Results for “HC” — Page 8 | Engineering Papers

NASA NTRS2017

N+2 Advanced Low NOx Combustor Technology Final Report

In accordance with NASAs technology goals for future subsonic vehicles, this contract identified and developed new combustor concepts toward meeting N+2 generation (2020) LTO (landing and take-off) NOx emissions reduction goal of 75 from the standard adopted at Committee on Aviation Environmental Protection 6 (CAEP6). Based on flame tube emissions, operability, and autoignition testing, one concept was down selected for sector testing at NASA. The N+2 combustor sector successfully demonstrated 75 reduction for LTO NOx (vs. CAEP6) and cruise NOx (vs. 2005 B777-200 reference) while maintaining 99.9 cruise efficiency and no increase in CO and HC emissions.The program also developed enabling technologies for the combustion system including ceramic matrix composites (CMC) liner materials, active combustion control concepts, and laser ignition for improved altitude relight.

era↗

NASA NTRS2018

Properties of 5052 Aluminum For Use as Honeycomb Core in Manned Spaceflight

This work explains that the properties of Al 5052 material used commonly for honeycomb cores in sandwich panels are highly dependent on the tempering condition. It has not been common to specify the temper when ordering HC material nor is it common for the supplier to state what the temper is. For aerospace uses, a temper of H38 or H39 is probably recommended. This temper should be stated in the bill of material and should be verified upon receipt of the core. To this end some properties provided herein can aid as benchmark values.

tensile propertie↗

NASA NTRS2020

Propanal, an Interstellar Aldehyde - First Infrared Band Strengths and Other Properties of the Amorphous and Crystalline Forms

Chemical evolution in molecular clouds in the interstellar medium is well established, with the identification of over 200 molecules and molecular ions. Among the classes of interstellar organic compounds found are the aldehydes. However, laboratory work on the aldehydes has scarcely kept pace with astronomical discoveries as little quantitative solid-phase infrared (IR) data has been published on any of the aldehydes, and the same is true for important properties such as density, refractive indices, and vapor pressures. In this paper we examine the IR spectra of solid propanal (HC(O)CH2CH3, propionaldehyde), along with several physical properties, for both the amorphous and crystalline forms of the compound. The quantitative measurements we report, such as infrared intensities and optical constants, will be useful in laboratory investigations of the formation and evolution of propanal-containing ices, will serve as benchmark data for theoretical investigations, and will inform observational studies.

Yukiko Yagi Yarnall↗

NASA NTRS2021

Effective radiative forcing from emissions of reactive gases and aerosols - a multi-model comparison

This paper quantifies the pre-industrial (1850) to present-day (2014) effective radiative forcing (ERF) of anthropogenic emissions of NOX, volatile organic compounds (VOCs; including CO), SO2, NH3, black carbon, organic carbon, and concentrations of methane, N2O and ozone-depleting halocarbons, using CMIP6 models. Concentration and emission changes of reactive species can cause multiple changes in the composition of radiatively active species: tropospheric ozone, stratospheric ozone, stratospheric water vapour, secondary inorganic and organic aerosol, and methane. Where possible we break down the ERFs from each emitted species into the contributions from the composition changes. The ERFs are calculated for each of the models that participated in the AerChemMIP experiments as part of the CMIP6 project, where the relevant model output was available. The 1850 to 2014 multi-model mean ERFs (± standard deviations) are −1.03 ± 0.37 W/sq.m for SO2 emissions, −0.25 ± 0.09 W/sq.m for organic carbon (OC), 0.15 ± 0.17 W/sq.m for black carbon (BC) and −0.07 ± 0.01 W/sq.m for NH3. For the combined aerosols (in the piClim-aer experiment) it is −1.01 ± 0.25 W/sq.m. The multi-model means for the reactive well-mixed greenhouse gases (including any effects on ozone and aerosol chemistry) are 0.67 ± 0.17 W/sq.m for methane (CH4), 0.26 ± 0.07 W/sq.m for nitrous oxide (N2O) and 0.12 ± 0.2 W/sq.m for ozone-depleting halocarbons (HC). Emissions of the ozone precursors nitrogen oxides (NOx), volatile organic compounds and both together (O3) lead to ERFs of 0.14 ± 0.13, 0.09 ± 0.14 and 0.20 ± 0.07 W/sq.m respectively. The differences in ERFs calculated for the different models reflect differences in the complexity of their aerosol and chemistry schemes, especially in the case of methane where tropospheric chemistry captures increased forcing from ozone production.

radiative forcing↗

NASA NTRS2022

Clean Air Shower Curtain for Protection of Contamination Sensitive Telescopes on the Ariane 5 Launcher

The launch of the James Webb Space Telescope (JWST) was successfully performed by Ariane 5 from French Guiana on December 25th 2021. The unique nature of the JWST mission led to various adaptations of the Ariane 5 launch system to fulfill stringent cleanliness and hygrometry requirements all along the launch preparation. JWST integration and test activities in the Final Assembly Building (BAF) had to be performed in ISO Class 7 equivalent conditions under Volatile Organic Compounds (VOC) protection and monitoring. For this purpose, a dedicated air supply system equipped with Airborne Molecular Contamination (AMC) filters was installed in the umbilical mast. The fairing itself was specially sealed to protect the inner environment, and to, guarantee ISO Class 7, the BAF Composite Hall (BAF-HC) facilities were upgraded with a removable “Air Shower Curtain” (AShC) containment enclosure between the mobile platforms around JWST. The preparation of these Ariane 5 launch system adaptations started several years before the launch campaign with close cooperation and coordination between Arianespace, ArianeGroup, the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). This paper describes their specificities and addresses the challenges experienced to achieve the successful mission preparation.

Contamination Control, James Webb Space Telescope,↗

NASA NTRS2022

Clean Air Shower Curtain for Protection of Contamination Sensitive Telescopes on the Ariane 5 Launcher

The launch of the James Webb Space Telescope (JWST) was successfully performed by Ariane 5 from French Guiana on December 25th 2021. The unique nature of the JWST mission led to various adaptations of the Ariane 5 launch system to fulfill stringent cleanliness and hygrometry requirements all along the launch preparation. JWST integration and test activities in the Final Assembly Building (BAF) had to be performed in ISO Class 7 equivalent conditions under Volatile Organic Compounds (VOC) protection and monitoring. For this purpose, a dedicated air supply system equipped with Airborne Molecular Contamination (AMC) filters was installed in the umbilical mast. The fairing itself was specially sealed to protect the inner environment, and to, guarantee ISO Class 7, the BAF Composite Hall (BAF-HC) facilities were upgraded with a removable “Air Shower Curtain” (AShC) containment enclosure between the mobile platforms around JWST. The preparation of these Ariane 5 launch system adaptations started several years before the launch campaign with close cooperation and coordination between Arianespace, ArianeGroup, the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). This paper describes their specificities and addresses the challenges experienced to achieve the successful mission preparation.

Contamination Control, James Webb Space Telescope,↗

NASA NTRS2024

Replicating the Hadley Cell Edge and Subtropical Jet Latitude Disconnect in Idealized Atmospheric Models

Recent work has shown that variability in the subtropical jet's (STJ) latitude, ϕSTJ, is not coupled to that of the Hadley cell (HC) edge, ϕHC, but the robustness of this disconnect has not been examined in detail. Here, we use meteorological reanalysis products, comprehensive climate models, and an idealized atmospheric model to determine the necessary processes for a disconnect between ϕHC and ϕSTJ in the Northern Hemisphere's December–January–February season. We find that a decoupling can occur in a dry general circulation model, indicating that large-scale dynamical processes are sufficient to reproduce the metrics' relationship. It is therefore not reliant on explicit variability in the zonal structure, convection, or radiation. Rather, the disconnect requires a sufficiently realistic climatological basic state. Further, we confirm that the robust disconnect between ϕSTJ and ϕHC across the model hierarchy reveals their differing sensitivities to midlatitude eddy momentum fluxes; ϕHC is consistently coupled to the latitude of maximum eddy momentum flux, but ϕSTJ is not.

Molly E. Menzel↗