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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Hot Wax Sweeps Debris From Narrow Passages

Safe and effective technique for removal of debris and contaminants from narrow passages involves entrainment of undesired material in thermoplastic casting material. Semisolid wax slightly below melting temperature pushed along passage by pressurized nitrogen to remove debris. Devised to clean out fuel passages in main combustion chamber of Space Shuttle main engine. Also applied to narrow, intricate passages in internal-combustion-engine blocks, carburetors, injection molds, and other complicated parts.

Ricklefs, Steven K.↗
NASA NTRS1996

Dual Spark Plugs For Stratified-Charge Rotary Engine

Fuel efficiency of stratified-charge, rotary, internal-combustion engine increased by improved design featuring dual spark plugs. Second spark plug ignites fuel on upstream side of main fuel injector; enabling faster burning and more nearly complete utilization of fuel.

Abraham, John↗
DOE OSTI2026

Substitution or Shared Utilization? Intrahousehold Vehicle Use in Mixed-Powertrain Households

While previous research has focused heavily on understanding the factors deriving alternative fuel vehicle adoption rates, there remains a significant gap in understanding how households distribute mileage across different powertrains. This study utilizes data from the 2022 Next Generation National Household Travel Survey to investigate vehicle miles traveled within a sample of 150 plug-in electric vehicle (PEV)-owning households (in which at least one battery electric vehicle is present), characterizing how different powertrains are integrated into daily mobility. Leveraging a Seemingly Unrelated Regression (SUR) framework the study jointly models the utilization of PEVs, hybrid electric vehicles (HEV), and internal combustion engine vehicles (ICEVs) while accounting for household-level substitution effects. The results provide evidence of an asymmetric substitution effect. In households with mixed-powertrain configurations, the ICEV captures a substantially higher share of household miles (compared with the PEV), acting as a utility sponge. Conversely, the model identifies specific socioeconomic and geographic cohorts that prioritize PEV as the primary household workhorse, indicating a systematic sorting effect. Although the sample size limits broader generalizability, these findings suggest that PEVs are used for frequent, specific routine-intensive roles, whereas the ICEV remains a specialized utility vehicle. These insights highlight distinct intrahousehold vehicle use behaviors that are often obscured by aggregate fleetwide statistics.

25 ENERGY STORAGE↗
NASA NTRS1993

Kalman-Filter Estimation Of Unmeasured Output Variables

Kalman-filter "observer" algorithm used in estimating unmeasured output variables of turbofan engine. Unmeasured output variables needed along with measured output variables as feedback data to characterize state of aircraft-and-engine system for control purposes. Subsystem or processor implementing Kalman-filter algorithm incorporated into adaptive digital control system, called "performance-seeking" control system, developed to compute engine-control settings to optimize performance of aircraft under given pseudo-steady-state cruise conditions. Basic concept of algorithm not restricted to aircraft-engine application and can be extended to internal-combustion engines in land vehicles.

Gilyard, Glenn B.↗
NASA NTRS1926

On the knocking of gasoline engines

It is of the greatest importance, not only for automobile engines, but also for every other kind of internal combustion engine, since it limits the degree of compression and the thermal efficiency and its investigation indicates ways for saving fuel.

DETONATION↗
NASA NTRS1998

Carbon-Carbon Turbocharger Housing Unit for Intermittent Combustion Engines

An improved, lightweight, turbine housing unit for an intermittent combustion reciprocating internal combustion engine turbocharger is prepared from a lay-up or molding of carbon-carbon composite materials in a single-piece or two-piece process. When compared to conventional steel or cast iron, the use of carbon-carbon composite materials in a turbine housing unit reduces the overall weight of the engine and reduces the heat energy loss used in the turbocharging process. This reduction in heat energy loss and weight reduction provides for more efficient engine operation.

Northam, G. Burton↗
NASA NTRS1999

Process for Making Carbon-Carbon Turbocharger Housing Unit for Intermittent Combustion Engines

An improved. lightweight, turbine housing unit for an intermittent combustion reciprocating internal combustion engine turbocharger is prepared from a lay-up or molding of carbon-carbon composite materials in a single-piece or two-piece process. When compared to conventional steel or cast iron, the use of carbon-carbon composite materials in a turbine housing unit reduces the overall weight of the engine and reduces the heat energy loss used in the turbo-charging process. This reduction in heat energy loss and weight reduction provides for more efficient engine operation.

Northam, G. Burton↗
NASA NTRS1996

Self-Lubricating, Wear-Resistant Diamond Films Developed for Use in Vacuum Environment

Diamond's outstanding properties--extreme hardness, chemical and thermal inertness, and high strength and rigidity--make it an ideal material for many tribological applications, such as the bearings, valves, and engine parts in the harsh environment found in internal-combustion engines, jet engines, and space propulsion systems. It has been demonstrated that chemical-vapor-deposited diamond films have low coefficients of friction (on the order of 0.01) and low wear rates (less than 10(sup -7) mm (sup 3/N-m)) both in humid air and dry nitrogen but that they have both high coefficients of friction (greater than 0.4) and high wear rates (on the order of 1(sup -4) mm sup 3/N-m)) in vacuum. It is clear that surface modifications that provide acceptable levels of friction and wear properties will be necessary before diamond films can be used for tribological applications in a space-like, vacuum environment. Previously, it was found that coatings of amorphous, non-diamond carbon can provide low friction in vacuum. Therefore, to reduce the friction and wear of diamond film in vacuum, carbon ions were implanted in an attempt to form a surface layer of amorphous carbon phases on the diamond films.

Source record↗
NASA NTRS1986

Alloy chemistry and microstructural control to meet the demands of the automotive Stirling engine

The automotive Stirling engine now under development by DOE/NASA as an alternative to the internal combustion engine, imposes severe materials requirements for the hot portion of the engine. Materials selected must be low cost and contain a minimum of strategic elements so that availability is not a problem. Heater head tubes contain high pressure hydrogen on the inside and are exposed to hot combustion gases on the outside surface. The cylinders and regenerator housings must be readily castable into complex shapes having varying wall thicknesses and be amenable to brazing and welding operations. Also, high strength, oxidation resistance, resistance to hydrogen permeation, cyclic operation, and long-life are required. A research program conducted by NASA Lewis focused on alloy chemistry and microstructural control to achieve the desired properties over the life of the engine. Results of alloy selection, characterization, evaluation, and actual engine testing of selected materials are presented.

Stephens, J. R.↗
NASA NTRS1988

Alloy chemistry and microstructural control to meet the demands of the automotive Stirling engine

The automotive Stirling engine now under development by DOE/NASA as an alternative to the internal combustion engine, imposes severe materials requirements for the hot portion of the engine. Materials selected must be low cost and contain a minimum of strategic elements so that availability is not a problem. Heater head tubes contain high pressure hydrogen on the inside and are exposed to hot combustion gases on the outside surface. The cylinders and regenerator housings must be readily castable into complex shapes having varying wall thicknesses and be amenable to brazing and welding operations. Also, high strength, oxidation resistance, resistance to hydrogen permeation, cyclic operation, and long-life are required. A research program conducted by NASA Lewis focused on alloy chemistry and microstructural control to achieve the desired properties over the life of the engine. Results of alloy selection, characterization, evaluation, and actual engine testing of selected materials are presented.

Stephens, Joseph R.↗
DOE OSTI2024

Improving Efficiency of Off-Road Vehicles by Novel Integration of Electric Machines and Advanced Combustion Engines

Modern off-road equipment will increasingly rely on electrified implements that will deliver precision control with a smaller footprint than hydraulics. The primary energy converter, however, will be an onboard reciprocating internal combustion engine because of the power density of hydrocarbon fuels in comparison to electrical energy storage and the remote locations where much of this equipment is deployed. Adding energy storage and electric machines creates opportunities to improve efficiency while reducing emissions. This program investigated approaches to take advantage of the extra flexibility that an enhanced electrical system to enable high-efficiency, low-emissions combustion technologies. The current program evaluated hybridization of both the torque application and air-handling systems to maximize efficiency while minimizing cost. This program designed, analyzed and tested a hybrid off-road vehicle consisting of a series electric powertrain with energy storage, an electrified air system, and a 33% downsized diesel engine. Detailed comparisons were made between the base powertrain and the developed powertrain using powertrain simulations, engine testing, and vehicle testing. The key results of the study are: • The resulting vehicle reduces fuel consumption by 5% to 15% at equal productivity. The primary improvements were due to recovery of regenerative braking losses for cycles where large transients are encountered. • The electrified air system was an enabler to allow engine downsizing. This was most important for duty-cycles where the engine primarily operated at moderate loads and had few low speed high torque conditions. • Engine level improvements showed re-optimization of the powertrain is possible when electrified air handing is available. Increased exhaust gas recirculation and advanced injection timing allowed up to a 15% reduction in brake specific fuel consumption at equal NOx and transient response. Compared to the larger engine, the downsized engine achieves up to an 18% reduction in brake specific fuel consumption over the non-road transient cycle. • The life cycle analysis and total cost of ownership study showed that the hybrid powertrain has the potential to reduce 5-year CO2 and total cost of ownership by ~6% over the baseline vehicle. The results also indicated that a pure battery electric vehicle is not feasible in this application and is likely to increase the CO2 emissions due to the CO2 from battery production. A hybrid powertrain with low carbon fuels shows the potential to substantially reduce CO2 and total cost of ownership.

02 PETROLEUM↗
DOE OSTI2025

Effect of CO on alcohol oxidation over commercial oxidation catalysts for control of emissions from lean-burn engines

For commercialization, alcohol-based net-zero carbon fuels in diesel-driven internal combustion engines must meet emissions standards set by the U.S. Environmental Protection Agency. Here, a series of aged commercial oxidation catalysts, Pt diesel oxidation catalyst (DOC), Pd+Pt DOC, and Pt oxidation catalyst (Pt OC), were studied using an automated flow reactor and in situ DRIFTS techniques to investigate the impact of CO on alcohol oxidation. Surface formate and acetate intermediates were formed due to partial oxidation of methanol and ethanol, respectively. Sequential introduction of alcohol and CO experiments using in situ DRIFTS on all three catalysts showed that CO inhibited low temperature methanol oxidation. Mutual inhibition effects between CO and ethanol were observed during co-oxidation. Acetate species shifted CO oxidation to higher temperatures on Pt DOC and Pt OC, whereas CO pre-exposure inhibited acetate formation. CO oxidation occurred at lower temperatures during ethanol and CO co-oxidation on Pd+Pt DOC.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS2002

Influence of Cooling Channel Geometry on the Thermal Response in Silicon Nitride Plates Studied

Engine manufacturers are continually attempting to improve the performance and efficiency of internal combustion engines. Usually they raise the operating temperature or reduce the cooling air requirement for the hot section turbine components. However, the success of these attempts depends on finding materials that are lightweight, are strong, and can withstand high temperatures. Ceramics are among the top candidate materials considered for such harsh applications. They hold low-density, high-temperature strength, and thermal conductivity, and they are undergoing investigation as potential materials for replacing nickel-base alloys and superalloys that are currently used for engine hot-section components. Ceramic structures can withstand higher operating temperatures and a harsh combustion environment. In addition, their low densities relative to metals help reduce component mass. The long-term objectives of the High Temperature Propulsion Components (HOTPC) Project are to develop manufacturing technology, thermal and environmental barrier coatings (TBC/EBC), and the analytical modeling capability to predict thermomechanical stresses in minimally cooled silicon nitride turbine nozzle vanes under simulated engine conditions. Two- and three-dimensional finite element analyses with TBC were conducted at the NASA Glenn Research Center. Nondestructive evaluation was used to determine processing defects. The study included conducting preliminary parametric analytical runs of heat transfer and stress analyses under steady-state conditions to demonstrate the feasibility of using cooled Si3N4 parts for turbine applications. The influence of cooling-channel shapes (such as circular, square, and ascending-order cooling channels) on cooling efficiency and thermal stresses was investigated. Temperature distributions were generated for all cases considered under both cooling and no-cooling conditions, with air being the cooling medium. The table shows the magnitude of the maximum and minimum temperature obtained for the plates under air cooling. Each channel's cross-sectional shape delivered a different temperature; however, the two-dimensional analyses for circular and square or equal-side rectangular holes produced close results. Moreover, the model of the panel with ascending order cooling channels experienced the lowest temperature. A difference of near 260 C was found among the three cooling-hole configurations investigated. The ascending-order cooling channels arrangement showed superior performance by attaining the lowest temperature (1077 C) in comparison to the circular (1379 C) and square (1343 C) channels for the same cooling-hole size. This indicates that the panel with ascending-order cooling channels is the most suitable configuration regardless of the complexity involved in its manufacture. More details pertaining to this study are reported.

Abdul-Aziz, Ali↗
DOE OSTI2025

2D CFD of lean premixed hydrogen–air flame quenching under locomotive engine conditions

Hydrogen (H 2 ) is a promising fuel for reducing emissions in heavy-duty internal combustion engines (ICEs), but its low quenching distance increases the risk of flame propagation into narrow crevice regions, such as piston-liner gaps. This work uses detailed CFD simulations with finite-rate chemistry to investigate premixed H 2 –air flame quenching in a two-dimensional (2D) region consistent with the piston-liner gap of a diesel ICE. Model accuracy was assessed by comparison with experimentally measured quenching distances in an annular stepwise diverging tube (ASDT). A parametric study was conducted to assess the influence of crevice width (0.05–1.18 mm), pressure (50–150 bar), unburned gas temperature (431–573 K), and equivalence ratio ( Φ= 0.3–0.6). Results show that the critical Péclet number for flame survival is no greater than 3.25, consistent with prior literature, even under ultra-lean and high-pressure conditions (Φ ≤ 0.3, > 50 bar). Additionally, flames with Péclet numbers exceeding 6.15 exhibited front wrinkling, suggesting the onset of velocity-driven instabilities and enhanced flame robustness. These findings help define thresholds for flame quenching in confined geometries and support the safe design of H 2 fueled ICEs.

08 HYDROGEN↗
NASA NTRS1995

Low-order nonlinear dynamic model of IC engine-variable pitch propeller system for general aviation aircraft

This paper presents a dynamic model of an internal combustion engine coupled to a variable pitch propeller. The low-order, nonlinear time-dependent model is useful for simulating the propulsion system of general aviation single-engine light aircraft. This model is suitable for investigating engine diagnostics and monitoring and for control design and development. Furthermore, the model may be extended to provide a tool for the study of engine emissions, fuel economy, component effects, alternative fuels, alternative engine cycles, flight simulators, sensors, and actuators. Results show that the model provides a reasonable representation of the propulsion system dynamics from zero to 10 Hertz.

Richard, Jacques C.↗
NASA NTRS2001

Silicon Nitride Plates for Turbine Blade Application: FEA and NDE Assessment

Engine manufacturers are continually attempting to improve the performance and the overall efficiency of internal combustion engines. The thermal efficiency is typically improved by raising the operating temperature of essential engine components in the combustion area. This reduces the heat loss to a cooling system and allows a greater portion of the heat to be used for propulsion. Further improvements can be achieved by diverting part of the air from the compressor, which would have been used in the combustor for combustion purposes, into the turbine components. Such a process is called active cooling. Increasing the operating temperature, decreasing the cooling air, or both can improve the efficiency of the engine. Furthermore, lightweight, strong, tough hightemperature materials are required to complement efficiency improvement for nextgeneration gas turbine engines that can operate with minimum cooling. Because of their low-density, high-temperature strength, and thermal conductivity, ceramics are being investigated as potential materials for replacing ordinary metals that are currently used for engine hot section components. Ceramic structures can withstand higher operating temperatures and other harsh environmental factors. In addition, their low densities relative to metals helps condense component mass (ref. 1). The objectives of this program at the NASA Glenn Research Center are to develop manufacturing technology, a thermal barrier coating/environmental barrier coating (TBC/EBC), and an analytical modeling capability to predict thermomechanical stresses, and to do minimal burner rig tests of silicon nitride (Si3N4) and SiC/SiC turbine nozzle vanes under simulated engine conditions. Furthermore, and in support of the latter objectives, an optimization exercise using finite element analysis and nondestructive evaluation (NDE) was carried out to characterize and evaluate silicon nitride plates with cooling channels.

Abdul-Aziz, Ali↗