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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

A system simulation development project: Leveraging resources through partnerships

Partnerships between government agencies are an intellectually attractive method of conducting scientific research; the goal is to establish mutually beneficial participant roles for technology exchange that ultimately pays-off in a stronger R&D program for each partner. Anticipated and current aerospace research budgetary pressures through the 90's provide additional impetus for Government research agencies to candidly assess their R&D for those simulation activities no longer unique enough to warrant 'going it alone,' or for those elements where partnerships or teams can offset development costs. This paper describes a specific inter-agency system simulation activity that leverages the development cost of mutually beneficial R&D. While the direct positive influence of partnerships on complex technology developments is our main thesis, we also address on-going teaming issues and hope to impart to the reader the immense indirect (sometimes immeasurable) benefits that meaningful interagency partnerships can produce.

Drummond, Colin K.↗
NASA NTRS1983

Evaluation of the synoptic and mesoscale predictive capabilities of a mesoscale atmospheric simulation system

The overall performance characteristics of a limited area, hydrostatic, fine (52 km) mesh, primitive equation, numerical weather prediction model are determined in anticipation of satellite data assimilations with the model. The synoptic and mesoscale predictive capabilities of version 2.0 of this model, the Mesoscale Atmospheric Simulation System (MASS 2.0), were evaluated. The two part study is based on a sample of approximately thirty 12h and 24h forecasts of atmospheric flow patterns during spring and early summer. The synoptic scale evaluation results benchmark the performance of MASS 2.0 against that of an operational, synoptic scale weather prediction model, the Limited area Fine Mesh (LFM). The large sample allows for the calculation of statistically significant measures of forecast accuracy and the determination of systematic model errors. The synoptic scale benchmark is required before unsmoothed mesoscale forecast fields can be seriously considered.

Koch, S. E.↗
NASA NTRS1985

Results of an observing system simulation experiment based on the proposed Windsat instrument

Two fraternal twin experiments were conducted as part of this study. A data impact experiment using real data (runs 1 and 2) was conducted to assess the impact that rawin wind observations have on both a 5-day assimilation and a single 5-day forecast generated at the end of each assimilation. An observing system simulation experiment (OSSE) using simulated observations (runs 3, 4, and 5) was conducted in order to first calibrate the OSSE results and second to use this calibration to estimate the 'real world' impact from the contribution of global 3-dimensional wind profiles generated from a space-based lidar system known as Windsat. Each of the three runs in the seond experiment were also 5-day assimilation runs with a 5-day forecast initialized from the last 6-hour update cycle of the assimilation. The data impact study revealed a consistent positive impact when rawin winds were added back into an otherwise complete FGGE data set. Both the 6-hour and 5-day forecasts were improved at all levels, in both hemispheres, and for both the wind and the geopotential height fields. Similar results were obtained from the two parallel simulation runs, 3 and 4. Together with the results from runs 1 and 2, calibration coefficients were generated so as to 'correct' the results determined from the addition of Windsat winds (run 5). The Windsat simulation showed a positive improvement in all cases studied. Even though only the tropics were enhanced with these wind observations, hemispheric rms errors were decreased in both the assimilation and 5-day forecast. The 6-hour forecasts of zonal wind from the assimilation run were improved by as much as 50 pct. on the average, and the single forecast showed an average improvement of near 30 pct. Even though these calibrated values are considered too optimistic, the skill of the forecast generated from this run extended the useful forecast period by 18-24 hours.

Arnold, Charles P., Jr.↗
NASA NTRS2024

Observing System Simulation Experiments Exploring Potential Spaceborne Deployment Options for a Differential Absorption Radar Measuring Marine Surface Pressures

A new technology for remote measurements of marine surface pressure has been proposed, employing a V-band differential absorption radar and a radiometric temperature sounder to calculate the total column atmospheric mass. Observing System Simulation Experiments (OSSEs) are performed to evaluate the potential impact of Spaceborne Marine Surface Pressure (SMSP) on Numerical Weather Prediction. These experiments build on prior efforts (Privé, McLinden, et al., 2023, https://doi.org/10.16993/tellusa.3254), but with an updated version of the OSSE framework and with more sophisticated simulation of the SMSP observations and a longer experiment period. Several different instrument configurations are compared, including both scanning and non-scanning orbits. SMSP impacts are calculated for analysis quality and forecast skill, and a forecast sensitivity observation impact tool is employed to place SMSP observations in context with the global observing network. The effects of rain contamination on observation quality are explored. Different magnitudes of simulated SMSP observation error are tested in the context of data assimilation to show the range of potential behaviors. Overall, SMSP observations are found to be most beneficial in the southern hemisphere extratropics, with statistically significant forecast improvements for the first 72 hr of the forecast. A constellation of four non-scanning SMSP satellites is found to outperform a single scanning instrument with a 250 km wide swath.

N C Prive↗
NASA NTRS2020

Evaluation of adjoint-based observation impacts as a function of forecast length using an Observing System Simulation Experiment

Adjoints of numerical weather prediction models may be employed for Forecast Sensitivity to Observation (FSO) in order to monitor the contribution of ingested observation data on short-term forecast skill. However, the calculation of short-term forecast error is difficult due to the lack of a truly independent dataset for verification. In an Observing System Simulation Experiment framework, the Nature Run is able to provide a true and complete verification dataset and allows accurate evaluation of short term forecast errors. In this work, an OSSE developed at the National Aeronautics and Space Administration Global Modeling and Assimilation Office is used to explore the impact of observational data on forecasts in the 6 to 48 hour range. An adjoint of the Global Earth Observing System model is employed to compare the observation impacts estimated using both self-analysis verification and the true Nature Run verification. Self-analysis verification is found to inflate the estimated forecast error growth during the early forecast period, resulting in overestimations of observation impacts, particularly in the 6-12 hour forecast range. By 48 hours, the self-analysis verification estimates of forecast error and observation impacts more closely match the true values. The fraction of beneficial observations is also overinflated at short forecast times when self-analysis verification is used. The progression of impacts of an individual observation or data type depends on the character of the growth of the initial condition error that each observation affects.

numerical weather prediction↗
NASA NTRS1991

Six degree of freedom simulation system for evaluating automated rendezvous and docking spacecraft

Future logistics supply and servicing vehicles such as cargo transfer vehicles (CTV) must have full 6 degree of freedom (6DOF) capability in order to perform requisite rendezvous, proximity operations, and capture operations. The design and performance issues encountered when developing a 6DOF maneuvering spacecraft are very complex with subtle interactions which are not immediately obvious or easily anticipated. In order to deal with these complexities and develop robust maneuvering spacecraft designs, a simulation system and associated family of tools are used at TRW for generating and validating spacecraft performance requirements and guidance algorithms. An overview of the simulator and tools is provided. These are used by TRW for autonomous rendezvous and docking research projects including CTV studies.

Rourke, Kenneth H.↗
NASA NTRS2008

A Modular Aero-Propulsion System Simulation of a Large Commercial Aircraft Engine

A simulation of a commercial engine has been developed in a graphical environment to meet the increasing need across the controls and health management community for a common research and development platform. This paper describes the Commercial Modular Aero Propulsion System Simulation (C-MAPSS), which is representative of a 90,000-lb thrust class two spool, high bypass ratio commercial turbofan engine. A control law resembling the state-of-the-art on board modern aircraft engines is included, consisting of a fan-speed control loop supplemented by relevant engine limit protection regulator loops. The objective of this paper is to provide a top-down overview of the complete engine simulation package.

DeCastro, Jonathan A.↗
NASA NTRS2013

Implementation of Sub-Cooling of Cryogenic Propellants by Injection of Non-condensing Gas to the Generalized Fluid Systems Simulation Program (GFSSP)

Cryogenic propellants are readily heated when used. This poses a problem for rocket engine efficiency and effective boot-strapping of the engine, as seen in the "hot" LOX (Liquid Oxygen) problem on the S-1 stage of the Saturn vehicle. In order to remedy this issue, cryogenic fluids were found to be sub-cooled by injection of a warm non-condensing gas. Experimental results show that the mechanism behind the sub-cooling is evaporative cooling. It has been shown that a sub-cooled temperature difference of approximately 13 deg F below saturation temperature [1]. The phenomenon of sub-cooling of cryogenic propellants by a non-condensing gas is not readily available with the General Fluid System Simulation Program (GFSSP) [2]. GFSSP is a thermal-fluid program used to analyze a wide variety of systems that are directly impacted by thermodynamics and fluid mechanics. In order to model this phenomenon, additional capabilities had to be added to GFSSP in the form of a FORTRAN coded sub-routine to calculate the temperature of the sub-cooled fluid. Once this was accomplished, the sub-routine was implemented to a GFSSP model that was created to replicate an experiment that was conducted to validate the GFSSP results.

Huggett, Daniel J.↗
NASA NTRS2019

Uncertainty of Observation Impact Estimation in an Adjoint Model Investigated with an Observing System Simulation Experiment

Adjoint models are often used to estimate the impact of different observations on short-term forecast skill. A common difficulty with the evaluation of short term forecast quality is the choice of verification fields. The use of self-analysis fields for verification is typical but incestuous, and introduces uncertainty due to biases and errors in the analysis field. In this study, an observing system simulation experiment (OSSE) is used to explore the uncertainty in adjoint model estimations of observation impact. The availability of the true state for verification in the OSSE framework in the form of the Nature Run allows calculation of the observation impact without the uncertainties present in self-analysis verification. These impact estimates are compared to estimates calculated using self-analysis verification. The Global Earth Observing System version 5 (GEOS-5) forecast model with Gridpoint Statistical Interpolation (GSI) is used with the National Aeronautics and Space Administration Global Modeling and Assimilation Office (NASA/GMAO) OSSE capability. The adjoint model includes moist processes, with total wet energy selected as the norm for evaluation of observation impacts. The results show that there are measurable but small discrepancies in the adjoint model estimation of observation impact. In general, observations of temperature and winds tend to have overestimated impacts with self-analysis verification, while observations of humidity and moisture-affected observations tend to have underestimated impacts. The small magnitude of the differences in impact estimates supports the robustness of the adjoint method of estimating observation impacts.

N C Prive↗
NASA NTRS2016

Tool for the Integrated Dynamic Numerical Propulsion System Simulation (NPSS)/Turbine Engine Closed-Loop Transient Analysis (TTECTrA) User's Guide

The Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA ver2) is a control design tool thatenables preliminary estimation of transient performance for models without requiring a full nonlinear controller to bedesigned. The program is compatible with subsonic engine models implemented in the MATLAB/Simulink (TheMathworks, Inc.) environment and Numerical Propulsion System Simulation (NPSS) framework. At a specified flightcondition, TTECTrA will design a closed-loop controller meeting user-defined requirements in a semi or fully automatedfashion. Multiple specifications may be provided, in which case TTECTrA will design one controller for each, producing acollection of controllers in a single run. Each resulting controller contains a setpoint map, a schedule of setpointcontroller gains, and limiters; all contributing to transient characteristics. The goal of the program is to providesteady-state engine designers with more immediate feedback on the transient engine performance earlier in the design cycle.

Transient↗
NASA NTRS1984

Operating system for a real-time multiprocessor propulsion system simulator

The success of the Real Time Multiprocessor Operating System (RTMPOS) in the development and evaluation of experimental hardware and software systems for real time interactive simulation of air breathing propulsion systems was evaluated. The Real Time Multiprocessor Operating System (RTMPOS) provides the user with a versatile, interactive means for loading, running, debugging and obtaining results from a multiprocessor based simulator. A front end processor (FEP) serves as the simulator controller and interface between the user and the simulator. These functions are facilitated by the RTMPOS which resides on the FEP. The RTMPOS acts in conjunction with the FEP's manufacturer supplied disk operating system that provides typical utilities like an assembler, linkage editor, text editor, file handling services, etc. Once a simulation is formulated, the RTMPOS provides for engineering level, run time operations such as loading, modifying and specifying computation flow of programs, simulator mode control, data handling and run time monitoring. Run time monitoring is a powerful feature of RTMPOS that allows the user to record all actions taken during a simulation session and to receive advisories from the simulator via the FEP. The RTMPOS is programmed mainly in PASCAL along with some assembly language routines. The RTMPOS software is easily modified to be applicable to hardware from different manufacturers.

Cole, G. L.↗
NASA NTRS2002

Runway Incursion Prevention System Simulation Evaluation

A Runway Incursion Prevention System (RIPS) was evaluated in a full mission simulation study at the NASA Langley Research center in March 2002. RIPS integrates airborne and ground-based technologies to provide (1) enhanced surface situational awareness to avoid blunders and (2) alerts of runway conflicts in order to prevent runway incidents while also improving operational capability. A series of test runs was conducted in a high fidelity simulator. The purpose of the study was to evaluate the RIPS airborne incursion detection algorithms and associated alerting and airport surface display concepts. Eight commercial airline crews participated as test subjects completing 467 test runs. This paper gives an overview of the RIPS, simulation study, and test results.

Jones, Denise R.↗
NASA NTRS1998

SPARCLE: Validation of Observing System Simulations (SPace Readiness Coherent Lidar Experiment)

NASA recently approved a mission to fly a Doppler Wind Lidar (DWL) on a U.S. Space Shuttle. SPARCLE, managed by Marshall Space Flight Center in Huntsville, AL, is targeted for launch in March 2001. This mission is viewed as a necessary demonstration of a solid state (2 micron) lidar using coherent detection before committing resources to a 3-5 year research or operational mission. While, to many, this shuttle mission is seen as the first step in a series leading to a fully operational wind observing system, to others, it is a chance to validate predictions of performance based upon theoretical models, analyses of airborne and ground-based data, and sophisticated observing system simulation experiments. This paper will be presented in two parts: first a brief overview of the SPARCLE mission and second, a summary of current performance predictions and key contributions from ground- based and airborne DWL research. The SPARCLE instrument is a 100 mJ, 6 Hz, diode-pumped 2-micron laser with a .25 m telescope using heterodyne mixing in a fiber and an InGaAs detector. A 25 cm silicon wedge scanner will be used in step-stare modes with dwells ranging from 60 seconds to .5 seconds. Pointing knowledge is achieved with a dedicated GPS/INS mounted close to the lidar. NASA's Hitchhiker program is providing the instrument enclosures (2 cans) and mission logistics support. An on-board data system is sized to record 150 Gbytes of raw signal from a two 400 MHZ A/D converters. On-board signal processing will be used to control the frequency of the Local Oscillator. SPARCLE is predicted to have a single shot backscatter sensitivity near 1x10(exp -6) m-1 sr-1, To achieve higher sensitivity, shot accumulation will be employed. Ground-based, 2 micron DWLs have been used to assess the benefits of shot accumulation (approximately SQRT for SNR). Airborne programs like MACAWS have provided good datasets for evaluating various sampling strategies and signal processing algorithms. Using these real data to calibrate our simulation models, we can describe when and how well SPARCLE is expected to preform. Outputs from these performance models will be presented.

Emmitt, G. D.↗
NASA NTRSDate not supplied

Lunar Instrument Data Integration Into the Virtual Reality Mission Simulation System for Decision Communication and Situational Awareness

In situ resource utilization (ISRU) technologies are a key advancement required to make human habitation on the Moon and Mars viable. The upcoming Volatiles Investigating Polar Exploration Rover (VIPER) mission will provide crucial correlations between volatiles and lunar geology to understand the water content available for ISRU on the moon. The mission will require the coordination of multi-disciplinary teams across the country making real time decisions based on rover instrument data. The virtual reality Mission Simulation System (vMSS) is a virtual reality platform designed at MIT by the Resource Exploration and Science of our Cosmic Environment (RESOURCE) team to provide teams with a collaboration interface for planetary missions like VIPER. Herein we determine the integration pathway for analog based datasets that are examples of VIPER's two main instruments, the near-infrared volatile spectrometer subsystem (NIRVSS) and the neutron spectrometer subsystem (NSS), into vMSS to provide the most valuable visualization tools. Focusing on improving situational awareness, decision making, reducing task load and incorporating comments from scientists working previous analogs and on the current VIPER mission, we recommend critical elements to implement into vMSS and the best approaches for data visualization. We present a review of relevant analogs and state of the art mission software. We have developed a design concept and path to flight of analysed instrument data integrated with data maps that allow for virtual manipulation and annotation between non-co-located team members. We focus on pre-mission mapping of a priori data for improved situational awareness, layering of analysed instrument data, correlative mapping and interactive capabilities for in-mission decision making, as well as archiving and annotation tools for post-mission analysis. Finally, we lay out the roadmap for the future development of immersive sample site visualization capabilities and the use of integrated instrument data in vMSS with automated temporal and geospatial planning.

Cody Alison Paige↗
NASA NTRS1990

Observing system simulations using synthetic radiances and atmospheric retrievals derived for the AMSU and HIRS in a mesoscale model

The paper addresses the concept of synthetic satellite imagery as a visualization and diagnostic tool for understanding satellite sensors of the future and to detail preliminary results on the quality of soundings from the current sensors. Preliminary results are presented on the quality of soundings from the combination of the High-Resolution Infrared Radiometer Sounder and the Advanced Microwave Sounding Unit. Results are also presented on the first Observing System Simulation Experiment using this data in a mesoscale numerical prediction model.

Diak, George R.↗
NASA NTRSDate not supplied

Modeling of Cryogenic Heated-Tube Flow Boiling Experiments of Nitrogen and Methane with the Generalized Fluid System Simulation Program

Accurate modeling of cryogenic boiling heat transfer is vital for the development of extended-duration space missions. Such missions may require the transfer of cryogenic propellants from in-space storage depots or the cooling of nuclear reactors. Purdue University in collaboration with NASA has assembled a database of cryogenic flow boiling data points from heated-tube experiments dating back to 1959, which has been used to develop new flow boiling correlations specifically for cryogens. Computational models of several of these experiments have been constructed in the Generalized Fluid System Simulation Program (GFSSP), a network flow code developed at NASA’s Marshall Space Flight Center. The new Purdue-developed correlations cover the full boiling curve: onset of nucleate boiling, nucleate boiling, critical heat flux, and film boiling. These correlations have been coded into GFSSP user subroutines. The fluids modeled are methane and nitrogen. Predictions of wall temperature and heat transfer coefficient are presented and compared to the test data.

Multi-Phase Flow↗
NASA NTRSDate not supplied

Modeling of Cryogenic Heated-Tube Flow Boiling Experiments of Hydrogen and Helium With the Generalized Fluid System Simulation Program

Accurate modeling of cryogenic boiling heat transfer is vital for the development of extended-duration space missions. Such missions may require the transfer of cryogenic propellants from in-space storage depots or the cooling of nuclear reactors. Purdue University in collaboration with NASA has assembled a database of cryogenic flow boiling data points from heated-tube experiments dating back to 1959, which has been used to develop new flow boiling correlations specifically for cryogens. Computational models of several of these experiments have been constructed in the Generalized Fluid System Simulation Program (GFSSP), a network flow code developed at NASA’s Marshall Space Flight Center. The new Purdue-developed universal correlations cover the full boiling curve: onset of nucleate boiling, nucleate boiling, critical heat flux, and film boiling. These correlations have been coded into GFSSP user subroutines. The fluids modeled in this study are liquid hydrogen and liquid helium. Predictions of local wall temperature and pressure drop are presented and compared to the test data.

multi-phase flow↗
NASA NTRSDate not supplied

Observing System Simulation Experiments to Determine the Impact of Spaceborne Differential Absorption Radar Measurements of Marine Surface Pressure on Numerical Weather Prediction

Surface air pressures over marine regions can potentially be measured by estimating the total atmospheric column oxygen content with differential absorption radar (DAR). A demonstration instrument, the Microwave Barometric Radar and Sounder (MBARS) has been funded by NASA for airborne missions in 2024 to show proof of concept. In this presentation, the potential use of such marine surface pressure observations from a spaceborne DAR platform to improve numerical weather prediction is examined using the NASA/GMAO global Observing System Simulation Experiment. Several aspects of the instrument are explored, including contamination by heavy precipitation and the expected error characteristics of the observations. Different orbit and scan configurations are compared, including various constellations of nadir smallsats and A-Train-type scanning configurations. The impacts of marine surface pressure observations are put into context with the current global observing network with a Forecast Sensitivity Observation Impact tool.

Nikki Privé↗