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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 55 records · Page 3

Combustion of Various Highly Reactive Fuels in a 3.84- by 10-inch Mach 2 Wind Tunnel

The following fuels and fuel combinations injected from the top wall of a Mach 2 wind tunnel were successfully burned and gave associated pressure rises: aluminum borohydride, pentaborane, mixtures containing up to 41 percent JP-4 fuel in aluminum borohydride, tandem injections of aluminum borohydride, tandem injections of JP-4 fuel and aluminum borohydride, trimethyl aluminum with water injections, and diethyl aluminum hydride with water injections. The following fuels could not be ignited at the tunnel conditions (static pressure, 5.6 in. Hg; static temperature, -148 F): trimethylborane, triethylborane, propylpentaborane, ethyl- decaborane, and vinylsilane. Studies in which the heated region was probed by water injections indicated that the flow downstream of the flame front is subsonic and recirculating.

Allen, Harrison, Jr.↗

Influence of Tire Tread Pattern and Runway Surface Condition on Braking Friction and Rolling Resistance of a Modern Aircraft Tire

A series of taxiing tests was conducted at the Langley landing­ loads track with both braked and unbraked (freely rolling) single and tandem wheels equipped with 32x8.8 type VII aircraft tires of dif­ferent tread designs to obtain data on tire and braking characteristics during operation on dry and on contaminated concrete and asphalt run­ ways. Contaminants used were water, slush, JP-4 jet fuel, and organic and detergent fire-extinguishing foams. Forward velocities for the tests ranged from approximately 13 to 104 knots. Vertical loads of approximately 9,000 to 22,000 pounds and tire inflation pressures of 85 to 350 pounds per square inch were used. Results indicated that the unbraked tire rolling resistance increased with increasing forward velocity on dry and on contaminated runway surfaces. Peak tire-ground friction coefficients developed during wheel braking decreased rapidly with increasing velocity on contaminated runways but remained relatively unchanged on dry runways as the forward velocity was increased. Dry-runway friction coeffi­cients were found to be relatively insensitive to tire tread pattern. However, the magnitude of the friction coefficients developed by tires on contaminated runways was extremely sensitive to the tire tread pat­ tern used, with circumferential-groove treads developing the highest values of friction coefficient, and smooth and dimple treads the lowest values for the tread patterns and runway conditions investigated.

Horne, Walter B.↗

Experimental Study of Ballistic-Missile Base Heating with Operating Rocket

A rocket of the 1000-pound-thrust class using liquid oxygen and JP-4 fuel as propellant was installed in the Lewis 8- by 6-foot tunnel to permit a controlled study of some of the factors affecting the heating of a rocket-missile base. Temperatures measured in the base region are presented from findings of three motor extension lengths relative to the base. Data are also presented for two combustion efficiency levels in the rocket motor. Temperature as high as 1200 F was measured in the base region because of the ignition of burnable rocket gases. combustibles that are dumped into the base by accessories seriously aggravate the base-burning temperature rise.

BALLISTIC MISSILE↗

A Method for Prevention of Screaming in Rocket Engines

Lateral and longitudinal combustion-pressure oscillations that occurred in screaming combustion of a 1000-pound-thrust rocket engine using white fuming nitric acid and JP-4 fuel as propellants were successfully prevented by means of longitudinal fins in the combustion chamber. Fin position was critical, and complete attenuation was achieved only when the fins were located in a zone approximately 8 to 16 inches from the injector. Fins located in other zones, that is, near the injector or far downstream from the injector, did not stop the oscillations. When oscillations occurred in finned chambers, the longitudinal mode seemed more dominant than the lateral mode; in chambers without fins, the lateral mode tended to be dominant. The lateral oscillation was distorted and its intensity diminished by the fins. Fins, however, did not affect the frequencies; the longitudinal frequency varied inversely with chamber length, and lateral frequencies varied only slightly from an average of 6000 cycles per second.

ROCKET ENGINE NOISE↗

Flight Operation of a Pump-Fed Liquid-Hydrogen Fuel System

A pump-fed liquid-hydrogen fuel system was developed and flight tested in a B57 bomber. The aircraft was flown to an altitude of 50,000 feet and a Mach number of 0.75 with JP-4 fuel in both engines. One engine was then switched to hydrogen operation for approximately 11 minutes. The liquid-hydrogen pump used for these flights was a five-cylinder positive-displacement type submerged in the bottom of the hydrogen tank. The hydrogen flow regulator was able to maintain a constant engine speed even though pump speed and discharge pressure oscillated.

David B. Fenn↗

Factors affecting altitude relight performance of a double-annular ram-induction combustor

A test program was conducted to evaluate the altitude relight capabilities of a short-length, double-annular, ram-induction combustor which was designed for Mach 3 cruise operation. The use of distorted inlet-air flow profiles was tried to evaluate their effect on the relight performance. No significant improvement in altitude relight performance was obtained with this approach. A study was also made to determine the effects of the reference Mach number, the fuel temperature, and the fuel volatility (ASTM-A1 against JP-4) on the altitude relight performance. Decreasing the reference Mach number, increasing the fuel temperature, and using more volatile fuel all decrease the combustor pressure necessary for relight.

Schultz, D. F.↗

Enriched aluminide coatings for dispersion strengthened nickel materials

Improved aluminide/barrier coating combinations for dispersion strengthened nickel materials were investigated. The barrier materials involved alloys with refractory metal content to limit interdiffusion between the coating and the substrate, thereby minimizing void formation. Improved aluminide coatings involved the dispersion of aluminum-rich compounds. Coatings were tested in argon at 1533 K (2300 F) for 100 hours and in cyclic oxidation at 1422 K (2100 F). Two coatings on TDNiCr completed 300 hours of oxidation testing, none on TDNi. Selected coating combinations were evaluated in Mach 1 burner rig testing using JP-4 fuel and air at 1422 K (2100 F) and 1477 K (2200 F) for 350 and 100 hours, respectively. Static oxidation in 1-hour cycles was conducted at 1533 K (2300 F) for 100 hours. For comparison purposes a physical vapor deposition (PVD) NiCrAlY coating was tested concurrently. Only the NiCrA1Y coating survived the 1477 K (2200 F)/100-hour burner rig test and 275 hours of the 350-hour 1422 K (2100 F) test. Elevated temperature exposure reduced room temperature tensile properties but had little effect on elevated temperature properties.

Levinstein, M. A.↗

An initial step: A demonstration project

To initiate the transition into a clean and diverse energy environment independent of fossil-based fuels, the rapid development of a subsonic, hydrogen-fueled aircraft is recommended. Tables are presented on characteristics of synthetic fuels, comparisions with JP-4 and gasoline, comparison of nitric oxide emissions from hydrocarbon and hydrogen fuels vs. final flame temperature, and sensitivity limits of LH2 detectors.

Source record↗

Some Effects of Exposure to Exhaust-gas Streams on Emittance and Thermoelectric Power of Bare-wire Platinum Rhodium - Platinum Thermocouples

Thermocouples were exposed to exhaust gases from the combustion of propane, 72-octane gasoline, and JP-4 fuel. Exposure increased the emissivity of the thermocouple wire, which increased its radiation error. Two methods are presented for determining the emittance of the wires. The emissivity of a clean platinum rhodium-platinum thermocouple was approximately 0.2 in the temperature range investigated, while the emittance of an exposed thermocouple coated with exhaust residue was about 0.5. The exposure caused negligible change in the thermoelectric power of the thermocouples.

Glawe, George E↗

Effect of Dissolved Oxygen on the Filterability of Jet Fuels for Temperatures Between 300 Degrees and 400 Degrees F

The effect of dissolved oxygen in the filter-clogging characteristics of three JP-4 and two JP-5 fuels was studied at 300 degrees to 400 degrees F in a bench- scale rig, employing filter paper as the filter medium. The residence time of the fuel at the high temperature was approximately 6 seconds. For these conditions, the clogging characteristics of the fuels increased with both increasing temperature and increasing concentration of dissolved oxygen. The amount of insoluble material formed at high temperatures necessary to produce clogging of filters was very small, of the order of 1 milligram per gallon of fuel.

Mckeown, Anderson B↗

Analysis of ram-jet engine performance including effects of component changes

Calculated design-point performance of ram-jet engines using JP-4 fuel is presented for a wide range of engine total-temperature ratios and combustion-chamber-inlet Mach numbers for flight numbers from 1.5 to 4.0. The results include engine thrust, drag, fuel consumption, and area ratios. Data are also presented to illustrate the sensitivity of the results to variations in the assumed component parameters. A brief comparison is included between fixed-and variable-geometry engines.

Weber, Richard J↗

Performance at Simulated High Altitudes of a Prevaporizing Annular Turbojet Combustor Having Low Pressure Loss

An annular prevaporizing turbojet combustor having pressure losses lower than those obtained in current turbojet combustors was developed, Pressure losses of 2 to 4 percent, satisfactory temperature profiles, and combustion efficiencies of 98, 88, and 81 percent were obtained at 56,000, 70,000, and 80,000 feet respectively, for a simulated 5.2- pressure-ratio engine at rated speed and 0.6 flight Mach number with JP-4 fuel. Use of JP-5 fuel resulted in a small penalty in efficiency due, at least in part, to insufficient prevaporizer capacity.

Norgren, Carl T↗

The Appearance of a Boric Oxide Exhaust Cloud from a Turbojet Engine Operating on Trimethylborate Fuel

An investigation was conducted on the size and density of the boric oxide exhaust cloud from a J47-25 turbojet engine operating on trimethylborate fuel at sea-level static condition. Movies and still photographs were taken from the ground and from a helicopter. Objects could not be perceived through the main body of the cloud at distances up to 800 feet from the engine. Data are included on the amount of fallout from the cloud and the concentration of boric oxide in the cloud. A radiation detection device was set up to determine whether the glowing oxide particles would be more susceptible than hydrocarbon exhaust gases to this type of tracking device. The device showed an increase in radiation by a factor of 3 for trimethylborate over that for JP-4.

Lord, Albert M↗

Extended Operation of Turbojet Engine with Pentaborane

A full-scale turbojet engine was operated with pentaborane fuel continuously for 22 minutes at conditions simulating flight at a Mach number of 0.8 at an altitude of 50,000 feet. This period of operation is approximately three times longer than previously reported operation times. Although the specific fuel consumption was reduced from 1.3 with JP-4 fuel to 0.98 with pentaborane, a 13.2-percent reduction in net thrust was also encountered. A portion of this thrust loss is potentially recoverable with proper design of the engine components. The boron oxide deposition and erosion processes within the engine approached an equilibrium condition after approximately 22 minutes of operation with pentaborane.

Useller, James W↗

Experimental Evaluation of Rocket Exhaust Diffusers for Altitude Simulation

An experimental investigation of exhaust diffusers has been conducted to evaluate various methods of minimizing the overall pressure ratio (from chamber to ambient pressure) required to establish and maintain full expansion of the nozzle flow (altitude simulation). Exhaust-diffuser configurations investigated were (1) cylindrical diffusers, (2) diffusers with contraction, and (3) diffusers including a right-angle turn. Cylindrical diffusers were evaluated with primary nozzles of various area ratios and types, as well as two clustered configurations; the other diffusers were evaluated with individual nozzles of constant area ratio and varied type. Air was the working fluid, except for two check points obtained with JP-4 fuel and liquid-oxygen rocket engines and cylindrical diffusers. The minimum length-diameter ratio of cylindrical diffusers was about 6 for minimum pressure-ratio requirements. With cylindrical diffusers of adequate length, the pressure-ratio requirements were primarily a function of the ratio of diffuser to nozzle-throat areas and were essentially independent of primary-nozzle type (including two clustered configurations) or area ratio. The two check points obtained with rocket engines indicated the pressure-ratio requirements at given ratios of diffuser to nozzle-throat areas were lowered, as compared with the requirements with air, as a result of the reduced ratio of specific heats. The minimum length-diameter ratio of the contraction throat of convergent-divergent diffusers was also about 6 for minimum pressure-ratio requirements. With adequate contraction-throat length, the pressure-ratio requirements of such diffusers were appreciably below those of comparable cylindrical diffusers when used with conical and cutoff-isentropic nozzles, but not when used with a bell nozzle. Minimum pressure-ratio requirements of a diffuser including a simple long-radius right-angle turn at maximum diffuser area, obtained with the center of radius of the turn a minimum of 2 diffuser diameters downstream of the nozzle exit, were not appreciably above those of a comparable optimum cylindrical diffuser. A diffuser including a long-radius right-angle turn at a contraction minimum area had somewhat lower pressure-ratio requirements than the aforementioned simple turn.

Sivo, Joseph N.↗

Base Flow Characteristics for Several Four-Clustered Rocket Configurations at Mach Numbers from 2.0 to 3.5

A generalized study of base flow phenomena has been conducted with four 500-pound-thrust JP-4 fuel-liquid-oxygen rocket motors installed in the base of a 12-inch-diameter cylindrical model. Data were obtained over a Mach number and nozzle pressure ratio range of 2.0 to 3.5 and 340 to 600, respectively. Base heat flux, gas temperature, and pressure were highest in the center of the cluster core and decreased in a radial direction. Although a maximum heat flux of 93 Btu per square foot per second was measured within the cluster core, peripheral heat fluxes were low, averaging about 5 Btu per square foot per second for all configurations. Generally base heat flux was found to be independent of Mach number over the range investigated. Base heat flux within the cluster core was decreased by increasing motor spacing, motor extension, a combination of increasing nozzle area ratio and decreasing exit angle and gimbaling the two side engines. Small amounts of nitrogen injected within the cluster core sharply reduced core heat flux.

Musial, Norman T.↗

Preliminary Study of a Piston Pump for Cryogenic Fluids

Preliminary data are presented covering the performance of a low-speed, five-cylinder piston pump designed for handling boiling hydrogen. This pump was designed for a flow of 55 gallons per minute at 240 rpm with a discharge pressure of 135 pounds per square inch. Tests were made using JP-4 fuel, liquid nitrogen, and liquid hydrogen. Pump delivery and endurance characteristics were satisfactory for the range of operation covered. In connection with the foregoing pump development, the cavitation characteristics of a preliminary visual model, glass-cylinder pump and of a simple reciprocating disk were studied. Subcooling of approximately 0.60 F was obtained from the cavitation produced by reciprocating a disk in boiling nitrogen and in boiling water. The subcooling obtained in a similar manner with liquid hydrogen was somewhat less.

Biermann, Arnold E.↗