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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Al6061-RAM2 Development and Hot-Fire Testing using Additive Manufacturing Laser Powder Directed Energy Deposition for Liquid Rocket Engine Channel-Cooled Nozzles

Aluminum 6061-RAM2 is a high-strength aluminum feedstock developed for additive manufacturing (AM)processes. This alloy leverages Reactive Additive Manufacturing (RAM) technology. The RAM aluminum alloys were developed to be weldable—therefore printable—while equaling or exceeding strength properties of high strength wrought aluminum alloys. NASA and industry partners developed Laser Powder Directed Energy Deposition (LP-DED)additive manufacturing of Al6061-RAM2 for use in aerospace applications. Efforts included establishing build parameters, characterizing the alloy, fabricating components, and completing hot-fire testing of complex internal channel-cooled nozzles. These efforts are to address the growing need for large-scale parts using high-performance light-weight materials. Two rocket engine nozzles were fabricated using LP-DED Al6061-RAM2 that included integral cooling channels. The Al6061-RAM2 has completed process development and initial properties were established. This paper provides an overview of the LP-DED process development, material characterization and properties, component manufacturing, supplemental development, and hot-fire testing. Results from hot-fire testing are provided for a lander-class 31kN (7,000lbf) thrust engine using Liquid Oxygen (LOX)/Liquid Hydrogen (LH2) and LOX/Methane (LCH4).

Al6061-RAM2↗
NASA NTRS2019

Additive Manufacturing of NASA HR-1 Material for Liquid Rocket Engine Component Applications

NASA HR-1 is a high-strength Fe-Ni superalloy designed to resist high pressure, hydrogen environment embrittlement, oxidation, and corrosion. NASA HR-1 was originally developed at NASA in the 1990’s and derived from JBK-75 to increase strength and ductility in high-pressure hydrogen environments. The NASA HR-1 chemistry was formulated to meet requirements for liquid rocket engine applications, specifically components used in a high-pressure hydrogen environment. Recent developments using additive manufacturing (AM) have made this material an attractive option for channel-cooled nozzles under the Rapid Analysis and Manufacturing Propulsion Technology (RAMPT) program and other liquid rocket engine component applications. The RAMPT program has baselined to fully evolve and characterize NASA HR-1 material. NASA HR-1 meets materials requirements for liquid rocket engine components, including good hydrogen resistance, high conductivity, good low cycle fatigue performance, and high elongation and strength for channel-cooled nozzles in high heat flux environments. Initial development and characterization has been completed using blown powder Directed Energy Deposition (DED) and Laser Powder Bed Fusion (L-PBF) additive manufacturing techniques to develop material test samples and nozzle hardware. NASA HR-1 powder has been sourced and characterized from several powder suppliers, and a series of development and hardware samples completed fabrication using DED and L-PBF. Characterization of the material has included heat treatment development, metallography, chemistry evaluations, mechanical testing, measurement of thermophysical properties, and fabrication of relevant nozzle hardware to demonstrate feasibility. This paper presents results from the process and early materials development and provide future development work including hardware fabrication.

Katsarelis, Colton↗
NASA NTRS1998

Research on liquid lubricants for space mechanisms

Four research areas at the NASA Lewis Research Center involving the tribology of space mechanisms are highlighted. These areas include: soluble boundary lubrication additives for perfluoropolyether liquid lubricants, a Pennzane dewetting phenomenon, the effect of ODC-free bearing cleaning processes on bearing lifetimes, and the development of a new class of liquid lubricants based on silahydrocarbons.

Jones, William R., Jr.↗
NASA NTRS1999

Research on Liquid Lubricants for Space Mechanisms

Four research areas at the NASA Glenn Research Center involving the tribology of space mechanisms are highlighted. These areas include: soluble boundary lubrication additives for perfluoropolyether liquid lubricants, a Pennzane dewetting phenomenon, the effect of ODC-free bearing cleaning processes on bearing lifetimes and the development of a new class of liquid lubricants based on silahydrocarbons.

Jones, William R., Jr.↗
NASA NTRSDate not supplied

Liquid Droplet Printing

The center has recently invested in a new additive manufacturing technology known as liquid metal jetting or liquid droplet printing. The Additec ElemX machine’s process utilizes wire feedstock fed into a ceramic crucible, where it is melted and ejected by pulsed Lorentz force using an external coil. The team will start with material characterization of various commercially available aluminum alloys to establish process parameters, repeatability, mechanical properties, and microstructure. Future research will consider additional alloys and explore concepts that may potentially adapt the technology for relevance in zero or low gravity environments. The printer has a 12”x12”x4.7” build volume and 0.24mm minimum layer height, with surface finishes comparable to sand castings.

liquid droplet printing↗
DOE OSTI2022

Modular Adaptive Packing for Integrally Cooled Absorbers

Process intensification is one cornerstone in ION Clean Energy’s (ION) efforts to lowering CO2 capture cost. ION has modeled, designed, and fabricated an innovative gas-liquid contactor known as Modular Adaptive Packing (MAP). During two successful SBIR Phase I and II projects entitled: “Rapid Design and Testing of Novel Gas-Liquid Contacting Devices for Post-Combustion CO2 Capture via 3D-printing”, ION developed and proved this new technology at bench scale. MAP, a 3D-printed lattice-structured packing, combines the absorber gas/liquid contactor with an innovative in-situ heat-exchanger. Thanks to the capabilities of 3D-printing, the lattice structure of MAP contains hollow channels through which coolant water can be pumped to remove the heat of reaction from CO2 absorption. ION refers to this novel method of heat exchange as intracooling. After 25.4 cm (10 in) diameter MAP modules were fabricated, ION built and tested a packing characterization rig at its pilot facility in Boulder, Colorado, U.S.A. To provide baseline results for the characterization rig, ION tested Sulzer’s Mellapak™ 250Y (MP250Y) as a standard structured packing. ION’s MAP was then compared directly to the baseline MP250Y packing to evaluate key indicators including pressure drop, liquid hold-up, and effective area. MAP has a higher pressure drop than MP250Y at the same gas velocities in addition to greater liquid holdup. However, ION found that MAP displays a higher wetting coverage of 93% compared to 65% for MP250Y and reduces shearing forces that result in undesirable droplet formation. Using Optimized Gas Treating’s (OGT) rate-based simulation software ProTreat®, a conceptual evaluation of MAP was modeled for a CO2 absorber using 30 wt% MEA solvent over a range of lean loadings at 90% CO2 capture from a coal-fired power plant. ION modeled a 25-meter column absorber for both the standard MP250Y packing and a hybrid column. The hybrid absorber contained 10 m of MP250Y packing at the top and bottom with the middle 5 meters comprised of MAP. Compared to a traditional intercooled absorber, MAP can remove 22% more heat and increase overall MEA carrying capacity by 4% without increasing overall pressure drop.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS2012

Stability Analysis of Intertank Formed Skin/Stringer Compression Panel with Simulated Damage

The External Tank (ET) is a component of the Space Shuttle launch vehicle that contains fuel and oxidizer. During launch, the ET supplies the space shuttle main engines with liquid hydrogen and liquid oxygen. In addition to supplying fuel and oxidizer, it is the backbone structural component of the Space Shuttle. It is comprised of a liquid hydrogen (LH2) tank and a liquid oxygen (LOX) tank, which are separated by an Intertank. The Intertank is a stringer-stiffened cylindrical structure with hat-section stringers that are roll formed from aluminum-lithium alloy Al-2090. Cracks in the Intertank stringers of the STS-133 ET were noticed after a November 5, 2010 launch attempt. The cracks were approximately nine inches long and occurred on the forward end of the Intertank (near the LOX tank), along the fastener line, and were believed to have occurred while loading the ET with the cryogenic propellants. These cracks generated questions about the structural integrity of the Intertank. In order to determine the structural capability of the Intertank with varying degrees of damage, a finite element model (FEM) simulating a 1995 compression panel test was analyzed and correlated to test data. Varying degrees of damage were simulated in the FEM, and non-linear stability analyses were performed. The high degree of similarity between the compression panel and the Intertank provided confidence that the ET Intertank would have similar capabilities.

Harper, David W.↗
NASA NTRS2019

Additive Manufacturing Development and Hot-Fire Testing of Liquid Rocket Channel Wall Nozzles Using Blown Powder Directed Energy Deposition Inconel 625 and JBK-75 Alloys

Additive manufacturing (AM) is being investigated at NASA and across much of the rocket propulsion industry as an alternate fabrication technique to create complex geometries for liquid engine components that offers schedule and cost saving opportunities. The geometries that can be created using AM offer a significant advantage over traditional techniques. Internal complexities, such as internal coolant channels for combustion chambers and nozzles that would typically require several operations to manufacture traditionally can be fabricated in one process. Additionally, the coolant channels are closed out as a part of the AM build process, eliminating the complexities of a traditional process like brazing or plating. The primary additive manufacturing technique that has been evaluated is powder bed fusion (PBF), or selective laser melting (SLM), but there is a scale limitation for this technique. There are several alternate additive manufacturing techniques that are being investigated for large-scale nozzles and chambers including directed energy deposition (DED) processes. A significant advantage of the DED processes is the ability to adapt to a robotic or gantry CNC system with a localized purge or purge chamber, allowing unlimited build volume. This paper will discuss the development and hot-fire testing of channel-cooled nozzles fabricated utilizing one form of DED called blown powder deposition. This initial development work using blown powder DED is being explored to form the entire channel wall nozzle with integral coolant channels within a single AM build. Much of this development is focused on the design and DED-fabrication of complex and thin-walled features and on characterization of the materials properties produced with this techniques in order to evolve this process. Subscale nozzles were fabricated using this DED technique and hot-fire tested in Liquid Oxygen/Hydrogen (LOX/GH2) and LOX/Kerosene (LOX/RP-1) environments accumulating significant development time and cycles. The initial materials that were evaluated during this testing were high-strength nickel-based Inconel 625 and JBK-75. Further process development is being completed to increase the scale of this technology for large-scale nozzles. This paper will summarize the general design considerations for DED, specific channel-cooled nozzle design, manufacturing process development, property development, initial hot-fire testing and future developments to mature this technology for regeneratively-cooled nozzles. An overview of future development at NASA will also be discussed.

Gradl, Paul R.↗
NASA NTRS2013

High-Performance, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants

The synthesis and characterization of six new ionic liquids, with fluoroether moeties on the imidazolium ring, each with vapor pressures shown to be <10(exp -7 Torr at 25 C, have been demonstrated. Thermal stability of the ionic liquids up to 250 C was demonstrated. The ionic liquids had no measurable influence upon viscosity upon addition to perfluoropolyether (PFPE) base fluids. They also had no measureable influence upon corrosion on steel substrates upon addition to base fluids. In general, 13 to 34% lower COFs (coefficients of friction), and 30 to 80% higher OK load of base fluids upon addition of the ionic liquids was shown. The compound consists of a 1,3-disubstituted imidazolium cation. The substituents comprise perfluoroether groups. A bis(trifluoromethanesulfonyl) imide anion counterbalances the charge. The fluorinated groups are intended to enhance dispersion of the ionic liquid in the PFPE base fluid. The presence of weak Van der Waals forces associated with fluorine atoms will limit interaction of the substituents on adjacent ions. The longer interionic distances will reduce the heat of melting and viscosity, and will increase dispersion capabilities.

Bergeron, Bryan↗
NASA NTRS1993

Foil bearing performance in liquid nitrogen and liquid oxygen

Space transfer vehicles and other power and propulsion systems require long-life turbopumps. Rolling-element bearings used in current turbopumps do not have sufficient life for these applications. Process fluid foil bearings have established long life, with exceptional reliability, over a wide range of temperatures and fluids in many high-speed turbomachinery applications. However, actual data on bearing performance in cryogenic fluids has been minimal. The National Aeronautics and Space Administration (NASA) and AlliedSignal Aerospace Systems and Equipment (ASE) have attempted to characterize the leaf-type compliant foil bearing in oxygen and nitrogen. The work performed under a joint internal research and development program between Marshall Space Flight Center (MSFC) and ASE demonstrated that the foil bearing has load capacities of at least 266 psi in liquid oxygen and 352 psi in liquid nitrogen. In addition, the bearing demonstrated a direct damping coefficient of 40 to 50 lb-sec/in. with a damping ratio of .7 to 1.4 in. liquid nitrogen using a bearing sized for upper-stage turbopumps. With the results from this testing and the years of successful use in air cycle machines and other applications, leaf-type compliant foil bearings are ready for testing in liquid oxygen turbopumps.

Genge, Gary G.↗
DOE OSTI2022

Initial Design and Experimental Results of a Novel Near-Isothermal Compressor for Heat Pump Applications

In efforts to increase the efficiency of residential and commercial air conditioners and heat pumps, it is found that the compressor has the highest electrical energy usage of the system. Therefore, it is appropriate to try to increase the efficiency of this component to reduce its energy usage. Another challenge with heat pump design is that some compressor types have drawbacks that make modulation difficult. To answer these challenges, we are developing an isothermal liquid compressor. The compressor uses propylene glycol to compress carbon dioxide. In the compression chamber the propylene glycol can enter either from the bottom to create a liquid piston for compression or it can enter through a spray nozzle at the top of the chamber. In the latter case, heat transfer from the gas to be compressed to the liquid droplets is high. This allows near isothermal operation of the compressor, which increases the efficiency by 17% to 30%, compared to adiabatic compression. In addition, the isothermal liquid compressor enables very efficient and simple part load modulation.Experimental results demonstrating the operation of the liquid compressor are presented. Initial data demonstrated a temperature rise of 7 K at pressure ratios of almost 4. For comparison at the same initial pressure, temperature, and pressure ratio, adiabatic compression would result in a temperature increase of approximately 70 K. Plotting data on a P-h diagram demonstrates that the compression started at superheated state and ended in supercritical state. Testing was later performed with repeated compressions in the superheated region of the P-h diagram at liquid flow rates of 2 x 10-3 m3/min and 2 x 10-3 m3/min to understand the limitations of the prototype for use with an actual heat pump system. This work demonstrated a novel cycle on a T-s diagram. Results from this work will be used to develop a second-generation prototype where more rapid cycling is possible.

Kowalski, Steve↗
DOE OSTI2025

Minimal implicit-solvent coarse-grained simulation of Pluronic block copolymers with ionic liquids

Pluronic block copolymers, composed of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) in a triblock structure (PEO–PPO–PEO), are well known for their amphiphilic character and ability to self‐assemble into micelles in aqueous solution. The addition of ionic liquids (ILs) can further modulate the core–shell structures of these copolymers, influencing their stability, critical micellization temperature, and size. However, fully atomistic simulations often become prohibitively expensive due to the size and complexity of these systems. In this work, coarse‐grained simulations using a minimal implicit‐solvent model were performed to examine how two classes of ILs, namely, 1‐alkyl‐3‐methylimidazolium ([C n C 1 im]) and 1‐alkyl‐3‐methylpyrrolidinium ([C n C 1 pyrr]), change the micellization of Pluronic block copolymers in aqueous solution. The effects of IL concentration and alkyl group length were investigated, and the model greatly improved the efficiency of simulating large‐scale micelle systems. Furthermore, the numerical simulations are qualitatively compared with experimental investigations. Our results show that adding ILs expands the micelle core by embedding IL tails among the PPO blocks, thereby increasing overall micelle size. Less polar ILs generally induce more pronounced micellar growth. However, the effect of IL tail length on conformation and micellar packing is non‐monotonic. Up to moderate chain lengths (around C8–C10), the IL tails can extend sufficiently to increase local separation within the micelle; at longer tail lengths, enhanced hydrophobic clustering and steric hindrance cause the tails to bend or fold, capping further expansion. In addition, although block copolymer chains tend to pack more closely in the presence of longer‐tailed ILs, the random coil size of an individual polymer chain does not necessarily shrink. Meanwhile, these insights provide a deeper understanding of how Pluronic/IL systems interact, informing applications in drug delivery, cosmetics, food, and environmental engineering. Finally, our minimal implicit‐solvent model can be applied to larger systems and longer timescales, substantially reducing computational cost while reproducing key structural trends observed experimentally.

Atomistic simulations↗
DOE OSTI2021

The Corrected Distortion model for Lagrangian spray simulation of transcritical fuel injection

In this work, we present a detailed implementation and validation of the droplet modeling framework proposed by Dahms and Oefelein (2016) into the engine commercial CFD software CONVERGE using the User Defined Function (UDF) interface. The model accounts for the nonlinear deformation and oscillation experienced by liquid spray droplet injected into high pressure and temperature. Lagrangian spray simulations of Engine Combustion Network (ECN) Spray A are performed. Model validation against standard experimental measurements of liquid velocity, vapor mixture fraction is conducted. To perform more rigorous model validation, new experimental measurements based on Diffused Back Illumination (DBI) are introduced. The new measurements are processed for Projected Liquid Volume (PLV), which offers as close as possible one-to-one model validation for liquid penetration while offering new insights into the spray physics. Comparison with a One-D model based on adiabatic mixing theory by Siebers (1999) and Desantes et al. (2007) are also conducted. Through these model validation exercises, it is shown that the new framework improves liquid-phase penetration predictions, following a tendency for enhanced evaporation, compared to the standard approach for both Reynolds Average Navier Stokes (RANS) and Large Eddy Simulation (LES). Additionally, at the liquid length, maximum mixture fraction values predicted by the new approach are in good agreement those of an adiabatic mixing model. Qualitative analysis of the spray behaviors during the early stage of the injection process reveals that the proposed framework predicts significant increase in droplet evaporation rate with lower drop drag compared to the current standard approach.

42 ENGINEERING↗
DOE OSTI2025

Current and candidate additives for environmentally acceptable lubricants—A review

The world consumes approximately 40 million tons of lubricants annually, and nearly half of them end up in the environment because of leaks, discharges, and evaporation, causing significant environmental and economic impacts. The need for moving toward environmentally acceptable lubricants (EALs) is increasingly being recognized. Synthetic ester, polyalkylene glycol, vegetable oil, and water are among the base fluids approved by the U.S. Environmental Protection Agency for EALs. However, neat base fluids cannot fully meet the lubrication requirements without incorporating functional additives such as anti-wear, antioxidant, corrosion inhibitor, and viscosity modifiers. Both the performance and environmental compatibility of lubricant additives are critical. In this article, current and candidate EAL additives, both in liquid and solid forms, are reviewed, with a focus on their functionalities in friction and wear reduction, toxicity, and biodegradability. Finally, a perspective for future research on EAL additives is discussed.

42 ENGINEERING↗
DOE OSTI2022

Ionic Liquid Engineering in Perovskite Photovoltaics

Over the past decade, perovskite photovoltaics have approached other currently available technologies and proven to be the most prospective type of solar cells. Although the many-sided research in this very active field has generated consistent results with regard to their undisputed consistently increasing power conversion efficiency, it also produced several rather contradictory opinions. Among other important details, debate surrounding their proneness to surface degradation and poor mechanical robustness, as well as the environmental footprint of this materials class, remains a moot point. The application of ionic liquids appears as one of the potential remedies to some of these challenges due to their high conductivity, the opportunities for chemical “tuning” of the structure, and relatively lower environmental footprint. This article provides an overview, classification, and applications of ionic liquids in perovskite solar cells. Here, we summarize the use and role of ionic liquids as versatile additives, solvents, and modifiers in perovskite precursor solution, in charge transport layer, and in interfacial and stability engineering. Finally, challenges and the future prospects for the design and/or selection of ionic liquids with a specific profile that meets the requirements for next-generation highly efficient and stable perovskite solar cells are proposed.

14 SOLAR ENERGY↗
NASA NTRS1975

Analysis of liquid metal embrittlement from a bond energy viewpoint

Absorption induced embrittlement of solid metals by certain liquid metals is analyzed through an Engel-Brewer calculation of the solid-liquid interaction energy, and of the effect of the latter in reducing fracture surface energy. The reduction in fracture surface energy is estimated by comparison of the electronic contribution to the solid-liquid interaction energy with solid-solid bond energy for some 40 liquid-solid couples. Regular solution theory is used to estimate mutual solubility as the relative difference in parameter values. Embrittlement can be predicted by using reduction in fracture surface energy and solubility parameter difference as critical variables. The effect of solute additions to the liquid on the degree of embrittlement is interpreted via the same two variables; the principal effect of solutes is to modify solubility relationships at the solid-liquid interface.

Kelley, M. J.↗
NASA NTRS1959

Effect of Ozone Addition on Combustion Efficiency of Hydrogen: Liquid-Oxygen Propellant in Small Rockets

An experimental study shows that 2 percent by weight ozone in oxygen has little effect on overall reactivity for a range of oxidant-fuel weight ratios from 1 to 6. This conclusion is based on characteristic-velocity measurements in 200-pound-thrust chambers at a pressure of 300 pounds per square inch absolute with low-efficiency injectors. The presence of 9 percent ozone in oxygen also did not affect performance in an efficient chamber. Explosions were encountered when equipment or procedure permitted ozone to concentrate locally. These experiments indicate that even small amounts of ozone in oxygen can cause operational problems.

Miller, Riley O.↗