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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Space Shuttle Main Engine (SSME) Pogo testing and results

To effectively assess the Pogo stability of the space shuttle vehicle, it was necessary to characterize the structural, propellant, and propulsion dynamics subsystems. Extensive analyses and comprehensive testing programs were established early in the project as an implementation of management philosophy of Pogo prevention for space shuttle. The role of the space shuttle main engine (SSMF) in the Pogo prevention plans, the results obtained from engine ground testing with analysis, and measured data from STS-1 flight are discussed.

Fenwick, J. R.↗
NASA NTRS1987

Thermodynamic analysis and subscale modeling of space-based orbit transfer vehicle cryogenic propellant resupply

The resupply of the cryogenic propellants is an enabling technology for spacebased orbit transfer vehicles. As part of the NASA Lewis ongoing efforts in microgravity fluid management, thermodynamic analysis and subscale modeling techniques were developed to support an on-orbit test bed for cryogenic fluid management technologies. Analytical results have shown that subscale experimental modeling of liquid resupply can be used to validate analytical models when the appropriate target temperature is selected to relate the model to its prototype system. Further analyses were used to develop a thermodynamic model of the tank chilldown process which is required prior to the no-vent fill operation. These efforts were incorporated into two FORTRAN programs which were used to present preliminary analyticl results.

Defelice, David M.↗
NASA NTRS1986

Thermodynamic analysis and subscale modeling of space-based orbit transfer vehicle cryogenic propellant resupply

The resupply of the cryogenic propellants is an enabling technology for spacebased orbit transfer vehicles. As part of the NASA Lewis ongoing efforts in microgravity fluid management, thermodynamic analysis and subscale modeling techniques were developed to support an on-orbit test bed for cryogenic fluid management technologies. Analytical results have shown that subscale experimental modeling of liquid resupply can be used to validate analytical models when the appropriate target temperature is selected to relate the model to its prototype system. Further analyses were used to develop a thermodynamic model of the tank chilldown process which is required prior to the no-vent fill operation. These efforts were incorporated into two FORTRAN programs which were used to present preliminary analytical results.

Defelice, David M.↗
NASA NTRS2005

Key Reliability Drivers of Liquid Propulsion Engines and A Reliability Model for Sensitivity Analysis

This paper is to address the in-flight reliability of a liquid propulsion engine system for a launch vehicle. We first establish a comprehensive list of system and sub-system reliability drivers for any liquid propulsion engine system. We then build a reliability model to parametrically analyze the impact of some reliability parameters. We present sensitivity analysis results for a selected subset of the key reliability drivers using the model. Reliability drivers identified include: number of engines for the liquid propulsion stage, single engine total reliability, engine operation duration, engine thrust size, reusability, engine de-rating or up-rating, engine-out design (including engine-out switching reliability, catastrophic fraction, preventable failure fraction, unnecessary shutdown fraction), propellant specific hazards, engine start and cutoff transient hazards, engine combustion cycles, vehicle and engine interface and interaction hazards, engine health management system, engine modification, engine ground start hold down with launch commit criteria, engine altitude start (1 in. start), Multiple altitude restart (less than 1 restart), component, subsystem and system design, manufacturing/ground operation support/pre and post flight check outs and inspection, extensiveness of the development program. We present some sensitivity analysis results for the following subset of the drivers: number of engines for the propulsion stage, single engine total reliability, engine operation duration, engine de-rating or up-rating requirements, engine-out design, catastrophic fraction, preventable failure fraction, unnecessary shutdown fraction, and engine health management system implementation (basic redlines and more advanced health management systems).

Huang, Zhao-Feng↗
NASA NTRS2010

Cryogenic Fluid Management Technology for Moon and Mars Missions

In support of the U.S. Space Exploration Policy, focused cryogenic fluid management technology efforts are underway within the National Aeronautics and Space Administration. Under the auspices of the Exploration Technology Development Program, cryogenic fluid management technology efforts are being conducted by the Cryogenic Fluid Management Project. Cryogenic Fluid Management Project objectives are to develop storage, transfer, and handling technologies for cryogens to support high performance demands of lunar, and ultimately, Mars missions in the application areas of propulsion, surface systems, and Earth-based ground operations. The targeted use of cryogens and cryogenic technologies for these application areas is anticipated to significantly reduce propellant launch mass and required on-orbit margins, to reduce and even eliminate storage tank boil-off losses for long term missions, to economize ground pad storage and transfer operations, and to expand operational and architectural operations at destination. This paper organizes Cryogenic Fluid Management Project technology efforts according to Exploration Architecture target areas, and discusses the scope of trade studies, analytical modeling, and test efforts presently underway, as well as future plans, to address those target areas. The target areas are: liquid methane/liquid oxygen for propelling the Altair Lander Ascent Stage, liquid hydrogen/liquid oxygen for propelling the Altair Lander Descent Stage and Ares V Earth Departure Stage, liquefaction, zero boil-off, and propellant scavenging for Lunar Surface Systems, cold helium and zero boil-off technologies for Earth-Based Ground Operations, and architecture definition studies for long term storage and on-orbit transfer and pressurization of LH2, cryogenic Mars landing and ascent vehicles, and cryogenic production via in situ resource utilization on Mars.

Doherty, Michael P.↗
NASA NTRS1993

Engine management during NTRE start up

The topics are presented in viewgraph form and include the following: total engine system management critical to successful nuclear thermal rocket engine (NTRE) start up; NERVA type engine start windows; reactor power control; heterogeneous reactor cooling; propellant feed system dynamics; integrated NTRE start sequence; moderator cooling loop and efficient NTRE starting; analytical simulation and low risk engine development; accurate simulation through dynamic coupling of physical processes; and integrated NTRE and mission performance.

Bulman, Mel↗
NASA NTRS2013

Cryogenics Research and Engineering Experience

Energy efficient storage, transfer and use of cryogens and cryogenic propellants on Earth and in space have a direct impact on NASA, government and commercial programs. Research and development on thermal insulation, propellant servicing, cryogenic components, material properties and sensing technologies provides industry, government and research institutions with the cross-cutting technologies to manage low-temperature applications. Under the direction of the Cryogenic Testing Lab at Kennedy Space Center, the work experience acquired allowed me to perform research, testing, design and analysis of current and future cryogenic technologies to be applied in several projects.

Toro Medina, Jaime A.↗
NASA NTRS2018

Creating a Voyager Thermal Model 39 Years Into the Flight Mission, Along with Model Correlation and Application

After 39 years of continuous operation in space, the output of the Voyager 1 & 2 spacecraft RTG power systems has decreased to the point where managing the power margin and maintaining thermal control has become increasingly difficult. As the total power dissipation in the bus has decreased, propellant line temperatures and margin above minimum AFTs have decreased, creating risk of the hydrazine freezing (at 1.6°C). This is further complicated by the lack of existing thermal models that can be used to assess propellant tank and line temperatures. In 2014, an effort was begun to create a Voyager spacecraft thermal model for that purpose.A steady-state Thermal Desktop model has been created from scratch over the past two years. The initial thermal model development was started by Applied Sciences Laboratory (ASL) under contract to JPL. The effort relied primarily on archived manufacturing drawings, limited documentation, interviews of senior engineers who worked on the Voyager design and implementation, and the experience of the Voyager Flight Operations team.Data from the Voyager System Thermal Vacuum tests is no longer available, making it necessary to correlate the model to more recent flight data and small in-flight tests. Correlation was achieved to within ±5°C for a hot case and a cold case (both data sets from 2014). However, the flight system has very few temperature sensors directly on propellant lines. So the task remains to determine how best to use the model, in conjunction with flight data, to make sure the Voyagers can continue to fly successfully. How does one go about creating a thermal model for a spacecraft that is already launched, has limited existing mechanical description files, no thermal model in order to do a maneuver that was never planned when the spacecraft was designed?

Ledeboer, William C.↗
NASA NTRS2018

Creating a Voyager Thermal Model 39 Years Into the Flight Mission, Along With Model Correlation and Application

After 39 years of continuous operation in space, the output of the Voyager 1 & 2 spacecraft Radioisotope Thermoelectric Generator (RTG) power systems has decreased to the point where managing the power margin and maintaining thermal control has become increasingly difficult. As the total power dissipation in the bus has decreased, propellant line temperatures and margin above minimum Allowable Flight Temperature (AFT) have decreased, creating risk of the hydrazine freezing (at 1.6°C). This is further complicated by the lack of existing thermal models that can be used to assess propellant tank and line temperatures. In 2014, an effort was begun to create a Voyager spacecraft thermal model for that purpose. A steady-state Thermal Desktop model has been created from scratch over the past two years. Applied Sciences Laboratory (ASL) started the initial thermal model development under contract to Jet Propulsion Laboratory (JPL). The effort relied primarily on archived manufacturing drawings, limited documentation, interviews of senior engineers who worked on the Voyager design and implementation, and the experience of the Voyager Flight Operations team. Data from the Voyager System Thermal Vacuum (STV) tests is no longer available, making it necessary to correlate the model to more recent flight data and small in-flight tests. Correlation was achieved to within ±5°C for a hot case and a cold case (both data sets from 2014). However, the flight system has very few temperature sensors directly on propellant lines. Therefore, the task remains to determine how best to use the model, in conjunction with flight data, to make sure the Voyagers can continue to fly successfully.

Ledeboer, William C.↗
NASA NTRS1992

Gravity jitter induced slosh waves in liquid propellant and disturbances of fluid stresses on spacecraft

The paper investigates the dynamical behavior of fluids, in particular the effect of surface tension on partially filled rotating fluids (cryogenic liquid helium and helium vapor) in a full-scale Gravity Probe-B spacecraft propellant dewar tank imposed by various frequencies of gravity jitters. Fluid stress distribution caused by the excitation of slosh waves and their associated large amplitude disturbances on the liquid-vapor interface and exerted on the outer and inner walls of a rotating dewar container are also examined. It is shown that fluid stress distributions near the outer and inner walls of the rotating dewar are closely related to the characteristics of slosh waves excited in the liquid-vapor interface in the rotating dewar tank. This can be of utility in managing spacecraft dynamic control leading to control of spacecraft imbalance caused by the uneven fluid stress distribution due to slosh wave excitations at the interface between liquid and vapor propellants.

Hung, R. J.↗
NASA NTRS1985

Training managers for high productivity: Guidelines and a case history

Hughes Aircrafts 13-year productivity study clearly identifies management as the key link in the entire productivity chain. This fact led to the establishment of a long-term series of seminars on personal, managerial, organizational, and operational productivity for all levels and sectors of line and staff management. To inspire the work force to higher levels of productivity and creativity management, itself, must first be inspired. In turn they have to clearly understand the productive and creative processes, fashion an effective productivity improvement plan with sound strategy and implementation, create an optimal environmental chemistry, and provide the outstanding leadership necessary to propel their organizations to achieve full potential. The primary goals of the seminars are to (1) ignite that spark of inspiration, enabling productive action to follow, (2) provide participants a credible roadmap and effective tools for implementation, and (3) develop a dedicated commitment to leadership and productivity throughout the management team.

Ranftl, R. M.↗
NASA NTRS1992

Spacecraft dynamical distribution of fluid stresses activated by gravity-jitter-induced slosh waves

The dynamical behavior of fluids, in particular the effect of surface tension on partially filled rotating fluids (cryogenic liquid helium and helium vapor) in a full-scale Gravity Probe-B Spacecraft propellant Dewar tank imposed by various frequencies of gravity jitters, has been investigated. Fluid stress distribution, caused by the excitation of slosh waves and their associated large-amplitude disturbances on the liquid-vapor interface, exerted on the outer and inner walls of a rotating Dewar container also has been investigated. Results show that fluid stress distributions near the outer and inner walls of the rotating Dewar are closely related to the characteristics of slosh waves excited on the liquid-vapor interface in the rotating Dewar tank. This can provide a useful tool for managing spacecraft dynamic control leading toward the control of spacecraft imbalance caused by the uneven fluid stress distribution due to slosh wave excitations at the interface between liquid and vapor propellants.

Hung, R. J.↗
DOE OSTI2025

Fuel cells for single-aisle regional aircraft: System configuration, performance and cost

A hydrogen fuel cell propelled electric aircraft can compete with incumbent turbofan technologies for single-aisle regional aircraft by coupling design of stack, air handling, thermal management, propulsion, and airframe to optimize performance. The stack operates at 95°C to facilitate heat rejection during take-off and below 75°C during cruise to extend lifetime and is oversized to satisfy power requirements at end of life. A multi-stage turbocompressor with a compression ratio >10 is selected to reach high stack power density at 11,300-m cruise altitude. The propulsion system is configured to accommodate air handling within the core duct, an inclined heat exchanger in the outer duct to limit the nacelle size, and variable area nozzles to independently control mass flows through the core and bypass ducts. The airframe is modified for maximum lift coefficient and longer balanced field length for dramatically reduced thrust during take-off, and the fuselage is stretched by 20% to store liquid hydrogen (LH 2 ). Modularization of power systems promotes safety in one engine inoperative scenarios and allows reaching specific power metrics for stack, balance-of-plant and fuel cell system (FCS), necessary for acceptable take-off weight. In conclusion, cost parity requires increase in FCS lifetime, LH 2 cost reduction, and improved FCS specific power.

Catalyst durability↗
NASA NTRS1984

Motor Controllers

Kollmorgen Corporation's Mermaid II two person submersible is propeller-driven by a system of five DC brushless motors with new electronic controllers that originated in work performed in a NASA/DOE project managed by Lewis Research Center. A key feature of the system is electric commutation rather than mechanical commutation for converting AC current to DC.

Source record↗
NASA NTRSDate not supplied

Comparison of Acoustic Models and Trajectory Generation Methods for an Acoustically-Aware Aircraft

Motivation - Noise management is one of the major barriers to Urban Air Mobility - Approaches to noise mitigation (non-exhaustive) - Vehicle configuration - Directivity control via propeller phase synchronization - Trajectory optimization Objective - Create framework for trajectory generation integrating location-based acoustic metrics and vehicle performance limitations - Multiple trajectory optimization methods and acoustic noise models - Mission-relevant constraints - Mission duration, airspace restrictions, ... - Vehicle dynamic constraints - Aircraft structural limitations, min/max airspeed, ... - Vehicle separation/obstacle avoidance - Acoustic constraints at a number of discrete observer locations

Kasey A. Ackerman↗
NASA NTRSDate not supplied

Comparison of Acoustic Models and Trajectory Generation Methods for an Acoustically-Aware Aircraft

Motivation - Noise management is one of the major barriers to Urban Air Mobility - Approaches to noise mitigation (non-exhaustive) - Vehicle configuration - Directivity control via propeller phase synchronization - Trajectory optimization Objective - Create framework for trajectory generation integrating location-based acoustic metrics and vehicle performance limitations - Multiple trajectory optimization methods and acoustic noise models - Mission-relevant constraints - Mission duration, airspace restrictions, ... - Vehicle dynamic constraints - Aircraft structural limitations, min/max airspeed, ... - Vehicle separation/obstacle avoidance - Acoustic constraints at a number of discrete observer locations

Kasey A Ackerman↗
DOE OSTI2022

Initial Atmospheric Transport (IAT)

SAND2022-12904 O Initial Atmospheric Transport (IAT) predicts the initial puff/plume rise resulting from either a solid rocket propellant or liquid rocket fuel fire. The code generates initial conditions for subsequent atmospheric transport calculations. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Villa, Daniel↗