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Recent developments in the solar array manufacturing industry costing standards (SAMICS) are described. Consideration is given to the added capability to handle arbitrary operating schedules and the revised procedure for calculation of one-time costs. The results of an extensive validation study are summarized.
An airplane interior noise prediction model is developed to determine the important parameters associated with sound transmission into the interiors of airplanes, and to identify apropriate noise control methods. Models for stiffened structures, and cabin acoustics with floor partition are developed. Validation studies are undertaken using three test articles: a ring stringer stiffened cylinder, an unstiffened cylinder with floor partition, and ring stringer stiffened cylinder with floor partition and sidewall trim. The noise reductions of the three test articles are computed using the heoretical models and compared to measured values. A statistical analysis of the comparison data indicates that there is no bias in the predictions although a substantial random error exists so that a discrepancy of more than five or six dB can be expected for about one out of three predictions.
Stratospheric water vapor results taken from the limb infrared monitor of the stratosphere experiment on Nimbus 7 are presented with emphasis on validation studies. Basic radiance data, the indicated orbital precision of the experiment and comparisons made with data collected in simultaneous balloon underflights are described. A plot of pressure versus H2O channel radiance shows the radiance variability as a function of pressure and latitude. Measured precision is in good agreement with calculated values using simulations.
Fluid dynamic computer codes for the mathematical simulation of problems in gas turbine engine combustion systems are required as design and diagnostic tools. To eventually achieve a performance standard with these codes of more than qualitative accuracy it is desirable to use benchmark experiments for validation studies. Typical of the fluid dynamic computer codes being developed for combustor simulations is the TEACH (Teaching Elliptic Axisymmetric Characteristics Heuristically) solution procedure. It is difficult to find suitable experiments which satisfy the present definition of benchmark quality. For the majority of the available experiments there is a lack of information concerning the boundary conditions. A standard TEACH-type numerical technique is applied to a number of test-case experiments. It is found that numerical simulations of gas turbine combustor-relevant flows can be sensitive to the plane at which the calculations start and the spatial distributions of inlet quantities for swirling flows.
The objective of the research is to develop a processing system for analysis of HIRS2/MSU data on the TIROS/NOAA meteorological satellites to be used both to improve forecasting skill and to develop climatological data for at least a five year period. Research involves both the development of improved techniques and validation studies of the retrieved products.
The results of a validation study of data obtained by the Stratospheric Aerosol and Gas Experiment 2 satellite experiment (SAGE 2) are given. Preliminary SAGE 2 data have been available for the period October, 1984 to May, 1985. In addition, the results of two correlative experimental measurement series have been studied in detail, as well as climatological data obtained by other techniques, including ground-based and airborne lidar. The study shows the SAGE 2 data to be of great potential value to studies of the microphyiscs of stratospheric aerosols, the chemistry of trace gases and stratospheric dynamics. A small number of unidentified errors in the current preliminary data set are described. These will be removed from the next version of the data set which is anticipated to be of archival quality.
Comprehensive Silicon Solar Cell Computer Modeling (SICELL) program simulates silicon solar cell. Predicts device parameters as efficiency, voltage-vs.-current characteristic fill factor, and temperature coefficients of parameters. Technique used similar to numerical-integration methods, but commonality described by use of mesh-point field. Validation studies show accuracies of simulations range from 0.08 percent to 3.6 percent for 27 experimental data points over temperature range of 300K to 421K. Results obtained by use of 10 mesh points in n- and p-type regions and for two iterations. SICELL runs interactively on VAX computer under VMS and written in VAX/VMS FORTRAN 77.
The use of infrared radiance measurements made from high altitude aircraft for satellite image validation is discussed. Selected examples are presented to illustrate the techniques and the potentials of such validation studies.
Dissipation in elastic-plastic material calculated by two-dimensional finite-element method. Analytical procedure developed to calculate various components of dissipation of energy during extension of crack and to relate them to total dissipation of energy computed from global load-displacement response. Observations in study valid for other elastic-plastic fracture situations, including growth of cracks in pressure vessels in nuclear powerplants.
The proceedings are summarized from a pre-MASH planning workshop on the intercomparison of Southern Hemisphere observations, analyses and derived dynamical quantities held in Williamsburg, Virginia during April 1986. The aims of this workshop were primarily twofold: (1) comparison of Southern Hemisphere dynamical quantities derived from various satellite data archives (e.g., from limb scanners and nadir sounders); and (2) assessing the impact of different base-level height information on such derived quantities. These tasks are viewed as especially important in the Southern Hemisphere because of the paucity of conventional measurements. A further strong impetus for the MASH program comes from the recent discovery of the springtime ozone hold over Antarctica. Insight gained from validation studies such as the one reported here will contribute to an improved understanding of the role of meteorology in the development and evolution of the hold, in its interannual variability, and in its interhemispheric differences. The dynamical quantities examined in this workshop included geopotential height, zonal wind, potential vorticity, eddy heat and momentum fluxes, and Eliassen-Palm fluxes. The time periods and data sources constituting the MASH comparisons are summarized.
The National Aeronautics and Space Administration (NASA) Aircraft Noise Prediction Program (ANOPP) Propeller Analysis System (PAS) is a set of computational modules for predicting the aerodynamics, performance, and noise of propellers. The ANOPP PAS has the capability to predict noise levels for propeller aircraft certification and produce parametric scaling laws for the adjustment of measured data to reference conditions. A technical overview of the prediction techniques incorporated into the system is presented. The prediction system has been applied to predict the noise signature of a variety of propeller configurations including the effects of propeller angle of attack. A summary of these validation studies is discussed with emphasis being placed on the wind tunnel and flight test programs sponsored by the Federal Aviation Administration (FAA) for the Piper Cherokee Lance aircraft. A number of modifications and improvements have been made to the system and both DEC VAX and IBM-PC versions of the system have been added to the original CDC NOS version.
Most of the measurements of light-absorbing aerosol particles made previously have been in non-cloudy air and therefore provide no insight into aerosol effects on cloud properties. Here, researchers describe an experiment designed to measure light absorption exclusively due to substances inside cloud droplets, compare the results to related light absorption measurements, and evaluate possible effects on the albedo of clouds. The results of this study validate those of Twomey and Cocks and show that the measured levels of light-absorbing material are negligible for the radiative properties of realistic clouds. For the measured clouds, which appear to have been moderately polluted, the amount of elemental carbon (EC) present was insufficient to affect albedo. Much higher contaminant levels or much larger droplets than those measured would be necessary to significantly alter the radiative properties. The effect of the concentrations of EC actually measured on the albedo of snow, however, would be much more pronounced since, in contrast to clouds, snowpacks are usually optically semi-infinite and have large particle sizes.
Diabatic heating rate estimates as residuals of the dry thermodynamic equation were generated for May 1, 1985 to December 1989 in pentad resolution. Published results show moderate correlations (approx. .6) between heating rate and outgoing long wave radiation for periods under 90 days in the tropics and many extratropical locations. Nine years of simulation with the Community Climate Model 1 (CCM1) using R15 and observed sea surface temperatures shows that the model retains significantly more heat at the surface and in the free atmosphere than does the actual earth system. A post-processor for the CCM1, with capabilities to produce simulated microwave sounding unit (MSU) brightness temperatures was written. Techniques were refined considerably and validation studies were carried out to verify the globally distributed free atmosphere temperature anomalies derived from MSU data. The precision is such that detailed, long-term climate monitoring is well within the capability of these data.
A newly developed non-isotropic multiple scale turbulence model (MS/ASM) is described for complex flow calculations. This model focuses on the direct modeling of Reynolds stresses and utilizes split-spectrum concepts for modeling multiple scale effects in turbulence. Validation studies on free shear flows, rotating flows and recirculating flows show that the current model perform significantly better than the single scale k-epsilon model. The present model is relatively inexpensive in terms of CPU time which makes it suitable for broad engineering flow applications.
The purpose was to experimentally characterize the flow field created by the interaction of a single expansion ramp nozzle (SERN) flow with a hypersonic external stream. Data were obtained from a generic nozzle/afterbody model in the 3.5 Foot Hypersonic Wind Tunnel of the NASA Ames Research Center. The model design and test planning were performed in close cooperation with members of the National Aero-Space Plane (NASP) computational fluid dynamics (SFD) team, so that the measurements could be used in CFD code validation studies. Presented here is a description of the experiment, the extent of the measurements obtained, and the experimental results.
Quality assessment procedures are described for two-dimensional and three-dimensional unstructured meshes. The procedures include measurement of minimum angles, element aspect ratios, stretching, and element skewness. Meshes about the ONERA M6 wing and the Boeing 747 transport configuration are generated using an advancing front method grid generation package of programs. Solutions of Euler's equations for these meshes are obtained at low angle-of-attack, transonic conditions. Results for these cases, obtained as part of a validation study demonstrate the accuracy of an implicit upwind Euler solution algorithm.
The RPLUS3D code has been developed at the NASA Lewis Research Center to support the National Aerospace Plane (NASP) project. The code has the ability to solve three dimensional flowfields with finite rate combustion of hydrogen and air. The combustion process of the hydrogen-air system are simulated by an 18 reaction path, 8 species chemical kinetic mechanism. The code uses a Lower-Upper (LU) decomposition numerical algorithm as its basis, making it a very efficient and robust code. Except for the Jacobian matrix for the implicit chemistry source terms, there is no inversion of a matrix even though a fully implicit numerical algorithm is used. A k-epsilon turbulence model has recently been incorporated into the code. Initial validations have been conducted for a flow over a flat plate. Results of the validation studies are shown. Some difficulties in implementing the k-epsilon equations to the code are also discussed.
This paper describes a new trim procedure, that includes the calculation of the steady-state response of the rotor blades, and that is applicable to straight flight and steady coordinated turns. This paper also describes the results of a validation study for a high order linearized model of helicopter flight dynamics, that includes rotor, inflow, and actuator dynamics. The model is obtained by numerical perturbations of a nonlinear, blade element type mathematical model. Predicted responses are compared with flight test data for two values of flight speed. The comparison is carried out in the frequency domain. Numerical simulations show that the trim algorithm is very accurate, and preserves the periodicity of the aircraft states. The results also indicate that the predictions of the linearized model are in good agreement with flight test data, especially at medium and high frequencies.