Results for “experimental data analysis” — Page 22

NASA NTRS2011

Assessment of Computational Fluid Dynamics (CFD) Models for Shock Boundary-Layer Interaction

A workshop on the computational fluid dynamics (CFD) prediction of shock boundary-layer interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses.

DeBonis, James R.↗

NASA NTRS2011

Continuum Damage Mechanics Models for the Analysis of Progressive Failure in Open-Hole Tension Laminates

The performance of a state-of-the-art continuum damage mechanics model for interlaminar damage, coupled with a cohesive zone model for delamination is examined for failure prediction of quasi-isotropic open-hole tension laminates. Limitations of continuum representations of intra-ply damage and the effect of mesh orientation on the analysis predictions are discussed. It is shown that accurate prediction of matrix crack paths and stress redistribution after cracking requires a mesh aligned with the fiber orientation. Based on these results, an aligned mesh is proposed for analysis of the open-hole tension specimens consisting of different meshes within the individual plies, such that the element edges are aligned with the ply fiber direction. The modeling approach is assessed by comparison of analysis predictions to experimental data for specimen configurations in which failure is dominated by complex interactions between matrix cracks and delaminations. It is shown that the different failure mechanisms observed in the tests are well predicted. In addition, the modeling approach is demonstrated to predict proper trends in the effect of scaling on strength and failure mechanisms of quasi-isotropic open-hole tension laminates.

Song, Kyonchan↗

NASA NTRS2014

Multi-Point Combustion System: Final Report

A low-NOx emission combustor concept has been developed for NASA's Environmentally Responsible Aircraft (ERA) program to meet N+2 emissions goals for a 70,000 lb thrust engine application. These goals include 75 percent reduction of LTO NOx from CAEP6 standards without increasing CO, UHC, or smoke from that of current state of the art. An additional key factor in this work is to improve lean combustion stability over that of previous work performed on similar technology in the early 2000s. The purpose of this paper is to present the final report for the NASA contract. This work included the design, analysis, and test of a multi-point combustion system. All design work was based on the results of Computational Fluid Dynamics modeling with the end results tested on a medium pressure combustion rig at the UC and a medium pressure combustion rig at GRC. The theories behind the designs, results of analysis, and experimental test data will be discussed in this report. The combustion system consists of five radially staged rows of injectors, where ten small scale injectors are used in place of a single traditional nozzle. Major accomplishments of the current work include the design of a Multipoint Lean Direct Injection (MLDI) array and associated air blast and pilot fuel injectors, which is expected to meet or exceed the goal of a 75 percent reduction in LTO NOx from CAEP6 standards. This design incorporates a reduced number of injectors over previous multipoint designs, simplified and lightweight components, and a very compact combustor section. Additional outcomes of the program are validation that the design of these combustion systems can be aided by the use of Computational Fluid Dynamics to predict and reduce emissions. Furthermore, the staging of fuel through the individually controlled radially staged injector rows successfully demonstrated improved low power operability as well as improvements in emissions over previous multipoint designs. Additional comparison between Jet- A fuel and a hydrotreated biofuel is made to determine viability of the technology for use with alternative fuels. Finally, the operability of the array and associated nozzles proved to be very stable without requiring additional active or passive control systems. A number of publications have been publish

Goeke, Jerry↗

NASA NTRS2017

Informal Statistics Help Desk

Back by popular demand, the JSC Biostatistics Laboratory and LSAH statisticians are offering an opportunity to discuss your statistical challenges and needs. Take the opportunity to meet the individuals offering expert statistical support to the JSC community. Join us for an informal conversation about any questions you may have encountered with issues of experimental design, analysis, or data visualization. Get answers to common questions about sample size, repeated measures, statistical assumptions, missing data, multiple testing, time-to-event data, and when to trust the results of your analyses.

Young, M.↗

NASA NTRS2018

Analysis of Progressive Damage in Cross-Ply and Quasi-Isotropic Panels Subjected to Quasi-Static Indentation

The performance of a three-dimensional continuum damage mechanics (CDM) model for intralaminar damage, coupled with a cohesive zone model for delamination, is examined for damage prediction in cross-ply and quasi-isotropic laminated plates subjected to quasi-static transverse indentation. Details of the CDM model based on the deformation gradient decomposition (DGD) method and the finite element (FE) modeling strategy are presented and discussed. Critical features of the damage model and FE modeling approach are assessed by comparing analysis predictions to experimental data for cross-ply and quasi-isotropic panels in which damage is dominated by complex interactions between matrix cracks and delaminations.

Song, Kyongchan↗

NASA NTRSDate not supplied

Crash Sled Testing of Triaxially-Braided CFRP for Improved Vehicular Crashworthiness

The Impact Dynamics Laboratory at NASA Glenn Research Center recently developed a pneumatically-actuated crash sled for investigating the crush behavior of structural elements for vehicular applications. The apparatus includes an adjustable striker mass and specimen support mass, which are mounted on separate rails. This setup provides two advantages over crash sleds with so-called fixed specimen supports: (i) it allows for multiple independent measurements of the crush response using different instruments, and (ii) the specimen support can be varied and its reaction can be explicitly measured. This paper describes the experimental setup and data analysis methodology and illustrates the capability of the sled for measuring the specific energy absorption (SEA) of triaxially-braided carbon/epoxy composite C-channels and corrugated plates. The corrugated plate had a higher SEA than the C-channel and the SEAs did not vary when the striker mass and velocity were changed so that incident energy was constant.

Charles R Ruggeri↗

NASA NTRS2020

Crash Sled Testing of Triaxially-Braided CFRP for Improved Vehicular Crashworthiness

The Impact Dynamics Laboratory at NASA Glenn Research Center recently developed a pneumatically-actuated crash sled for investigating the crush behavior of structural elements for vehicular applications. The apparatus includes an adjustable striker mass and specimen support mass, which are mounted on separate rails. This setup provides two advantages over crash sleds with so-called fixed specimen supports: (i) it allows for multiple independent measurements of the crush response using different instruments, and (ii) the specimen support can be varied and its reaction can be explicitly measured. This paper describes the experimental setup and data analysis methodology and illustrates the capability of the sled for measuring the specific energy absorption (SEA) of triaxially-braided carbon/epoxy composite C-channels and corrugated plates. The corrugated plate had a higher SEA than the C-channel and the SEAs did not vary when the striker mass and velocity were changed so that incident energy was constant.

Composite Material↗

NASA NTRSDate not supplied

Crash Sled Testing of Triaxially-Braided CFRP for Improved Vehicular Crashworthiness

The Impact Dynamics Laboratory at NASA Glenn Research Center recently developed a pneumatically-actuated crash sled for investigating the crush behavior of structural elements for vehicular applications. The apparatus includes an adjustable striker mass and specimen support mass, which are mounted on separate rails. This setup provides two advantages over crash sleds with so-called fixed specimen supports: (i) it allows for multiple independent measurements of the crush response using different instruments, and (ii) the specimen support can be varied and its reaction can be explicitly measured. This paper describes the experimental setup and data analysis methodology and illustrates the capability of the sled for measuring the specific energy absorption (SEA) of triaxially-braided carbon/epoxy composite C-channels and corrugated plates. The corrugated plate had a higher SEA than the C-channel and the SEAs did not vary when the striker mass and velocity were changed so that incident energy was constant.

Energy absorption↗

DOE OSTI2020

Electric Motor Thermal Management

Thermal management enables more efficient and cost-effective motors. This Annual Merit Review presentation describes the technical accomplishments and progress in electric motor thermal management R&D over the last year. This project supports a broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management.

47 OTHER INSTRUMENTATION↗

DOE OSTI2022

Electric Motor Thermal Management

Thermal management enables more efficient and cost-effective motors. This Annual Merit Review presentation describes the technical accomplishments and progress in electric motor thermal management R&D over the last year. This project supports a broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management.

ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2023

Electric Motor Thermal Management

Thermal management enables more efficient and cost-effective motors. This Annual Merit Review presentation describes the technical accomplishments and progress in electric motor thermal management R&D over the last year. This project supports a broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management.

ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2024

Measurement of the Pion Exclusive Electro-Production Cross-Section in the E12-19-006 Experiment in Hall-C at Jefferson Lab

One of the most effective methods for exploring the transition from hadronic degrees of freedom to quark-gluon degrees of freedom in Quantum Chromodynamics (QCD) is through the investigation of \exclusive" pion and kaon electro-production reactions at various Q2 and ?t values. The E12-19-006 experiment is conducted within the confi?nes of experimental Hall C at the Thomas Jefferson National Accelerator Facility, USA, for such studies. The primary aim of the experiment is to ?first enhance our comprehension of the pion electro-production cross-section and its form factor at Q2 = 0.38 and 0.42 GeV2. This is the fi?rst run period of the E12-19-006 experiment which ran in summer 2019. A more profound understanding of the pion electro-production reaction, 1H(e,e'?+)n, at low Q2 is deemed essential to employ this electro-production reaction (an indirect technique) for the high Q2 studies, thereby delving deeper into the realm of QCD. Consequently, this dissertation presents a thorough analysis of the experimental data acquired in the ?first run period of the E12-19-006 experiment. In pursuit of precision, a series of systematic studies (target boiling correction study, the elastic reaction cross-section measurements, study for determining vari- ous kinematics o?sets, etc.) are conducted to discern the accuracy of the analyzed data, a prerequisite for the use of Rosenbluth separation technique to separate the pion electro-production cross-section terms in t bins. The separated pion electro-production cross-section through the Rosenbluth separation technique is then used to extract the pion electromagnetic form factor. In this dissertation, the pion electro-production cross-section is carefully dissected into its four constituent components: longitudinal (?L), transverse (?T ), longitudinal-transverse (?LT ), and transverse-transverse (?TT ), using the full version of Rosenbluth separation technique for the Q2 = 0.38 GeV2. The technique is simultaneously fi?tted to the unseparated pion electro-production cross-sections at the three values of polarization of the virtual photon (?), i.e., ? = 0.286, 0.629 and 0.781. An iterative process is applied to re?ne the parameters of the model cross-sections until the yield ratio of experimental and Monte Carlo simulation converges. In this study, 21 iterations are conducted to re?ne the model cross-section parameters. The fi?nal pion electro-production cross-section terms are then determined for 7 t bins using the optimized parameters of the model cross-sections.

Kumar, Vijay↗

DOE OSTI2024

Workshop on Generalized Parton Distributions for Nucleon Tomography in the EIC Era

The aim of the workshop is to examine the theoretical components that need to be incorporated, challenges and opportunities in different LQCD formalisms for computing hadron properties non-perturbatively from the underlying fundamental theory, and the requirements for an analysis framework of experimental data. The outcome of the workshop will be a white paper, and the establishment of a collaborative effort aimed at tackling these challenges and ensuring that the resulting framework can be applied across the emerging theoretical and experimental programs.

99 GENERAL AND MISCELLANEOUS↗

NASA NTRS1980

Thermal microwave emissions from vegetated fields: A comparison between theory and experiment

The radiometric measurements over bare field and fields covered with grass, soybean, corn, and alfalfa were made with 1.4 GHz and 5 GHz microwave radiometers during August - October 1978. The measured results are compared with radiative transfer theory treating the vegetated fields as a two layer random medium. It is found that the presence of a vegetation cover generally gives a higher brightness temperature T(B) than that expected from a bare soil. The amount of this T(B) excess increases in the vegetation biomass and in the frequency of the observed radiation. The results of radiative transfer calculations generally match well with the experimental data, however, a detailed analysis also strongly suggests the need of incorporating soil surface roughness effect into the radiative transfer theory in order to better interpret the experimental data.

Wang, J. R.↗

NASA NTRS2008

A Finite Element Analysis for Predicting the Residual Compressive Strength of Impact-Damaged Sandwich Panels

A simple analysis method has been developed for predicting the residual compressive strength of impact-damaged sandwich panels. The method is tailored for honeycomb core-based sandwich specimens that exhibit an indentation growth failure mode under axial compressive loading, which is driven largely by the crushing behavior of the core material. The analysis method is in the form of a finite element model, where the impact-damaged facesheet is represented using shell elements and the core material is represented using spring elements, aligned in the thickness direction of the core. The nonlinear crush response of the core material used in the analysis is based on data from flatwise compression tests. A comparison with a previous analysis method and some experimental data shows good agreement with results from this new approach.

Ratcliffe, James G.↗

NASA NTRS2008

A Finite Element Analysis for Predicting the Residual Compression Strength of Impact-Damaged Sandwich Panels

A simple analysis method has been developed for predicting the residual compression strength of impact-damaged sandwich panels. The method is tailored for honeycomb core-based sandwich specimens that exhibit an indentation growth failure mode under axial compression loading, which is driven largely by the crushing behavior of the core material. The analysis method is in the form of a finite element model, where the impact-damaged facesheet is represented using shell elements and the core material is represented using spring elements, aligned in the thickness direction of the core. The nonlinear crush response of the core material used in the analysis is based on data from flatwise compression tests. A comparison with a previous analysis method and some experimental data shows good agreement with results from this new approach.

Ratcliffe, James G.↗

DOE OSTI2022

Overview of Nuclear Data Measurement and Analysis at RPI [Slides]

This presentation discusses the experimental, simulation, and nuclear data methods that were validated for the RPI γ-Multiplicity Detector. When the neutron capture γ-cascade data is well-known, the γ-emission spectra can be accurately calculated using the modified simulation tools. The RPI γ-Multiplicity Detector system is now ready for analysis and recommendations for isotopes with deficiencies in γ-ray data. The presentation also discusses future work which includes developing a method for analyzing and adjusting nuclear data for 59 Co, 55 Mn and other measured isotopes including 181 Ta. Additionally, future work includes comparing experimental γ-emission spectra with MCNP-6.2/DICEBOX simulations for 238 U and 235 U. In summation, new capture and transmission measurements for 54 Fe will help improve resonance parameter evaluation. Neutron capture gamma cascade spectra and yields were measured in the resolved resonance region and compared to evaluations. In addition, the pulsed neutron die-away method was developed as a tool to provide data for validation of TSLs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1979

Calculation of the three-dimensional flow field in supersonic inlets at angle of attack using a bicharacteristic method with discrete shock wave fitting

An analysis is presented for calculating the flow field in supersonic mixed-compression aircraft inlets operating at angle of attack. The flow field is computed by a steady three-dimensional bicharacteristic method. The bow shock wave and the reflected internal shock wave system are computed by a three-dimensional discrete shock wave fitting procedure. Viscous and thermal diffusion may be included as source terms in the bicharacteristic method. A production type computer program capable of determining the flow field in a variety of axisymmetric mixed-compression supersonic inlets is available. The results of the present analysis agree well with those produced by the two-dimensional method of characteristics when axisymmetric flow fields are computed. For three-dimensional flow fields, the results of the present analysis agree well with experimental data except in regions of high viscous interaction and boundary layer removal. The present analysis does not compute the boundary layer, nor does it account for boundary layer bleed.

Vadyak, J.↗