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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

A full CI treatment of the 1A1, 1B1, and 3B1 states of SiH2

Full CI calculations are presented for the 1A1, 3B1, and 1B1 states of SiH2 at their respective equilibrium geometries and at geometries with the SiH bonds stretched. These results are compared with those obtained from single-reference and multireference CI calculations. The computed Te values agree well with the full CI results, provided that the effects of higher-than-double excitations are accounted for either by the Davidson correction or by a multireference approach. When the SiH bonds are stretched, the single-reference methods are not sufficiently flexible, and only CASSCF/MRCI achieves chemical accuracy (i.e., agrees with the full CI to 1 kcal/mol). Overall, the accuracy of the various approximate methods is very similar to that found for H2O, NH2, and CH2.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1988

Comparison of pressure distributions on model and full-scale NACA 64-621 airfoils with ailerons for wind turbine application

The aerodynamic similarity between a small (4-inch chord) wind tunnel model and a full-scale wind turbine blade (24-foot tip section with a 36-inch chord) was evaluated by comparing selected pressure distributions around the geometrically similar cross sections. The airfoils were NACA 64-621 sections, including trailing-edge ailerons with a width equal to 38 percent of the airfoil chord. The model airfoil was tested in the OSU 6- by 12-inch High Reynolds Number Wind Tunnel; the full-scale blade section was tested in the NASA Langley Research Center 30- by 60-foot Subsonic Wind Tunnel. The model airfoil contained 61 pressure taps connected by embedded tubes to pressure transducers. A belt containing 29 pressure taps was fixed to the full-scale section at midspan to obtain surface pressure data. Lift coefficients were obtained by integrating pressures, and corrections were made for the 3-D effects of blade twist and downwash in the blade tip section. The results of the two different experimental methods correlated well for angles of attack from minus 4 to 36 degrees and aileron reflections from 0 to 90 degrees.

Gregorek, G. M.↗
NASA NTRS1988

Effects of symmetric and asymmetric modes on transonic aeroelastic characteristics of full-span wing-body configurations

To accurately study the transonic aeroelastic characteristics, it is important to model the full aircraft configuration, including asymmetry. Recently, an accurate method of computing unsteady transonic flows on full-span wing-body configurations was developed using the transonic potential flow theory. In this work, the method is further developed to account for the aeroelasticity of full-span wing-body configurations. This is accomplished by simultaneously integrating the unsteady aerodynamic forces and modal structural equations of the wing-body configurations. To validate the method, aeroelastic computations are made for a wing-body configuration with a rectangular wing. The aeroelastic responses of this configuration are correlated with the responses of a similar isolated wing. The comparisons are favorable. Aeroelastic computations associated with symmetric and asymmetric modes are also made to study the influence of modal asymmetry on responses. This new development is further illustrated by computing aeroelastic characteristics of a typical fighter aircraft. The results from this study will be useful in accurately computing the transonic flutter boundaries of aircraft, including those associated with asymmetric modes.

Guruswamy, Guru P.↗
NASA NTRS1991

Full-scale investigation of aerodynamic interactions between a rotor and fuselage

A wind tunnel program has been conducted in the NASA Ames National Full-Scale Aerodynamics Complex to investigate the aerodynamic interactions between a full-scale helicopter main rotor and simple fuselage. This program provides the first complete, quantitative data base detailing the effects of a rotor on a full-scale fuselage. Steady fuselage and rotor loads were obtained as well as steady and unsteady fuselage pressures. Data were acquired over a range of rotor thrusts, advance ratios, and shaft tilts. As expected, results indicate that the largest effects on mean fuselage forces, moments, and surface pressures occur at low speeds and high rotor thrusts. Quantitative comparisons were made to determine the ability of small-scale tests to simulate the effect of the rotor on mean fuselage forces and pressures.

Norman, Thomas R.↗
NASA NTRS1992

Supersonic full-potential methods for missile body analysis

Accounts are presented of representative applications to missile bodies of arbitrary shape of methods based on the steady form of the full potential equation. The NCOREL and SIMP full-potential codes are compared, and their results are evaluated for the cases of an arrow wing and a wing-body configuration. Attention is given to the effect of cross-sectional and longitudinal geometries. Comparisons of surface pressure and longitudinal force and moment data for circular and elliptic bodies have shown that the full-potential methods yielded excellent results in attached-flow conditions. Results are presented for a conical star body, waveriders, the Shuttle Orbiter, and a highly swept wing-body cruising at Mach 4.

Pittman, James L.↗
NASA NTRS1992

Full-scale high angle-of-attack tests of an F/A-18

This paper presents an overview of high angle-of-attack tests of a full-scale F/A-18 in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center at Moffett Field, California. A production aircraft was tested over an angle-of-attack range of 18 to 50 deg and at wind speeds of up to 100 knots. These tests had three primary test objectives. Pneumatic and mechanical forebody flow control devices were tested at full-scale and shown to produce significant yawing moments for lateral control of the aircraft at high angles of attack. Mass flow requirements for the pneumatic system were found to scale with freestream density and speed rather than freestream dynamic pressure. Detailed measurements of the pressures buffeting the vertical tail were made and spatial variations in the buffeting frequency were found. The LEX fence was found to have a significant effect on the frequency distribution on the outboard surface of the vertical fin. In addition to the above measurements, an extensive set of data was acquired for the validation of computational fluid dynamics codes and for comparison with flight test and small-scale wind tunnel test results.

Meyn, Larry A.↗
NASA NTRS1993

Full-scale wind-tunnel tests of high-lift system modifications on a carrier based fighter aircraft

Modifications to the high-lift system of a full-scale F/A-I8A were tested in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at the NASA Ames Research Center in Moffett Field, California. The objective was to measure the effect of simple modifications on the aerodynamic performance of the high-lift system. The modifications included the placement of a straight fairing in the shroud cove above the trailing-edge flap and the addition of seals to prevent air leakage through the hinge lines of the leading-edge flap, the trailing-edge shroud, and the wing fold. The test was carried out on an actual F/A-18A with it's flaps deployed in the landing approach configuration. The angle of attack ranged from 0 to 16 degrees and the wind speed was 100 knots. At an angle of attack of 8 degrees, the trimmed lift coefficient was improved by 0.09 with all wing seals in place. This corresponds to a reduction in the approach speed for the F/A-I8A of about 5 knots. The seal along the wing fold hinge, a feature present on many naval aircraft, provided one third of the total increment in trimmed lift. A comparison of the full-scale wind-tunnel results with those obtained from flight test is also presented.

Meyn, Larry A.↗
NASA NTRS1993

Effect of forebody tangential slot blowing on flow about a full aircraft geometry

The effect of forebody tangential slot blowing on the flowfield about an F/A-18 aircraft is investigated numerically using solutions of the Navier-Stokes equations. Computed solutions are obtained for a full aircraft geometry, including the fuselage, wing with deflected leading-edge flap, empennage, and a faired-over engine inlet. The computational slot geometry corresponds to that used in full-scale wind tunnel tests. Solutions are computed using flight test conditions and jet mass flow ratios equivalent to wind tunnel test conditions. The effect of slot location is analyzed by computing two non-time-accurate solutions with a 16 in. slot located 3 in. and 11 in. aft of the nose of the aircraft. These computations resolve the trends observed in the full-scale wind tunnel test data. The flow aft of the leading edge extension (LEX) vortex burst is unsteady. A time-accurate solution is obtained to investigate the flow characteristics aft of the vortex burst, including the effect of blowing on tail buffet.

Gee, Ken↗
NASA NTRS1938

Wind-tunnel of three lateral-control devices in combination with a full-span slotted flap on an NACA 23012 airfoil

A large-chord NACA 23012 airfoil was tested. The airfoil extended completely across the test section, and two-dimensional flow was approximated. The model was fitted with a full-span slotted flap having a chord 25.66 percent of the airfoil chord. The ailerons investigated extended over the entire span and each had a chord 10 percent of the airfoil chord. The types of ailerons tested were: retractable ailerons, slot-lip ailerons using the lip of the slot for ailerons, and plain ailerons on the trailing edge of the slotted flap. The data are presented in the form of curves of section lift, drag, and pitching-moment coefficients for the airfoil with flap deflected but with ailerons neutral, and of rolling-moment, yawing-moment, and hinge-moment coefficients calculated for a rectangular wing of aspect ratio 6 with a semi-span aileron and a full-span flap. For the ailerons investigated the data indicate that, from considerations of rolling and yawing moments produced and of stick forces desired, the retractable aileron is the most satisfactory means of lateral control for use with a full-span slotted flap.

Wenzinger, Carl J↗
NASA NTRS1941

Tests of the NACA 0025 and 0035 Airfoils in the Full-Scale Wind Tunnel

This report presents the results of an investigation conducted in the NACA full-scale wind tunnel to determine the aerodynamic characteristics of the 6 by 36-foot rectangular NACA 0025 and 0035 airfoils. The aerodynamic characteristics of the plain airfoils with rounded and square tips were determined by force tests through a complete angle-of-attack range, in addition, the profile drag was determined by the momentum method. The transition points on the airfoils were located by boundary-layer determinations with small total-head and static tubes. Each airfoil was also tested with a 0.20c full-span split flap. Tuft surveys were included to show the progressive breakdown of flow with increasing angles of attack. Previously published data from tests of the NACA 0009, 0012, and 0018 airfoils in the full-scale tunnel have been included in the summary curves.

Bullivant, W Kenneth↗
NASA NTRS1993

Interpretation of lunar and planetary electromagnetic scattering using the full wave solutions

Bistatic radar experiments carried out during the Apollo 14, 15, and 16 missions provide a very useful data set with which to compare theoretical models and experimental data. Vesecky, et al. report that their model for near grazing angles compares favorably with experimental data. However, for angles of incidence around 80 degrees, all the analytical models considered by Vesecky, et al. predict values for the quasi-specular cross sections that are about half the corresponding values taken from the Apollo 16 data. In this work, questions raised by this discrepancy between the reported analytical and experimental results are addressed. The unified full wave solutions are shown to be in good agreement with the bistatic radar taken during Apollo 14 and 16 missions. Using the full wave approach, the quasi-specular contributions to the scattered field from the large scale surface roughness as well as the diffuse Bragg-like scattering from the small scale surface roughness are accounted for in a unified self-consistent manner. Since the full wave computer codes for the scattering cross sections contain ground truth data only, it is shown how it can be reliably used to predict the rough surface parameters of planets based on the measured data.

Bahar, E.↗
NASA NTRS1992

Solar full-disk magnetic field image receiving system and observation software

The paper introduces terminal hardware system of 10 cm high resolution full-disk magnetic field telescope among solar multi-channel telescope produced by Beijing Astronomical Observatory, and its software procedure by using imaging processing as well real time data collecting. These data were processed by Sun Workstation 470/4, including doing some spectrum analysis, the system is unique in the world now. It uses a set of CCD (1320 pixels plus 1035 pixels) of high resolution image explosion, also it has a set of fast and high resolution (1024 pixel plus 1024 pixel) image processor. Moreover, we can obtain higher time and space resolution about solar full-disk magnetic field and velocity field. This will provide excellent means in observation and studies of full-disk solar large-scale magnetic field and velocity field.

Xu, Yan↗
NASA NTRS1986

Optimum full-scale subsonic wind tunnel

The needs and reasons for performing full-scale subsonic research have been studied. Full-scale wind-tunnel requirements are described; recommended size, airspeed, acoustic capabilities, and flow quality are developed; and data-acquisition systems, productivity, automation, and some cost elements are discussed. It is proposed that the optimum full-scale, subsonic wind tunnel be large enough to accommodate aerodynamic and acoustic investigations on most advanced aircraft, which exhibit complex engine/lifting-surface flow-field interactions, including advanced rotorcraft.

Mort, K. W.↗
NASA NTRS1997

Full-Potential Modeling of Blade-Vortex Interactions

A study of the full-potential modeling of a blade-vortex interaction was made. A primary goal of this study was to investigate the effectiveness of the various methods of modeling the vortex. The model problem restricts the interaction to that of an infinite wing with an infinite line vortex moving parallel to its leading edge. This problem provides a convenient testing ground for the various methods of modeling the vortex while retaining the essential physics of the full three-dimensional interaction. A full-potential algorithm specifically tailored to solve the blade-vortex interaction (BVI) was developed to solve this problem. The basic algorithm was modified to include the effect of a vortex passing near the airfoil. Four different methods of modeling the vortex were used: (1) the angle-of-attack method, (2) the lifting-surface method, (3) the branch-cut method, and (4) the split-potential method. A side-by-side comparison of the four models was conducted. These comparisons included comparing generated velocity fields, a subcritical interaction, and a critical interaction. The subcritical and critical interactions are compared with experimentally generated results. The split-potential model was used to make a survey of some of the more critical parameters which affect the BVI.

Jones, Henry E.↗
NASA NTRS1993

Full-Scale Wind Tunnel Studies of F/A-18 Tail Buffet

Tail buffet studies were conducted on a full-scale, production, F/A-18, fighter aircraft in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center in Moffett Field, California. The F/A-18 was tested over an angle-of-attack range of 18deg to 50deg, a side-slip range of -15deg to 15deg, and at wind speeds of up to 100 knots. The maximum speed corresponds to a Reynolds number of 12.3 x 10(exp 6) based on mean aerodynamic chord and a Mach number of 0.15. The port, vertical tail fin was instrumented with thirty-two surface pressure transducers, arranged in four by four arrays on both sides on the fin. The aircraft was also equipped with a removable Leading Edge eXtension (LEX) fence that is used on F/A-18 aircraft to reduce tail buffet loads. Time-averaged, power-spectral analysis results are presented for the tail fin bending moment derived from the integrated pressure field. The results are only for the zero side-slip condition, both with and without the LEX fence. The LEX fence significantly reduces the magnitude of the root-mean-square pressures and bending moments. Scaling issues are addressed by comparing full-scale results for pressures at the 60%-span and 45%-chord location with published results of small-scale, F/A-18 tail-buffet tests. The comparison shows that the tail buffet frequency scales very well with length and velocity. Root-mean-square pressures and power spectra do not scale as well. The LEX fence is shown to reduce tail buffet loads at all model scales.

Meyn, Larry A.↗
NASA NTRS2001

SRM Internal Flow Tests and Computational Fluid Dynamic Analysis: CFD RSRM Full-Scale Analyses - Volume 2

This document presents the full-scale analyses of the CFD RSRM. The RSRM model was developed with a 20 second burn time. The following are presented as part of the full-scale analyses: (1) RSRM embedded inclusion analysis; (2) RSRM igniter nozzle design analysis; (3) Nozzle Joint 4 erosion anomaly; (4) RSRM full motor port slag accumulation analysis; (5) RSRM motor analysis of two-phase flow in the aft segment/submerged nozzle region; (6) Completion of 3-D Analysis of the hot air nozzle manifold; (7) Bates Motor distributed combustion test case; and (8) Three Dimensional Polysulfide Bump Analysis.

Source record↗
NASA NTRS1994

Review of Full-Scale F/A-18 Research at NASA Ames Research Center

Results of flow visualization and tail buffett studies conducted on a full-scale production F/A-18 fighter aircraft in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex are presented. Test conditions range between 20 degrees and 40 degrees angle of attack, 16 degrees and -16 degrees side-slip angle, and up to a Mach number of 0.15 (corresponding to a Reynolds number of 12.3 x 10(exp 6) based on mean aerodynamic chord). Flow visualization results include both surface and off-surface techniques that examine forebody, canopy, leading-edge extension, and wing flow fields. Unsteady pressures measured at 96 locations on the port tail fin are used to determine the effect of a removable leading-edge extension fence on tail buffet loads at high angle of attack. Analyses and comparisons include tail fin bending moment and wave velocities on the tail surface. Repeatability and scaling issues are assessed through comparison with measurements from previous full-scale tests and several small-scales tests.

Olson, Lawrence E.↗
NASA NTRS2003

Towards an Automated Full-Turbofan Engine Numerical Simulation

The objective of this study was to demonstrate the high-fidelity numerical simulation of a modern high-bypass turbofan engine. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled three-dimensional computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady-state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the three-dimensional component models are integrated into the cycle model via partial performance maps generated automatically from the CFD flow solutions using one-dimensional meanline turbomachinery programs. This paper reports on the progress made towards the full-engine simulation of the GE90-94B engine, highlighting the generation of the high-pressure compressor partial performance map. The ongoing work will provide a system to evaluate the steady and unsteady aerodynamic and mechanical interactions between engine components at design and off-design operating conditions.

Reed, John A.↗