse rate in the Venus atmosphere, but a greenhouse effect is necessary to explain the high surface temperatures.

Stone, P. H.↗