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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 415 records · Page 23

Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system

Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

Huff, Ronald G.↗

Flight set 360L003 instrumentation final test report, volume 9

Post-flight instrumentation hardware and data evaluation for 360L003 is summarized. The 360L003 motors were equipped with Developmental Flight Instrumentation (DFI), Operational Flight Instrumentation (OFI), and Ground Environmental Instrumentation (GEI). The DFI was designed to measure strain, temperature, pressure, and vibration at various locations on the motor during flight. The DFI is used to validate engineering models in a flight environment. The OFI consists of six Operational Pressure Tranducers which monitor chamber pressure during flight. These pressure transducers are used in the SRB separation cue. GEI measures the motor case, igniter flange, and nozzle temperature prior to launch.

Source record↗

In-flight acoustic testing techniques using the YO-3A Acoustic Research Aircraft

This report discusses the flight testing techniques and equipment employed during air-to-air acoustic testing of helicopters at Ames Research Center. The in flight measurement technique used enables acoustic data to be obtained without the limitations of anechoic chambers or the multitude of variables encountered in ground based flyover testing. The air-to-air testing is made possible by the NASA YO-3A Acoustic Research Aircraft. This "Quiet Aircraft' is an acoustically instrumented version of a quiet observation aircraft manufactured for the military. To date, tests with the following aircraft have been conducted: YO-3A background noise; Hughes 500D; Hughes AH-64; Bell AH-1S; Bell AH-1G. Several system upgrades are being designed and implemented to improve the quality of data. This report will discuss not only the equipment involved and aircraft tested, but also the techniques used in these tests. In particular, formation flying position locations, and the test matrices will be discussed. Examples of data taken will also be presented.

Cross, J. L.↗

An Exploratory Data Mining Investigation for Constructing a Publicly Sourced Dataset of Foreign Hypersonic Tests

This document details a data mining exercise that resulted in an exploratory dataset of publicly reported foreign (non-US) hypersonic vehicle test events. Using a combination of targeted English language searches and country-specific queries, the study aggregates information from digital news media, official press releases, and social media posts. The resulting list of events captures the publicly available accounts of foreign hypersonic tests, although it does not represent an exhaustive record. Limitations such as inconsistent reporting, translation challenges, and the inherently provisional nature of open-source data are acknowledged. This dataset serves as an initial reference point for further inquiries into high-speed atmospheric phenomena and may facilitate future efforts to correlate these events with geophysical measurements.

33 ADVANCED PROPULSION SYSTEMS↗

The RBE-LET relationship for rodent intestinal crypt cell survival, testes weight loss, and multicellular spheroid cell survival after heavy-ion irradiation

This report presents data for survival of mouse intestinal crypt cells, mouse testes weight loss as an indicator of survival of spermatogonial stem cells, and survival of rat 9L spheroid cells after irradiation in the plateau region of unmodified particle beams ranging in mass from 4He to 139La. The LET values range from 1.6 to 953 keV/microns. These studies examine the RBE-LET relationship for two normal tissues and for an in vitro tissue model, multicellular spheroids. When the RBE values are plotted as a function of LET, the resulting curve is characterized by a region in which RBE increases with LET, a peak RBE at an LET value of 100 keV/microns, and a region of decreasing RBE at LETs greater than 100 keV/microns. Inactivation cross sections (sigma) for these three biological systems have been calculated from the exponential terminal slope of the dose-response relationship for each ion. For this determination the dose is expressed as particle fluence and the parameter sigma indicates effect per particle. A plot of sigma versus LET shows that the curve for testes weight loss is shifted to the left, indicating greater radiosensitivity at lower LETs than for crypt cell and spheroid cell survival. The curves for cross section versus LET for all three model systems show similar characteristics with a relatively linear portion below 100 keV/microns and a region of lessened slope in the LET range above 100 keV/microns for testes and spheroids. The data indicate that the effectiveness per particle increases as a function of LET and, to a limited extent, Z, at LET values greater than 100 keV/microns. Previously published results for spread Bragg peaks are also summarized, and they suggest that RBE is dependent on both the LET and the Z of the particle.

Non-NASA Center↗

Measurement and Reporting Guidelines for Solar Mirror Aging Tests Using Xenon Arc Lamp Exposure (XALE)

This technical report provides a guideline for accelerated aging tests on solar reflectors. Solar reflectors must have a high durability, with goal lifespans reaching 30 years. To test and develop state-of-the-art solar reflectors, relevant durability tests must be conducted. Existing guidelines for materials testing include isothermal testing, humidity testing, corrosion, etc., but many tests do not specify to include solar irradiance or address its relevance to solar reflector durability. The guideline focuses on test design and reporting guidelines for using Xenon Arc Lamp Exposure (XALE). The XALE environmental chambers can subject samples to a combination of relevant environmental factors including concentrated solar irradiance, heat, humidity, and weathering cycles. The guideline is meant to provide information on developing relevant test conditions, exposure times, reflectance characterization procedures, and data reporting.

14 SOLAR ENERGY↗

High temperature strain gage technology for gas turbine engines

This report summarizes the results of a six month study that addressed specific issues to transfer the Pd-13Cr static strain sensor to a gas turbine engine environment. The application issues that were addressed include: (1) evaluation of a miniature, variable potentiometer for use as the ballast resistor, in conjunction with a conventional strain gage signal conditioning unit; (2) evaluation of a metal sheathed, platinum conductor leadwire assembly for use with the three-wire sensor; and (3) subjecting the sensor to dynamic strain cyclic testing to determine fatigue characteristics. Results indicate a useful static strain gage system at all temperature levels up to 1350 F. The fatigue characteristics also appear to be very promising, indicating a potential use in dynamic strain measurement applications. The procedure, set-up, and data for all tests are presented in this report. This report also discusses the specific strain gage installation technique for the Pd-13Cr gage because of its potential impact on the quality of the output data.

Fichtel, Edward J.↗

In-flight acoustic testing techniques using the YO-3A acoustic research aircraft

This report discusses the flight testing techniques and equipment employed during air-to-air acoustic testing of helicopters at Ames Research Center. The in-flight measurement technique used enables acoustic data to be obtained without the limitations of anechoic chambers or the multitude of variables encountered in ground based flyover testing. The air-to-air testing is made possible by the NASA YO-3A Acoustic Research Aircraft. This 'Quiet Aircraft' is an acoustically instrumented version of a quiet observation aircraft manufactured for the military. To date, tests with the following aircraft have been conducted: YO-3A background noise; Hughes 500D; Hughes AH-64; Bell AH-1S; Bell AH-1G. Several system upgrades are being designed and implemented to improve the quality of data. This report will discuss not only the equipment involved and aircraft tested, but also the techniques used in these tests. In particular, formation flying, position locations, and the test matrices will be discussed. Examples of data taken will also be presented.

Cross, J. L.↗

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↗

Halogen Occultation Experiment (HALOE) gas cell life test program

The Halogen Occultation Experiment (HALOE) will use gas filter correlation radiometry to measure the atmospheric concentration profiles of HCl, HF, NO, and CH4 from the Upper Atmosphere Research Satellite. The need to contain the gases for the gas filter measurements has resulted in the development of gas cells and the need for a life test program to demonstrate that the gas cells will perform their functions for extended periods (several years) of time. This report describes the tests in the life test program, the test apparatus used, and the analysis techniques developed. The report also presents data obtained during the first 14 months of the test program.

Sullivan, E. M.↗

K-3 Refractory Corrosion Test Results, HAL24M2

This report summarizes the refractory corrosion data of the high-Al matrix of Direct Feed High-Level Waste (DFHLW) glasses generated to expand glass compositional ranges. Design of a 20 high-Al glass matrix, HAL24M2, was reported in Russell et al. (2025, in progress). The HAL24M2 glasses were tested for K-3 corrosion and the results are presented in this report. Corrosion of Monofrax K-3 refractory materials in the HAL24M2 glass melts was measured using a crucible-scale method. Two test conditions, 1150 °C/7days and 1200 °C/7days were applied. The melt-line neck corrosion depth of the test coupons was measured by micro-computed tomography (micro-CT). The measured K-3 neck corrosion values were compared to predicted values using the model in Vienna et al. (2024). The model slightly over-predicted the neck corrosion depth of these glasses.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

AGC-4 Specimen Post-Irradiation Examination Data Interim Report

This interim report documents preliminary results of the post-irradiation examination material property testing from the fourth advanced graphite creep (AGC), AGC 4, capsule specimens. This is the fourth of a series of six irradiation test trains planned as part of the AGC experiment to fully characterize the neutron irradiation effects and radiation creep behavior of current nuclear graphite grades to moderate dose levels (=7 dpa). The AGC 4 capsule was irradiated in the Idaho National Laboratory Advanced Test Reactor at a nominal temperature of 800°C and to a peak dose of 8 dpa. Half of the AGC-4 specimens were subjected to compressive stresses to induce irradiation creep. Post-irradiation testing and measurement results are reported with the exception of thermal testing, which is still in progress, and irradiation mechanical strength testing. Additionally, some specimens initially deemed too hot to be examined in the ART Graphite laboratory may still be measured. The data reported includes specimen dimensions for both stressed and unstressed specimens to establish the irradiation creep rates, mass and dimensional data necessary to derive density, elastic constants (Young?s modulus, shear modulus, and Poisson?s ratio) from ultrasonic time of flight velocity measurements, Young?s modulus from the fundamental frequency of vibration, and electrical resistivity. A more complete evaluation of trends in the material property changes, as well as irradiation-induced creep due to the irradiation environment and applied load on the specimens, will be discussed later in AGC 4 post-irradiation examination analysis reports.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Hypothesis testing via AI: Generating physically interpretable models of scientific data with machine learning (Full Technical Report)

Deep learning has demonstrated an exceptional ability to solve complex tasks (an engineering success); however, it has done so at the expense of the ability to generate new knowledge (a scientific failure). We propose an alternative framework—entitled Deep Symbolic Regression (DSR)—in which artificial neural networks (NNs) rapidly generate hypotheses about physical relationships among inputs. This framework bypasses the need to interpret an NN altogether, while still leveraging the representational power of deep learning. The resulting models are tractable mathematical expressions, which are inherently and readily human interpretable and can provide insights into underlying physical phenomena. Further, we fold this methodology into the scientific process by allowing the scientist to directly integrate a priori knowledge and beliefs to accelerate learning. We demonstrate this methodology on symbolic regression—the problem of rediscovering underlying expressions describing a dataset—and achieve state-of-the-art performance across a wide variety of symbolic regression problems. Further, we generalize our DSR framework to apply to the more general class of symbolic optimization problems, in which one seeks to optimize a sequence of symbols or “tokens” under a black-box reward function. Examples of other symbolic optimization problems include neural architecture search and computational antibody design. Our generalized tool, Deep Symbolic Optimization (DSO), has been demonstrated on the task of learning symbolic control policies for reinforcement learning environments, and has been adopted as an enabling capability for computational antibody design.

97 MATHEMATICS AND COMPUTING↗