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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2023

Robustness of Gridded Precipitation Products for Vietnam Basins using the Comprehensive Assessment Framework of Rainfall

The use of satellite–based precipitation products (SPPs) have become increasingly prevalent as key inputs to provide regional rainfall for improving hydrological simulations in data–spare regions. This study introduces a new approach – Comprehensive Assessment Framework of Rainfall (CAFR) to evaluate six satellite–based precipitation products (SPPs) for eleven basins with different sizes across Vietnam (2007–2015). These SPPs include the Global Precipitation Mission (GPM) Integrated Multi-satellitE Retrievals for Global Precipitation Measurement Final run Version 6 (GPM IMERGF V6), Multi–Source Weighted–Ensemble Precipitation (MSWEP) V2.2, Soil Moisture to Rain (SM2RAIN) – Advanced SCATterometer (ASCAT) V1.5, Asian Precipitation–Highly–Resolved Observational Data Integration Towards Evaluation (APHRODITE) V1901, Climate Hazards group Infrared Precipitation with Stations (CHIRPS) V2.0, and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) – Climate Data Record (CDR) V1.0. With the proposed CAFR: (1) IMERGF is suggested to have the best performance overall, especially when simulating flood peaks; (2) SM2RAIN–ASCAT demonstrates the best skills in metrics related to the dry season; (3) For streamflow simulations, SPPs' performance is sensitive to basin size, with larger basins showing better performance skills. In this study, we demonstrate the capability of our proposed framework to better understand SPP applications in hydrological modeling.

Comprehensive Assessment Framework of Rainfall (CA↗
NASA NTRS1985

A cosmic ray super high energy multicore family event. 2: Structure and fragmentation characteristics of the jets

Quarks and gluons are not directly observable, but may be displayed through fragmentation in the form of hadronic jets, the evidence of which was first revealed in cosmic ray interactions before the advent of the modern theory of strong interactions. Experimental results from ISR and SPPS collider rendered the jet phenomena more confident and definite. All the properties of jets observed up to now at ISR and SPPS collider are in agreement with the predictions of QCD. In order to make further test of QCD in still higher energy regions, detailed study of super high energy jet events in cosmic rays is very desirable. The event KO E19 observed in the Mt. Kambala emulsion chamber is an interesting event for such study. The general features of KO E19 is described. Its total visible energy is sigma E sub gamma = 1537 TeV(E sub min = 1.5 TeV) and production height H=(70 + or - 30)m, with a hadron as its primary particle. Besides about forty small clusters, there are five super high energy cores or jets, one lying near the center of the event while the other four surrounding it, having incident directions making small angles with that of the primary particle. Detailed analysis is done on the emulsion plates inserted in the chamber, making full use of their fine granularity, superior in detecting and analyzing jet events, specially their substructures.

Source record↗
NASA NTRS2015

The Solar Probe Plus Mission: Humanity's First Visit to Our Star

Solar Probe Plus (SPP) will be the first spacecraft to fly into the low solar corona. SPPs main science goal is to determine the structure and dynamics of the Suns coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Understanding these fundamental phenomena has been a top-priority science goal for over five decades, dating back to the 1958 Simpson Committee Report. The scale and concept of such a mission has been revised at intervals since that time, yet the core has always been a close encounter with the Sun. The mission design and the technology and engineering developments enable SPP to meet its science objectives to: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind; and (3) Explore mechanisms that accelerate and transport energetic particles. The SPP mission was confirmed in March 2014 and is under development as a part of NASAs Living with a Star (LWS) Program. SPP is scheduled for launch in mid-2018, and will perform 24 orbits over a 7-year nominal mission duration. Seven Venus gravity assists gradually reduce SPPs perihelion from 35 solar radii (RS) for the first orbit to less than 10 RS for the final three orbits. In this paper we present the science, mission concept and the baseline vehicle for SPP, and examine how the mission will address the key science questions.

Fox, N. J.↗
NASA NTRS2012

Development of YAG:Dy Thermographic Phosphor Coatings for Turbine Engine Applications

The selection and development of thermographic phosphor coatings were pursued to meet the objective of demonstrating luminescence-decay-based temperature measurements up to 1300C on the surface of a vane in an operating demonstrator turbine engine. To meet this objective, YAG:Dy was selected based on the desirable luminescence performance observed for YAG:Dy powder: (1) excellent temperature sensitivity and intensity at operating turbine engine temperatures, (2) an emission peak at the relatively short wavelength of 456 nm, where the interference from background blackbody radiation is fairly low, and (3) its nearly single exponential decay which makes for a simple, reliable temperature calibration. However, implementation of YAG:Dy for surface temperature measurements required application of YAG:Dy as a coating onto the surface of a superalloy component with a preexisting yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC). An inherent dilemma in producing a YAG:Dy coating is that coating processing is constrained to be performed at temperatures below (less than 1200C) what is considered safe for the superalloy component, much lower than temperatures used to produce the high quality crystalline powder. Therefore, YAG:Dy coatings tend to exhibit lower luminescence performance compared to well prepared YAG:Dy powder, and the luminescence performance of the coating will depend on the method of coating deposition. In this presentation, the luminescence performance of YAG:Dy coatings prepared by the different methods of (1) application of a binder-based YAG:Dy-containing paint, (2) solution precursor plasma spray (SPPS), and (3) electron-beam physical vapor deposition (EB-PVD) and the effect of post-deposition heat treatments will be discussed.

Eldridge, J. I.↗
NASA NTRS2015

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame Using a YAG:Tm Thermographic Phosphor

Luminescence-based surface temperature measurements were obtained from a YAG:Tm-coated stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing was to demonstrate that reliable surface temperatures based on luminescence decay of a thermographic phosphor producing short-wavelength emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative afterburner flame environment. YAG:Tm was selected as the thermographic phosphor for its blue emission at 456 nm (1D23F4 transition) and UV emission at 365 nm (1D23H6 transition) because background thermal radiation is lower at these wavelengths, which are shorter than those of many previously used thermographic phosphors. Luminescence decay measurements were acquired using a probe designed to operate in the afterburner flame environment. The probe was mounted on the sidewall of a high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick YAG:Tm thermographic phosphor layer was deposited by solution precursor plasma spray (SPPS). Spot temperature measurements were obtained by measuring luminescence decay times at different afterburner power settings and then converting decay time to temperature via calibration curves. Temperature measurements using the decays of the 456 and 365 nm emissions are compared. While successful afterburner environment measurements were obtained to about 1300C with the 456 nm emission, successful temperature measurements using the 365 nm emission were limited to about 1100C due to interference by autofluorescence of probe optics at short decay times.

thermographic phosphor↗