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NASA NTRS2010

CECE: Expanding the Envelope of Deep Throttling in Liquid Oxygen/Liquid Hydrogen Rocket Engines For NASA Exploration Missions

As one of the first technology development programs awarded by NASA under the Vision for Space Exploration, the Pratt & Whitney Rocketdyne (PWR) Deep Throttling, Common Extensible Cryogenic Engine (CECE) program was selected by NASA in November 2004 to begin technology development and demonstration toward a deep throttling, cryogenic engine supporting ongoing trade studies for NASA s Lunar Lander descent stage. The CECE program leverages the maturity and previous investment of a flight-proven hydrogen/oxygen expander cycle engine, the PWR RL10, to develop technology and demonstrate an unprecedented combination of reliability, safety, durability, throttlability, and restart capabilities in a high-energy cryogenic engine. The testbed selected for the deep throttling demonstration phases of this program was a minimally modified RL10 engine, allowing for maximum current production engine commonality and extensibility with minimum program cost. Three series of demonstrator engine tests, the first in April-May 2006, the second in March-April 2007 and the third in November-December 2008, have demonstrated up to 13:1 throttling (104% to 8% thrust range) of the hydrogen/oxygen expander cycle engine. The first two test series explored a propellant feed system instability ("chug") environment at low throttled power levels. Lessons learned from these two tests were successfully applied to the third test series, resulting in stable operation throughout the 13:1 throttling range. The first three tests have provided an early demonstration of an enabling cryogenic propulsion concept, accumulating over 5,000 seconds of hot fire time over 27 hot fire tests, and have provided invaluable system-level technology data toward design and development risk mitigation for the NASA Altair and future lander propulsion system applications. This paper describes the results obtained from the highly successful third test series as well as the test objectives and early results obtained from a fourth test series conducted over March-May 2010

Giuliano, Victor J.↗

NASA NTRS2007

CECE: A Deep Throttling Demonstrator Cryogenic Engine for NASA's Lunar Lander

As one of the first technology development programs awarded under NASA's Vision for Space Exploration, the Pratt & Whitney Rocketdyne (PWR) Deep Throttling, Common Extensible Cryogenic Engine (CECE) program was selected by NASA in November 2004 to begin technology development and demonstration toward a deep throttling, cryogenic Lunar Lander engine for use across multiple human and robotic lunar exploration mission segments with extensibility to Mars. The CECE program leverages the maturity and previous investment of a flight-proven hydrogen/oxygen expander cycle engine, the RL10, to develop and demonstrate an unprecedented combination of reliability, safety, durability, throttlability, and restart capabilities in a high-energy, cryogenic engine. NASA Marshall Space Flight Center and NASA Glenn Research Center personnel were integral design and analysis team members throughout the requirements assessment, propellant studies and the deep throttling demonstrator elements of the program. The testbed selected for the initial deep throttling demonstration phase of this program was a minimally modified RL10 engine, allowing for maximum current production engine commonality and extensibility with minimum program cost. In just nine months from technical program start, CECE Demonstrator No. 1 engine testing in April/May 2006 at PWR's E06 test stand successfully demonstrated in excess of 10:1 throttling of the hydrogen/oxygen expander cycle engine. This test provided an early demonstration of a viable, enabling cryogenic propulsion concept with invaluable system-level technology data acquisition toward design and development risk mitigation for both the subsequent CECE Demonstrator No. 2 program and to the future Lunar Lander Design, Development, Test and Evaluation effort.

Giuliano, Victor J.↗

NASA NTRS1990

Evolution of engine cycles for STOVL propulsion concepts

Short Take-off, Vertical Landing (STOVL) demonstrator concepts using a common ATF engine core are discussed. These concepts include a separate fan and core flow engine cycle, mixed flow STOVL cycles, separate flow cycles convertible to mixed flow, and reaction control system engine air bleed. STOVL propulsion controls are discussed.

Bucknell, R. L.↗

NASA NTRS1977

Emissions Reduction Technology Program

Combustor concepts having the potential for significantly lower emissions levels were investigated. The combustor emissions reduction was measured in an engine test. Emission characteristics common to all engine classes are shown. Multiple-burning zone combustors, specifically the double-annular and swirl-can combustors were studied. Airblast and air-assist fuel injection techniques were evaluated for emissions control potential. The combustor sceening and refining phases are summarized.

Jones, R. E.↗

NASA NTRS2018

Bridging the Engineering and Medicine Gap

A primary challenge NASA faces is communication between the disparate entities of engineers and human system experts in life sciences. Clear communication is critical for exploration mission success from the perspective of both risk analysis and data handling. The engineering community uses probabilistic risk assessment (PRA) models to inform their own risk analysis and has extensive experience managing mission data, but does not always fully consider human systems integration (HSI). The medical community, as a part of HSI, has been working 1) to develop a suite of tools to express medical risk in quantitative terms that are relatable to the engineering approaches commonly in use, and 2) to manage and integrate HSI data with engineering data. This talk will review the development of the Integrated Medical Model as an early attempt to bridge the communication gap between the medical and engineering communities in the language of PRA. This will also address data communication between the two entities in the context of data management considerations of the Medical Data Architecture. Lessons learned from these processes will help identify important elements to consider in future communication and integration of these two groups.

Walton, M.↗

NASA NTRS2009

J-2X Upper Stage Engine: Hardware and Testing 2009

Mission: Common upper stage engine for Ares I and Ares V. Challenge: Use proven technology from Saturn X-33, RS-68 to develop the highest Isp GG cycle engine in history for 2 missions in record time . Key Features: LOX/LH2 GG cycle, series turbines (2), HIP-bonded MCC, pneumatic ball-sector valves, on-board engine controller, tube-wall regen nozzle/large passively-cooled nozzle extension, TEG boost/cooling . Development Philosophy: proven hardware, aggressive schedule, early risk reduction, requirements-driven.

Buzzell, James C.↗

NASA NTRSDate not supplied

MBSE Applications for the MSR SRC Mars Ascent Vehicle

The objective of the NASA Mars Sample Return (MSR) Campaign is to collect samples from the surface of Mars and return them to Earth for scientific research. The Mars Ascent Vehicle (MAV) will be integrated into a larger Mars Sample Retrieval Lander (SRL) for transit to and storage on Mars. After all Martian samples have been collected and loaded into the MAV payload assembly, MAV will deliver the samples from the Martian surface to Mars orbit. A separate spacecraft, the Earth Return Orbiter (ERO) will retrieve the samples from Mars orbit and return them to Earth. To address common systems engineering challenges associated with using traditional systems engineering practices on complex projects, the MAV systems engineering team has explored implementation of Model-Based Systems Engineering (MBSE) tools and languages. This paper describes the current state of implementation and development of the MAV MBSE model with the Systems Modeling Language (SysML) within the scope of the MAV Systems Requirement Cycle (SRC) systems engineering workflow. The MAV MBSE model has been developed within Magic Draw – a SysML editor commonly used to implement MBSE. The MAV MBSE model has been used to develop mission phase functional flow diagrams for the Concept of Operations, decompose mission to vehicle subsystem functions, develop a functional decomposition, derive functional requirements, trace requirements up to customer-imposed requirements, trace requirements within MAV requirement space, identify requirements trace gaps, define and map the physical design space architecture, allocate requirements to subsystems, develop validation items, define assembly, integration, and test (AI&T) operations, and trace these items across driving goals to develop an integrated digital thread of systems engineering information used to drive design specifications, decision making, and ultimately design verification and validation. Findings and results associated with implementing MBSE in these ways, alongside traditional methods will be discussed.

MBSE↗

NASA NTRSDate not supplied

MBSE Applications for the MSR SRC Mars Ascent Vehicle

MBSE↗

NASA NTRS1995

Nuclear Thermal Rocket/Vehicle Design Options for Future NASA Missions to the Moon and Mars

The nuclear thermal rocket (NTR) provides a unique propulsion capability to planners/designers of future human exploration missions to the Moon and Mars. In addition to its high specific impulse (approximately 850-1000 s) and engine thrust-to-weight ratio (approximately 3-10), the NTR can also be configured as a 'dual mode' system capable of generating electrical power for spacecraft environmental systems, communications, and enhanced stage operations (e.g., refrigeration for long-term liquid hydrogen storage). At present the Nuclear Propulsion Office (NPO) is examining a variety of mission applications for the NTR ranging from an expendable, single-burn, trans-lunar injection (TLI) stage for NASA's First Lunar Outpost (FLO) mission to all propulsive, multiburn, NTR-powered spacecraft supporting a 'split cargo-piloted sprint' Mars mission architecture. Each application results in a particular set of requirements in areas such as the number of engines and their respective thrust levels, restart capability, fuel operating temperature and lifetime, cryofluid storage, and stage size. Two solid core NTR concepts are examined -- one based on NERVA (Nuclear Engine for Rocket Vehicle Application) derivative reactor (NDR) technology, and a second concept which utilizes a ternary carbide 'twisted ribbon' fuel form developed by the Commonwealth of Independent States (CIS). The NDR and CIS concepts have an established technology database involving significant nuclear testing at or near representative operating conditions. Integrated systems and mission studies indicate that clusters of two to four 15 to 25 klbf NDR or CIS engines are sufficient for most of the lunar and Mars mission scenarios currently under consideration. This paper provides descriptions and performance characteristics for the NDR and CIS concepts, summarizes NASA's First Lunar Outpost and Mars mission scenarios, and describes characteristics for representative cargo and piloted vehicles compatible with a reference 240 t-class heavy lift launch vehicle (HLLV) and smaller 120 t HLLV option. Attractive performance characteristics and high-leverage technologies associated with both the engine and stage are identified, and supporting parametric sensitivity data is provided. The potential for commonality of engine and stage components to satisfy a broad range of lunar and Mars missions is also discussed.

Borowski, Stanley K.↗

NASA NTRS2004

Thermal Load Considerations for Detonative Combustion-Based Gas Turbine Engines

An analysis was conducted to assess methods for, and performance implications of, cooling the passages (tubes) of a pulse detonation-based combustor conceptually installed in the core of a gas turbine engine typical of regional aircraft. Temperature-limited material stress criteria were developed from common-sense engineering practice, and available material properties. Validated, one-dimensional, numerical simulations were then used to explore a variety of cooling methods and establish whether or not they met the established criteria. Simulation output data from successful schemes were averaged and used in a cycle-deck engine simulation in order to assess the impact of the cooling method on overall performance. Results were compared to both a baseline engine equipped with a constant-pressure combustor and to one equipped with an idealized detonative combustor. Major findings indicate that thermal loads in these devices are large, but potentially manageable. However, the impact on performance can be substantial. Nearly one half of the ideally possible specific fuel consumption (SFC) reduction is lost due to cooling of the tubes. Details of the analysis are described, limitations are presented, and implications are discussed.

Paxson, Daniel E.↗

NASA NTRS2005

Heat Transfer and Thermal Stability Research for Advanced Hydrocarbon Fuel Technologies

In recent years there has been increased interest in the development of a new generation of high performance boost rocket engines. These efforts, which will represent a substantial advancement in boost engine technology over that developed for the Space Shuttle Main Engines in the early 1970s, are being pursued both at NASA and the United States Air Force. NASA, under its Space Launch Initiative s Next Generation Launch Technology Program, is investigating the feasibility of developing a highly reliable, long-life, liquid oxygen/kerosene (RP-1) rocket engine for launch vehicles. One of the top technical risks to any engine program employing hydrocarbon fuels is the potential for fuel thermal stability and material compatibility problems to occur under the high-pressure, high-temperature conditions required for regenerative fuel cooling of the engine combustion chamber and nozzle. Decreased heat transfer due to carbon deposits forming on wetted fuel components, corrosion of materials common in engine construction (copper based alloys), and corrosion induced pressure drop increases have all been observed in laboratory tests simulating rocket engine cooling channels. To mitigate these risks, the knowledge of how these fuels behave in high temperature environments must be obtained. Currently, due to the complexity of the physical and chemical process occurring, the only way to accomplish this is empirically. Heated tube testing is a well-established method of experimentally determining the thermal stability and heat transfer characteristics of hydrocarbon fuels. The popularity of this method stems from the low cost incurred in testing when compared to hot fire engine tests, the ability to have greater control over experimental conditions, and the accessibility of the test section, facilitating easy instrumentation. These benefits make heated tube testing the best alternative to hot fire engine testing for thermal stability and heat transfer research. This investigation used the Heated Tube Facility at the NASA Glenn Research Center to perform a thermal stability and heat transfer characterization of RP-1 in an environment simulating that of a high chamber pressure, regenerative cooled rocket engine. The first step in the research was to investigate the carbon deposition process of previous heated tube experiments by performing scanning electron microscopic analysis in conjunction with energy dispersive spectroscopy on the tube sections. This analysis gave insight into the carbon deposition process and the effect that test conditions played in the formation of deleterious coke. Furthermore, several different formations were observed and noted. One other crucial finding of this investigation was that in sulfur containing hydrocarbon fuels, the interaction of the sulfur components with copper based wall materials presented a significant corrosion problem. This problem in many cases was more life limiting than those posed by the carbon deposition process. The results of this microscopic analysis was detailed and presented at the December 2003 JANNAF Air-Breathing Propulsion Meeting as a Materials Compatibility and Thermal Stability Analysis of common Hydrocarbon Fuels (reference 1).

DeWitt, Kenneth↗

NASA NTRS2021

A Guide for Aircraft Certification by Analysis

Analysis-based means of compliance for airplane and engine certification, commonly known as "Certification by Analysis" (CbA), provides a strong motivation for the development and maturation of current and future flight and engine modeling technology. The many benefits of CbA include streamlined product certification testing programs at lower cost while maintaining equivalent levels of safety. Flight and engine testing represent a substantial cost to airplane and engine development programs. This report provides a far-reaching vision for CbA and presents a research roadmap for computational technology development to enable CbA.

certification by analysis↗

NASA NTRS2007

Noise Reduction Technologies for Turbofan Engines

Significant progress continues to be made with noise reduction for turbofan engines. NASA has conducted and sponsored research aimed at reducing noise from commercial aircraft. Since it takes many years for technologies to be developed and implemented, it is important to have aggressive technology goals that lead the target entry into service dates. Engine noise is one of the major contributors to the overall sound levels as aircraft operate near airports. Turbofan engines are commonly used on commercial transports due to their advantage for higher performance and lower noise. The noise reduction comes from combinations of changes to the engine cycle parameters and low noise design features. In this paper, an overview of major accomplishments from recent NASA research programs for engine noise will be given.

Huff, Dennis L.↗

NASA NTRS1993

Open environments to support systems engineering tool integration: A study using the Portable Common Tool Environment (PCTE)

A study of computer engineering tool integration using the Portable Common Tool Environment (PCTE) Public Interface Standard is presented. Over a 10-week time frame, three existing software products were encapsulated to work in the Emeraude environment, an implementation of the PCTE version 1.5 standard. The software products used were a computer-aided software engineering (CASE) design tool, a software reuse tool, and a computer architecture design and analysis tool. The tool set was then demonstrated to work in a coordinated design process in the Emeraude environment. The project and the features of PCTE used are described, experience with the use of Emeraude environment over the project time frame is summarized, and several related areas for future research are summarized.

Eckhardt, Dave E., Jr.↗

NASA NTRS2003

Comparison of Acoustic Impedance Eduction Techniques for Locally-Reacting Liners

Typical acoustic liners used in current aircraft inlets and aft-fan ducts consist of some type of perforated facesheet bonded to a honeycomb core. A number of techniques for determining the acoustic impedance of these locallyreacting liners have been developed over the last five decades. In addition, a number of models have been developed to predict the acoustic impedance of locallyreacting liners in the presence of grazing flow, and to use that information together with aeroacoustic propagation codes to assess the noise absorption provided by these liners. These prediction models have incorporated the results from databases acquired with specific impedance eduction techniques. Thus, while these prediction models are acceptable for liners that are similar to those tested in these databases, their application to new liner configurations must be viewed with caution. The primary purpose of this paper is to provide a comparison of impedance eduction techniques that have been implemented at various aerospace research laboratories in the United States (NASA Langley Research Center, General Electric Aircraft Engines, B. F. Goodrich and Boeing). A secondary purpose is to provide data for liner configurations that extend the porosity range beyond that which has been previously used in common aircraft engine nacelles. Two sets of liners were designed to study the effects of three parameters: perforate hole diameter, facesheet thickness and porosity. These two sets of liners were constructed for testing in each of the laboratories listed above. The first set of liners was designed to fit into the NASA Langley and Boeing test facilities. The second set was designed to fit into the General Electric Aircraft Engines and B. F. Goodrich test facilities. By using the same parent material, both sets of liners were identical to within the limits of material and fabrication variability. Baseline data were obtained in the normal incidence impedance tubes at NASA Langley and B. F. Goodrich. The results were found to compare extremely well. The samples were then tested in the grazing flow ducts of each of the four laboratories. Perhaps the most significant result of these comparisons is that the educed acoustic resistances for the liners used in this study increase as the mean flow profile is modified from uniform to 3-D shear. This realization has demonstrated the need for an frequency-dependent impedance eduction technique that incorporates 3-D shear flow and is efficient.

Jones, M. G.↗

NASA NTRS2004

Hybrid Automotive Engine Using Ethanol-Burning Miller Cycle

A proposed hybrid (internal-combustion/ electric) automotive engine system would include as its internal-combustion subsystem, a modified Miller-cycle engine with regenerative air preheating and with autoignition like that of a Diesel engine. The fuel would be ethanol and would be burned lean to ensure complete combustion. Although the proposed engine would have a relatively low power-to-weight ratio compared to most present engines, this would not be the problem encountered if this engine were used in a non-hybrid system since hybrid systems require significantly lower power and thus smaller engines than purely internal-combustion-engine-driven vehicles. The disadvantage would be offset by the advantages of high fuel efficiency, low emission of nitrogen oxides and particulate pollutants, and the fact that ethanol is a renewable fuel. The original Miller-cycle engine, named after its inventor, was patented in the 1940s and is the basis of engines used in some modern automobiles, but is not widely known. In somewhat oversimplified terms, the main difference between a Miller-cycle engine and a common (Otto-cycle) automobile engine is that the Miller-cycle engine has a longer expansion stroke while retaining the shorter compression stroke. This is accomplished by leaving the intake valve open for part of the compression stroke, whereas in the Otto cycle engine, the intake valve is kept closed during the entire compression stroke. This greater expansion ratio makes it possible to extract more energy from the combustion process without expending more energy for compression. The net result is greater efficiency. In the proposed engine, the regenerative preheating would be effected by running the intake air through a heat exchanger connected to the engine block. The regenerative preheating would offer two advantages: It would ensure reliable autoignition during operation at low ambient temperature and would help to cool the engine, thereby reducing the remainder of the power needed for cooling and thereby further contributing to efficiency. An electrical resistance air preheater might be needed to ensure autoignition at startup and during a short warmup period. Because of the autoignition, the engine could operate without either spark plugs or glow plugs. Ethanol burns relatively cleanly and has been used as a motor fuel since the invention of internal-combustion engines. However, the energy content of ethanol per unit weight of ethanol is less than that of Diesel fuel or gasoline, and ethanol has a higher heat of vaporization. Because the Miller cycle offers an efficiency close to that of the Diesel cycle, burning ethanol in a Miller-cycle engine gives about as much usable output energy per unit volume of fuel as does burning gasoline in a conventional gasoline automotive engine. Because of the combination of preheating, running lean, and the use of ethyl alcohol, the proposed engine would generate less power per unit volume than does a conventional automotive gasoline engine. Consequently, for a given power level, the main body of the proposed engine would be bulkier. However, because little or no exhaust cleanup would be needed, the increase in bulk of the engine could be partially offset by the decrease in bulk of the exhaust system. The regenerative preheating also greatly reduces the external engine cooling requirement, and would translate to reduced engine bulk. It may even be possible to accomplish the remaining cooling of the engine by use of air only, eliminating the bulk and power consumption of a water cooling system. The combination of a Miller-cycle engine with regenerative air preheating, ethyl alcohol fuel, and hybrid operation could result in an automotive engine system that satisfies the need for a low pollution, high efficiency, and simple engine with a totally renewable fuel.

Weinstein, Leonard↗

NASA NTRS2016

Expanded Guidance for NASA Systems Engineering. Volume 2: Crosscutting Topics, Special Topics, and Appendices

Historically, most successful NASA projects have depended on effectively blending project management, systems engineering, and technical expertise among NASA, contractors, and third parties. Underlying these successes are a variety of agreements (e.g., contract, memorandum of understanding, grant, cooperative agreement) between NASA organizations or between NASA and other Government agencies, Government organizations, companies, universities, research laboratories, and so on. To simplify the discussions, the term "contract" is used to encompass these agreements. This section focuses on the NASA systems engineering activities pertinent to awarding a contract, managing contract performance, and completing a contract. In particular, NASA systems engineering interfaces to the procurement process are covered, since the NASA engineering technical team plays a key role in the development and evaluation of contract documentation. Contractors and third parties perform activities that supplement (or substitute for) the NASA project technical team accomplishment of the NASA common systems engineering technical process activities and requirements outlined in this guide. Since contractors might be involved in any part of the systems engineering life cycle, the NASA project technical team needs to know how to prepare for, allocate or perform, and implement surveillance of technical activities that are allocated to contractors.

Steven R Hirshorn↗

NASA NTRS1978

A survey of electric and hybrid vehicle simulation programs

Results of a survey conducted within the United States to determine the extent of development and capabilities of automotive performance simulation programs suitable for electric and hybrid vehicle studies are summarized. Altogether, 111 programs were identified as being in a usable state. The complexity of the existing programs spans a range from a page of simple desktop calculator instructions to 300,000 lines of a high-level programming language. The capability to simulate electric vehicles was most common, heat-engines second, and hybrid vehicles least common. Batch-operated programs are slightly more common than interactive ones, and one-third can be operated in either mode. The most commonly used language was FORTRAN, the language typically used by engineers. The higher-level simulation languages (e.g. SIMSCRIPT, GPSS, SIMULA) used by "model builders" were conspicuously lacking.

Bevan, J.↗