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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Additive Manufacture of Porous Zirconium Carbide for Nuclear Thermal Propulsion In-Core Insulators

Nuclear Thermal Propulsion (NTP) requires the use of in-core insulators to manage to thermal environment between high temperature fuel elements and lower temperature structural components. The unforgiving in-core operating conditions severely limit potential material candidates. Zirconium Carbide (ZrC) is a promising candidate due to a high melting temperature, high compressive strength, hardness, wear resistance, hydrogen compatibility, and low neutron absorption cross sections. However, fully dense ZrC is not an insulator but it has been found that the thermal conductivity of ZrC decreases by increasing porosity to approximately 60 % theoretical density (%TD). Previous methods for generating porous ZrC were difficult, expensive, and time consuming. Binder jet additive manufacture (AM) can print ceramic materials to near net shape. Binder jet AM is not utilized in many applications due to an inherently low post-sintering density on the order of 60 %TD. For this specific application the inherent lower density is leveraged as an advantage in production porous ZrC in order to control the thermal conductivity. A feasibility study was conducted to investigate binder jet AM parameter development for ZrC, heat treatment optimization (burn-out and sinter), microstructural characterization, mechanical testing, and thermal testing to generate near-net shape ZrC components with ~60 %TD with the desired thermal conductivity and mechanical strength.

Zirconium Carbide Additive Manufacture↗
NASA NTRS2021

The Dark Energy Survey Supernova Programme: Modelling Selection Efficiency and Observed Core-collapse Supernova Contamination

The analysis of current and future cosmological surveys of Type Ia supernovae (SNe Ia) at high redshift depends on the accuratephotometric classification of the SN events detected. Generating realistic simulations of photometric SN surveys constitutes anessential step for training and testing photometric classification algorithms, and for correcting biases introduced by selectioneffects and contamination arising from core-collapse SNe in the photometric SN Ia samples. We use published SN time-seriesspectrophotometric templates, rates, luminosity functions, and empirical relationships between SNe and their host galaxies toconstruct a framework for simulating photometric SN surveys. We present this framework in the context of the Dark EnergySurvey (DES) 5-yr photometric SN sample, comparing our simulations of DES with the observed DES transient populations.We demonstrate excellent agreement in many distributions, including Hubble residuals, between our simulations and data.We estimate the core collapse fraction expected in the DES SN sample after selection requirements are applied and beforephotometric classification. After testing different modelling choices and astrophysical assumptions underlying our simulation,we find that the predicted contamination varies from 7.2 to 11.7 per cent, with an average of 8.8 per cent and an r.m.s. of 1.1 percent. Our simulations are the first to reproduce the observed photometric SN and host galaxy properties in high-redshift surveyswithout fine-tuning the input parameters. The simulation methods presented here will be a critical component of the cosmologyanalysis of the DES photometric SN Ia sample: correcting for biases arising from contamination, and evaluating the associatedsystematic uncertainty.

M Vincenzi↗
NASA NTRS2020

Percussion Mechanism for the Mars2020 Coring Drill

The Mars2020 rover includes a Sampling & Caching Subsystem (SCS) that is required to acquire core samples of hard rocks and to abrade rocky surfaces flat and smooth in order to facilitate surface science. Hard, high strength rocks exhibit brittle failure modes, and can be drilled and chiseled efficiently using percussive impacts. The coring drill percussion mechanism was designed to provide those impacts with variable output force and to be used with various drill bits. A unique hammering mechanism, using a base-driven hammer, powered by a conventional rotary actuator driving a Scotch yoke, was designed to robustly provide the required function in a Martian environment for a life exceeding 2 million impacts.

Chrystal, Kyle↗
NASA NTRSDate not supplied

Finite Element Modeling for Compression Strength Prediction of Honeycomb Cores with Geometric Imperfections Measured using X-ray CT Imaging

Aluminum honeycomb cores have been used extensively in composite sandwich panels due to having high bending rigidity while maintaining low density. During manufacturing of the aluminum honeycomb, the thin metal walls are susceptible to imperfections that deviate from an ideal honeycomb shape. Computational tools to quantify imperfections and investigate their effects on quasi-static compression and impact response can inform design criteria to construct safer and lighter launch vehicle structures. This paper presents the results of a study on finite element modeling of metallic honeycomb cores (HCC) with geometric imperfections measured using X-ray Computer Tomography (CT), to predict the compression response. Finite element (FE) models are constructed with measured imperfections with appropriate boundary conditions. It is shown that the average behavior of larger 10x11 cell models can be predicted by sampling single cell models from the larger domain. Amplification of imperfections for cells at the center of sampled specimens are mode switched from the larger out-of-plane imperfection to the mode shape of the adjacent cells resulting in strengthening of the center specimens.

aluminum honeycomb↗
NASA NTRSDate not supplied

Hybrid Thermally Efficient Core (HyTEC) Project Overview

Goal: - The Hybrid Thermally Efficient Core (HyTEC) Project will accelerate the development of the next generation small-core turbofan engine technologies with improvements in efficiency, durability, performance, hybridization, and sustainability in order to meet the next Entry into Service (EIS) single aisle aircraft expected in the 2030’s. Objectives: - Achieve 5-10% fuel burn reduction versus 2020 best in class. - Achieve up to 20% power extraction (4 times current state of the art) at altitude to optimize propulsion system performance and enable hybridization. - Demonstrate the effective and efficient operability of high blend (>80%) Sustainable Aviation Fuels (SAFs) in 2030s EIS combustors.

Tony Nerone↗
NASA NTRS2024

Hybrid Thermally Efficient Core (HyTEC) HyTEC Phase 1 – Combustor Final Report

The objective of the HyTEC – Combustor Technology project is to develop technology for a compact, low emissions, rich-burn combustor that maintains a high-level of durability. To accomplish this, the combustor will incorporate CMC liners and a CMC Dome to enable improved air utilization for mixing and NOx reduction. In particular, three technology areas were matured: metallic swirler attachment to the CMC dome, Nickel diffusion in CMC, and EBC advancements with improved durability. The maturation of these technology areas is critical to successfully designing a combustor for an engine intended to demonstrate increased thermal efficiency with integrated high-power density-core engine technologies. As part of the project, multiple swirler attachment architectures were matured through the design process, manufactured, and tested in simulated engine conditions. These architectures utilized two different approaches to attachment: a pressure loaded approach and a clamped approach. Each approach required testing at simulated engine conditions to mature the technology. These tests were developed to ensure that the probable failure mechanisms for each architecture were assessed relative to its long-term durability. After successfully testing both approaches, the pressure loaded approach was chosen based on its simplicity and its similarity to the attachment approach used on lean burn combustors. Finally, this successful testing resulted in the swirler attachment technology achieving TRL 4 status. Another aspect of concern with the metallic swirler attachment is the potential for nickel diffusion into the CMC to cause durability shortfalls. A series of tests were completed to understand both the amount of nickel that is expected to diffuse into the CMC and the effect this diffusion will have on mechanical properties of the CMC. After successfully completing this testing, the reduction in local mechanical properties was found to not have an impact on the overall durability of the CMC Dome. To further improve the overall durability, three different EBC coating architectures were also studied. One of these coatings being the current state of the art for CMC liners with the other two being proposed improvements. Coupons were produced using each coating and subjected to a series of laboratory testing. One coating was found to have an overall superior durability in laboratory testing and survived rig testing without indication of degradation. This successful testing resulted in the EBC technology achieving TRL 5 status. Overall, a design approach was successfully down-selected that achieves both the TPM requirements and the need for TRL 4+ status. This design incorporates a pressure loaded swirler attachment with an improved EBC coating (Architecture 1). This combination allows the continued use of a CMC dome and results in an improved durability for the proposed compact core combustor.

CMC↗
NASA NTRSDate not supplied

Hybrid Thermally Efficient Core Project

The Hybrid Thermally Efficient Core (HyTEC) Project will accelerate the development of the next generation small-core turbofan through improvements in efficiency, durability, performance, hybridization, and sustainability to meet the next Entry into Service (EIS) single aisle aircraft expected in the 2030s. HyTEC directly benefits the Sustainable Flight National Partnership and US Aviation net zero carbon emissions goals.

HyTEC↗
NASA NTRS2016

NASA Phase2 Unlimited Rights Final Report Research and Technology for Aerospace Propulsion Systems (RTAPS) Task Order: ERA Advanced Core Compressor Technology Program

As part of the NASA Integrated Systems Research Program (ISRP), Environmentally Responsible Aviation (ERA) Project, NASA GRC and GE Aviation have partnered to investigate the technology barriers associated with improved fuel economy of large gas turbine engines. Crucial to improving fuel economy is the increase in pressure ratio (PR) of the core high pressure compressor (HPC). A key enabler to increasing HPC pressure ratios are new technology front stage airfoil designs that have higher efficiency, higher pressure ratios and improvements in front stage part-power operability. The purpose of this work is to design and test two high pressure ratio, high efficiency front block designs. The baseline design, hereafter referred to as Build 1, is similar to what would be found in a high efficiency 30:1 PR class HPC. A redesigned front block with improved blading will also be tested and hereafter be referred to as Build 2. The goal of Build 2 is to increase stage aero loading (increase stage pressure ratio) beyond Build 1 while maintaining equivalent efficiency and stall margin. The detailed inter-stage and traverse data from the two builds will be used to improve understanding of the complex flow physics at high-speed and part-speed conditions that impact performance and operability. By addressing, understanding and solving the challenges associated with aerodynamic losses and stage matching better design strategies can be incorporated in future core compressors with higher efficiency, thereby enabling improvement in mission fuel burn while still meeting operability requirements.

Axial Compressors↗
NASA NTRS1963

A MAGNETIC CORE VOLTAGE-TO-FREQUENCY CONVERTER

Controlling the frequency of a square-loop magnetic core oscillator using a dc voltage to give a voltage-to-frequency conversion for use in pulse frequency modulated telemetry systems

PFM TELEMETRY↗
NASA NTRS1965

Gas core reactors

Fuel containment and heat transfer in gaseous core fission reactors

GASEOUS FISSION REACTOR↗