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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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NASA NTRSDate not supplied

Green Propulsion : A NASA GSFC Assessment

In the ever-changing paradigm of efficient and capable spacecraft design, scientific missions continue pushing spacecraft subsystems to deliver effective solutions to meet challenging new mission/spacecraft applications. From an in-space storable liquid chemical propulsion perspective, monopropellant hydrazine is a dependable propellant. Bi-propellant architectures offer even superior performance, but add the complexity of a hypergolic fuel (hydrazine/ mono-methyl hydrazine) and oxidizer (Nitrogen Tetroxide/ mixed oxides of nitrogen) dual tank combination. These propulsion system designs (mono-propellant and bi-propellant) have high heritage, high propellant throughput qualified engines, widely tested material compatibility, qualified fluid delivery commercial-off-the-shelf components, known handling practices, and repeatable performance in successfully delivering on mission requirements. NASA and the broader propulsion community have historically selected hypergolic propellants for most mission applications. The space propulsion community has learned to successfully handle these highly toxic and hazardous materials, navigate the regulated use and the associated safety protocols, personnel protective equipment, and unique training standards – all requisite for loading spacecraft propulsion systems with hypergolic propellants. The question now arises as to what is next for in-space chemical propulsion? Is there an alternative, or even replacement, to the reliable hypergolic fluids, or propellant alternatives that promise increased mission benefits? With the evolution and proven advancements in innovative in-space green propellant technologies capable of delivering benefits to scientific missions, concern over the reliability and infusibility of this higher performing and safer to handle class of propellants is waning. As NASA science missions move forward with the potential flight infusion of green propulsion, NASA and the broader propulsion community are working to address remaining gaps in hardware development, reliability, performance, unique operational considerations, and risk mitigations for high value scientific assets.

Henry W. Mulkey↗
NASA NTRS2014

Preparing for Dawn's Mission at Ceres: Challenges and Opportunities in the Exploration of a Dwarf Planet

After escaping from Vesta in 2012, Dawn is continuing its 2.5-year flight to dwarf planet Ceres. Investigating this second destination promises to provide a view of an intriguing world of ice and rock, likely displaying fascinating geology entirely unlike any body yet orbited by a spacecraft. Dawn spends the significant majority of the time thrusting with its ion propulsion system to deliver the 3.6 km/s required to rendezvous with Ceres. Meanwhile, the operations team has developed the sequences that will be used there. Following orbit capture in March 2015, Dawn will fly to a series of four circular polar science orbits. The orbits, ranging from about 13,500 km to 375 km in altitude, are designed to optimize the scientific observations. The overall strategy for exploring Ceres is based strongly on the extremely successful 16 months of Vesta operations, during which Dawn met or exceeded all of its objectives. Nevertheless, the loss of two of the spacecraft's four reaction wheels has necessitated some important changes. Based on a very productive hydrazine conservation campaign in the interplanetary cruise and the development of new hydrazine-efficient methods of operating at Ceres, there is good reason to expect that Dawn will be able to accomplish all of its objectives regardless of the health of the reaction wheels. This paper describes the progress in traveling to Ceres as well as the plans for exploring this giant, icy world.

Vesta↗
NASA NTRS1962

DEVELOPMENT OF A LIGHT-WEIGHT REGENERATIVELY COOLED THRUST CHAMBER WITH BRAZED RIBS AND BRAZED OUTER WIRE TRAP

Design and fabrication procedures are discussed of a brazed-ribtype thrust chamber fabricated from stainless steel or inconel for a Sooo-lb thrust 20: 1 expansion-area-ratio regeneratively cooled liquidpropellant rocket engine which is designated as the JPL 6K Engine and operates at a chamber pressure of 150 psia. Hydrazine is used as the fuel and regenerative coolant and nitrogen tetroxide as the oxidizer. The nozzle-throat diameter is 5.42 in. The thrust chamber consists of a sheet-metal gas-side liner with longitudinal ribs spotwelded and brazed to the outer surface. Wire is wrapped over the ribs circumferentially, spot-welded to the ribs, and brazed. The liner, ribs, and wire form the coolant-passage walls. There are three basic advantages to this type of thrust chamber: light weight, ease of fabrication, and comparatively low cost. The total dry weight of a thrust chamber of this type and size made of 347 stainless steel is 46.2 lb, and the wet weight is 56.3 Ib. A total of 87 static engine tests were made on 19 of 23 thrust chambers fabricated by this technique. Four of the chambers tested had an expansion-area ratio of 20:1, and 15, which were shorter but had the same throat diameter, had an expansion-area ratio of 3.5:l. Accumulated test time was 1926 sec, including 558 sec regenerative cooling with hydrazine and 1368 sec cooling with water. One 20:l thrust chamber was subjected to 16 separate engine tests, with an accumulated test time of 399 sec, and was still in very good operating condition after the tests were completed. With water flowing through the coolant passages at 10 lb/sec, the measured nominal pressure drop between coolant manifolds of a 20:l thrust chamber wrapped with flat wire was 17.2 psi.

Thrust Chamber↗
NASA NTRS1972

Investigation of critical burning of fuel droplets

Measurements were made on the burning of liquid hydrazine, MMH, and UDMH in a combustion gas environment. The experimental range of these tests involved gas temperatures of 1660-2530 K, oxygen concentrations of 0-42% by mass and droplet diameters (employing both droplets and porous spheres) of 0.11-1.91 cm. at atmospheric pressure. A simplified hybrid combustion theory was developed which was found to correlate the present results as well as the experimental measurements of other investigators. Measurements were also made of the monopropellant strand burning rates and liquid surface temperatures of a number of nitrate ester fuels and hydrazine at elevated pressures. The temperature measurements for the nitrate esters were found to be in good agreement with a theoretical model which allowed for gas solubility in the liquid phase at high pressures. Experimental results were also obtained on the burning rates and liquid surface temperatures of a number of paraffin and alcohol fuels burning in air pressures up to 72 atm. For these tests, the fuels were burned from porous spheres in a natural convection environment. Initial findings on a pressurized flat flame burner are also described as well as the design of an oscillatory combustion apparatus to test the response of burning liquid fuels.

Allison, C. B.↗
NASA NTRS1972

Design, testing, fabrication and launch support of a liquid chemical barium release payload (utilizing the liquid fluorine-barium salt/hydrazine system)

A payload was designed which included a cryogenic oxidizer tank, a fuel tank, and burner section. Release of 30 lb of chemicals was planned to occur in 2 seconds at the optimum oxidizer to fuel ratio. The chemicals consisted of 17 lb of liquid fluorine oxidizer and 13 lb of hydrazine-barium salt fuel mixture. The fuel mixture was 17% barium chloride, 16% barium nitrate, and 67% hydrazine, and contained 2.6 lb of available barium. Two significant problem areas were resolved during the program: explosive valve development and burner operation. The release payload was flight tested, from Wallops Island, Virginia. The release took place at an altitude of approximately 260 km. The release produced a luminous cloud which expanded very rapidly, disappearing to the human eye in about 20 seconds. Barium ion concentration slowly increased over a wide area of sky until measurements were discontinued at sunrise (about 30 minutes).

Stokes, C. S.↗
NASA NTRS1973

Earth storable bimodal engine, phase 1

An in-depth study of an Earth Storable Bimodal (ESB) Engine using earth storable propellants N2O/N2H4 and operating in either a monopropellant or bipropellant mode was conducted. Detailed studies were completed for both a hot-gas, regeneratively cooled thrust chamber and a ducted hot-gas, film cooled thrust chamber. Hydrazine decomposition products were used for cooling in either configuration. The various arrangements and configurations of hydrazine reactors, secondary injectors, chambers and gimbal methods were considered. The two basic materials selected for the major components were columbium alloys and L-605. The secondary injector types considered were previously demonstrated by JPL and consisted of a liquid-on-gas triplet, a liquid-on-gas doublet, and a liquid-on-gas coaxial injector. Various design tradeoffs were made with different reactor types located at: the secondary injector station, the thrust chamber throat, and the nozzle/extension interface. Associated thermal, structural, and mass analyses were completed.

Source record↗
NASA NTRS1973

Equilibrium concentrations of N2H4 and its decomposition products at elevated temperatures and pressures

Liquid hydrazine is considered as a convenient source of hydrogen rather than just as a rocket fuel. For such purposes, the hydrogen is usually obtained by passing the hydrazine through a heated catalytic bed. One convenient measure of the effectiveness of a catalytic decomposition device as a whole is to compare the quantity of hydrogen produced with the equilibrium concentration of the gaseous species N2H4, NH3, N3, and H2 which would exist at the temperature and pressure found in various parts of the device. Calculations of the concentrations were carried out and are reported here. Following presentation of the results in both tabular and graphical forms is a comparison between the computed equilibrium concentrations and available experimental data.

Smetana, F. O.↗
NASA NTRS1973

Space shuttle seal material and design development for earth storable propellant systems

The results of a program to investigate and characterize seal materials suitable for space shuttle storable propellant systems are given. Two new elastomeric materials were identified as being potentially superior to existing state-of-the art materials for specific sealing applications. These materials were AF-E-124D and AF-E-411. AF-E-124D is a cured perfluorinated polymer suitable for use with dinitrogen tetroxide oxidizer, and hydrazine base fuels. AF-E-411 is an ethylene propylene terpolymer material for hydrazine base fuel service. Data are presented relative to low and high temperature characteristics as well as propellant exposure effects. Types of data included are: mechanical properties, stress strain curves, friction and wear characteristics, compression set and permeability. Sealing tests with a flat poppet-seal valve were conducted for verification of sealing capability. A bibliography includes over 200 references relating to seal design or materials and presents a concise tabulation of the more useful seal design data sources.

Source record↗
NASA NTRS1973

Application of selection techniques to electric-propulsion options on an advanced synchronous satellite

This paper addresses the comparison of several candidate auxiliary-propulsion systems and system combinations for an advanced synchronous satellite. Economic selection techniques, evolved at the Jet Propulsion Laboratory, are used as a basis for system option comparisons. Electric auxiliary-propulsion types considered include pulsed plasma and ion bombardment, with hydrazine systems used as a state-of-the-art reference. Current as well as projected electric-propulsion system performance data are used, as well as projected hydrazine system costs resulting from NASA standardization program projections.

Holcomb, L. B.↗
NASA NTRS1975

Environmental crack-growth behavior of high strength pressure vessel alloys

Results of sustained-load environmental crack growth threshold tests performed on six spacecraft pressure vessel alloys are presented. The alloys were Inconel 718, 6Al-4V titanium, A-286 steel, AM-350 stainless steel, cryoformed AISI 301 stainless steel; and cryoformed AISI 304L steel. The test environments for the program were air, pressurized gases of hydrogen, oxygen, nitrogen, and carbon dioxide, and liquid environments of distilled water, sea water, nitrogen tetroxide, hydrazine, aerozine 50, monomethyl hydrazine, and hydrogen peroxide. Surface flaw type specimens were used with flaws located in both base metal and weld metal.

Forman, R. G.↗
NASA NTRS1974

Attitude Control Propulsion Components, Volume 1

Effort was made to include as much engineering information on each component as possible, consistent with usefulness and catalog size limitations. The contents of this catalog contain components which were qualified for use with spacecraft monopropellant hydrazine and inert gas attitude control systems. Thrust ranges up to 44.5 N (10.0 lbf) for hydrazine and inert gas sytems were considered. Additionally, some components qualified for uses other than spacecraft attitude control are included because they are suitable for use in attitude controls systems.

Source record↗
NASA NTRS1974

Attitude Control Propulsion Components, Volume 2

Attitude control propulsion components are described, including hydrazine thrusters, hydrazine thruster and cold gas jet valves, and pressure and temperature transducers. Component-ordered data are presented in tabular form; the manufacturer and specific space program are included.

Source record↗
NASA NTRS1975

Monopropellant engine investigation for space shuttle reaction control system. Volume 3: Improvement of metal foam for catalyst retention

The retention of granular catalyst in a metal foam matrix was demonstrated to greatly increase the life capability of hydrazine monopropellant reactors. Since nickel foam used in previous tests was found to become degraded after long-term exposure the cause of degradation was examined and metal foams of improved durability were developed. The most durable foam developed was a rhodium-coated nickel foam. An all-platinum foam was found to be incompatible in a hot ammonia (hydrazine) environment. It is recommended to scale up the manufacturing process for the improved foam to produce samples sufficiently large for space shuttle APU gas generator testing.

Source record↗
NASA NTRS1974

Study of monopropellants for electrothermal thrusters

A 333 mN electrothermal thruster designed to use MIL-grade hydrazine was demonstrated to be suitable for operation with low freezing point monopropellants containing hydrazine azide, monomethylhydrazine, unsymmetrical-dimethylhydrazine and ammonia. The steady-state specific impulse was greater than 200 sec for all propellants. The pulsed-mode specific impulse for an azide blend exceeded 175 sec for pulse widths greater than 50 msec; propellants containing carbonaceous species delivered 175 sec pulsed-mode specific impulses for pulse widths greater than 100 msec. Longer thrust chamber residence times were required for the carbonaceous propellants; the original thruster design was modified by increasing the characteristic chamber length and screen packing density. Specific recommendations were made for the work required to design and develop flight worthy thrusters, including methods to increase propellant dispersal at injection, thruster geometry changes to reduce holding power levels and methods to initiate the rapid decomposition of the carbonaceous propellants.

Kuenzly, J. D.↗
NASA NTRS1976

Oscillatory combustion of liquid monopropellant droplets

A theoretical investigation was conducted on the open-loop combustion response of monopropellant droplets and sprays to imposed pressure oscillations. The theoretical model was solved as a perturbation analysis through first order, yielding linear response results. Unsteady gas phase effects were considered in some cases, but the bulk of the calculations assumed a quasi-steady gas phase. Calculations were conducted using properties corresponding to hydrazine decomposition. Zero-order results agreed with earlier measurements of hydrazine droplet burning in combustion gases. The droplet response was greatest (exceeding unity in some cases) for large droplets with liquid phase temperature gradients; at frequencies near the characteristic frequency of the liquid phase thermal wave. The response of a spray is less than that of its largest droplet, however, a relatively small percentage of large droplets provides a substantial response (exceeding unity in some cases).

Chanin, S. P.↗
NASA NTRS1976

Oscillatory combustion of monopropellant droplets

A theoretical study of combustion response to imposed pressure oscillations was conducted for monopropellant droplets and sprays. A first-order perturbation analysis was used, yielding the linear response. Transient gas phase phenomena were considered in some cases, but the bulk of the calculations assume a quasi-steady gas phase. The calculations employed properties representative of hydrazine decomposition. Calculated steady combustion results and response predictions for large hydrazine droplets agreed favorably with earlier measurements. Droplet and spray response factors in excess of unity were found. High response was associated with high pressures (1000-10,000 kN/sq m), large droplets, large mean liquid temperature gradients, and frequencies near the characteristic frequency of the liquid phase thermal wave. Spray response factors are lower than the response factor of the largest injected drop, however, a small percentage of large drops can still provide substantial response for the combustion process.

Chanin, S. P.↗