Search NASA⌕ Search

SEARCH · Search NASA

Results for “Experimental Data”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

A Computational Icing Effects Study for a Three-Dimensional Wing: Comparison with Experimental Data and Investigation of Spanwise Variation

Steady-state solutions of the Reynolds-averaged Navier-Stokes (RANS) equations were computed using the Colbalt flow solver for a constant-section, rectangular wing based on an extruded two-dimensional glaze ice shape. The one equation Spalart-Allmaras turbulence model was used. The results were compared with data obtained from a recent wind tunnel test. Computed results indicate that the steady RANS solutions do not accurately capture the recirculating region downstream of the ice accretion, even after a mesh refinement. The resulting predicted reattachment is farther downstream than indicated by the experimental data. Additionally, the solutions computed on a relatively coarse baseline mesh had detailed flow characteristics that were different from those computed on the refined mesh or the experimental data. Steady RANS solutions were also computed to investigate the effects of spanwise variation in the ice shape. The spanwise variation was obtained via a bleeding function that merged the ice shape with the clean wing using a sinusoidal spanwise variation. For these configurations, the results predicted for the extruded shape provided conservative estimates for the performance degradation of the wing. Additionally, the spanwise variation in the ice shape and the resulting differences in the flow fields did not significantly change the location of the primary reattachment.

Thompson, D.↗
NASA NTRS2017

Hover Performance of Isolated Proprotors and Propellers - Experimental Data

The use of Computational Fluid Dynamics (CFD) is gaining momentum within the aeronautical community. A relatively small segment of this community is applying CFD technology in the prediction of VSTOL aircraft performance. An even smaller group of engineers are refining and applying fluid dynamics solvers to the problem of predicting hover performance of helicopter rotors and proprotors designed by rotorcraft advocates. This small group of CFD engineers who are attacking the hover performance problem have, today, been using a quite limited experimental data base upon which to demonstrate their progress. This is because their concentration has been on only two successful tiltrotor flying; namely the XV-15 and the MV-22B. No attention appears (as yet) to be directed at the CL-84 or the XC-142A. The purpose of this report is to expand the experimental data base of both proprotors and propellers so that comparisons of test and various theories can be made to several more configurations of these propulsive devices used by VSTOL aircraft.

Hover↗
NASA NTRS1991

The analysis of high pressure experimental data

This letter is concerned with the analysis of high pressure experimental data. It is demonstrated that ln H plots based on the Vinet et al. (1988) universal equation of state are a simple sensitive means for identifying anomalous P-V data in high pressure experiments and for detecting structural and phase transitions in solids subjected to high pressure.

Schlosser, Herbert↗
NASA NTRS1975

Solution of the three-dimensional compressible, laminar, and turbulent boundary-layer equations with comparisons to experimental data

A technique for solving three-dimensional boundary-layer flows is presented. The governing equations are transformed to obtain a nondimensional form and a similarity-type transform is defined for the normal coordinate and velocity. The resulting equation is solved in an iterative mode using a finite difference technique suggested by Dwyer (1968). A simple mean field turbulence model is discussed and numerical data obtained in a test case are compared with experimental data.-

Harris, J. E.↗
NASA NTRS2008

Comparison of NTF Experimental Data with CFD Predictions from the Third AIAA CFD Drag Prediction Workshop

Recently acquired experimental data for the DLR-F6 wing-body transonic transport con figuration from the National Transonic Facility (NTF) are compared with the database of computational fluid dynamics (CFD) predictions generated for the Third AIAA CFD Drag Prediction Workshop (DPW-III). The NTF data were collected after the DPW-III, which was conducted with blind test cases. These data include both absolute drag levels and increments associated with this wing-body geometry. The baseline DLR-F6 wing-body geometry is also augmented with a side-of-body fairing which eliminates the flow separation in this juncture region. A comparison between computed and experimentally observed sizes of the side-of-body flow-separation bubble is included. The CFD results for the drag polars and separation bubble sizes are computed on grids which represent current engineering best practices for drag predictions. In addition to these data, a more rigorous attempt to predict absolute drag at the design point is provided. Here, a series of three grid densities are utilized to establish an asymptotic trend of computed drag with respect to grid convergence. This trend is then extrapolated to estimate a grid-converged absolute drag level.

Vassberg, John C.↗
NASA NTRS1991

A study of high-temperature heat pipes with multiple heat sources and sinks. I - Experimental methodology and frozen startup profiles. II - Analysis of continuum transient and steady-state experimental data with numerical predictions

Experimental profiles for heat pipe startup from the frozen state were obtained, using a high-temperature sodium/stainless steel pipe with multiple heat sources and sinks to investigate the startup behavior of the heat pipe for various heat loads and input locations, with both low and high heat rejection rates at the condensor. The experimental results of the performance characteristics for the continuum transient and steady-state operation of the heat pipe were analyzed, and the performance limits for operation with varying heat fluxes and location are determined.

Faghri, A.↗
NASA NTRSDate not supplied

Assessment of Particle Drag Models Using L2K and GBK Experimental Data

Properly assessing the drag force is an important element to computing the trajectories of particles traveling through a shock layer. This study will use experimental data in the German Aerospace Center (DLR) L2K arcjet to evaluate the ability of various particle drag models to reproduce the experimental particle velocity data.

particle flows↗
NASA NTRS1994

Issues concerning the updating of finite-element models from experimental data

Some issues concerning the updating of dynamic finite-element models by incorporation of experimental data are examined here. It is demonstrated how the number of unknowns can be greatly reduced if the physical nature of the model is maintained. The issue of uniqueness is also examined and it is shown that a number of previous workers have been mistaken in their attempts to define both sufficient and necessary measurement requirements for the updating problem to be solved uniquely. The relative merits of modal and frequency response function (frf) data are discussed and it is shown that for measurements at fewer degrees of freedom than are present in the model, frf data will be unlikely to converge easily to a solution. It is then examined how such problems may become more tractable by using new experimental techniques which would allow measurements at all degrees of freedom present in the mathematical model.

Dunn, Shane A.↗
NASA NTRS1990

Methods for determining the internal thrust of scramjet engine modules from experimental data

Methods for calculating zero-fuel internal drag of scramjet engine modules from experimental measurements are presented. These methods include two control-volume approaches, and a pressure and skin-friction integration. The three calculation techniques are applied to experimental data taken during tests of a version of the NASA parametric scramjet. The methods agree to within seven percent of the mean value of zero-fuel internal drag even though several simplifying assumptions are made in the analysis. The mean zero-fuel internal drag coefficient for this particular engine is calculated to be 0.150. The zero-fuel internal drag coefficient when combined with the change in engine axial force with and without fuel defines the internal thrust of an engine.

Voland, Randall T.↗
NASA NTRS2012

Prediction of BVI Noise for an Active Twist Rotor Using a Loosely Coupled CFD/CSD Method and Comparison to Experimental Data

Numerical predictions of the acoustic characteristics of an Active Twist Rotor (ATR), using two methods to compute the rotor blade aerodynamics and elastic blade motion are compared to experimental data from a wind tunnel test in the NASA Langley Transonic Dynamics Tunnel (TDT) in 2000. The first method, a loosely coupled iterative method, utilizes the Computational Fluid Dynamics (CFD) code OVERFLOW 2 and the Computational Structural Dynamics (CSD) code CAMRAD II. The second method utilizes the CAMRAD II free-wake model only. The harmonic active-twist control to the main rotor blade system is identified with three parameters - harmonic actuation frequency, actuation amplitude, and control phase angle. The resulting aerodynamics and blade motion data from the two methods are then used in the acoustics code PSU-WOPWOP to predict acoustic pressure on a spherical array of equally spaced observers surrounding the rotor. This spherical distribution of pressure is used to compute the sound power level representing baseline and actuated conditions. Sound power levels for three categories of noise are defined as - blade-vortex interaction sound power level (BVIPWL), low frequency sound power level (LFPWL), and overall sound power level, OAPWL. Comparisons with measured data indicate the CFD/CSD analysis successfully captures the trends in sound power levels and the effects of active-twist control at advance ratios of 0.14 and 0.17. The free-wake model predictions show inconsistent sound power levels relative to the trends in the experimental and CFD data. This paper presents the first ever comparison between CFD/CSD acoustic predictions for an active-twist rotor and experimental measurements.

Fogarty, David E.↗
NASA NTRS1971

Skin-stringer panel normal mode response experimental data and finite element computer program documentation

Detailed information is presented for the analytical and the experimental programs described in the report on Effects of Design Details on Structural Response to Acoustic Excitation, NASA CR-1959. This is a supplement to the basic report and detailed experimental data from all the specimens described in that report are discussed and presented in tabular form.

Rudder, F. F., Jr.↗
DOE OSTI2024

Evaluating the 238 U PFNS Including Chi-Nu Experimental Data

This report documents an evaluation of 238 U prompt fission neutron spectra (PFNS) which is a deliverable for a FY2024 Q4 NCSP (Nuclear Criticality Safety Program) milestone. This evaluation is new; its prior input is based on extended Los Alamos and exciton models implemented in the code CoH. Experimental covariances were estimated for five experimental data sets. One of these data sets that was measured by the Chi-Nu team of LANL and LLNL. It covers the 238 U PFNS for continuous incident-neutron energies of 1–20 MeV and outgoing-neutron energies from 10 keV– 10 MeV with high precision. Contrary to Chi-Nu data, previous data sets were measured in a limited energy range. The resulting evaluated data correspond well to the experimental PFNS taken into account for the evaluation. The evaluated PFNS also produce average mean energies in agreement with associated Chi-Nu data. If one uses the new evaluated data to predict the neutron multiplication factor, k eff , of the Flattop, Flattop-Pu and BigTen ICSBEP critical assemblies (which all have thick reflectors with high percentages of 238 U), the differences of simulated values compared to those using ENDF/B-VIII.1β3 is modest (less than 25 pcm). In addition to that, the new PFNS predict on average 238 U LLNL pulsed-sphere neutron-leakage spectra slightly better than ENDF/BVIIII.0 and ENDF/B-VIII.1β3 PFNS. The differences are, however, well within the experimental uncertainties.

238U↗