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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Measurements of the flow around a lifting-wing/body junction

Detailed measurements of all three mean velocity components and five of the six Reynolds stresses have been made around a model of a lifting-wing/body junction. The body was the flat working section floor of a small blower wind tunnel. Measurements of the surface pressure distribution on the NACA 0012 wing showed that the lift coefficient at the body surface was reduced by only 16 percent from the freestream value. It is shown that the near constancy of the bound vorticity requires the formation of aixal vorticity within the body boundary layer. This vorticity was concentrated in the two legs of the necklace vortex formed near the leading edge of the wing. The magnitude of the vorticity was always greater in the leg that developed on the suction surface. By four chord lengths downstream of the trailing edge, the turbulence structure of the suction leg was qualitatively similar to that of a single vortex imbedded in a turbulent boundary layer.

Wood, D. H.↗
NASA NTRS1993

Pump Propels Liquid And Gas Separately

Design for pump that handles mixtures of liquid and gas efficiently. Containing only one rotor, pump is combination of centrifuge, pitot pump, and blower. Applications include turbomachinery in powerplants and superchargers in automobile engines. Efficiencies lower than those achieved in separate components. Nevertheless, design is practical and results in low consumption of power.

Harvey, Andrew↗
NASA NTRS1992

A novel membrane device for the removal of water vapor and water droplets from air

One of the key challenges facing NASA engineers is the development of systems for separating liquids and gases in microgravity environments. In this paper, a novel membrane-based phase separator is described. This device, known as a water recovery heat exchanger (WRHEX), overcomes the inherent deficiencies of current phase-separation technology. Specifically, the WRHEX cools and removes water vapor or water droplets from feed-air streams without the use of a vacuum or centrifugal force. As is shown in this paper, only a low-power air blower and a small stream of recirculated cool water is required for WRHEX operation. This paper presents the results of tests using this novel membrane device over a wide range of operating conditions. The data show that the WRHEX produces a dry air stream containing no entrained or liquid water - even when the feed air contains water droplets or mist. An analysis of the operation of the WRHEX is presented.

Ray, Rod↗
NASA NTRS1992

Tests characterizing bioprocessor hardware for analytical modeling

The tests outlined in this paper were used to characterize the hardware components of the Salad Machine, a small NASA-developed bioprocessor. The data from these tests are presented, and the methods by which this data can be integrated into system mathematical models are briefly discussed. The subsystems and physical processes discussed include the lighting system, the air loop (condensing heat exchanger and the blower), heat transfer to the surroundings, and leakage. Through this effort it was learned that in the development of a test protocol, care should be taken to order the tests such that environmental parameters, particularly humidity, require as few large adjustments as possible. Sensor calibration and installation take a substantial amount of time, which should be built into the test schedule. Two properties were particularly hard to quantify: the air flow rate and the energy from the lighting system entering into the growth volume. Flow rate can be measured using the appropriate device for the system configuration and airflow. Lighting system radiation level was measured using three methods. The results of these methods varied substantially, putting off conclusive quantification of this value.

Gustavino, S.↗
NASA NTRS1986

Houseplants, Indoor Air Pollutants, and Allergic Reactions

The technology of using houseplant leaves for reducing volatile organics inside closed facilities has been demonstrated with formaldehyde and benzene. Philodendrons are among the most effective plants tested to date. Philodendron domesticum had demonstrated the ability to remove formaldehyde from small experimental chambers at a rate of 4.31 micro-g/sq cm leaf surface area with initial starting concentrations of 22 ppm. At initial starting concentrations of 2.3 ppm a formaldehyde removal rate of 0.57 micro-g/sq cm was achieved during a 24 hour test. Aleo vera demonstrated a much higher formaldehyde efficiency removal rate than Philodendron domesticum at low formaldehyde concentrations. During a 24 hour exposure period 5 ppm of formaldehyde were reduced to 0.5 ppm demonstrating a removal efficiency rate of 3.27 micro-g/sq cm. Removal efficiency rates can be expected to decrease with concentration levels because fewer molecules of chemicals come in contact with the leaf surface area. Several centimeters of small washed gravel should be used to cover the surface of pot plants when large numbers of plants are kept in the home. The reason for this is to reduce the exposed area of damp potting soil which encourages the growth of molds (fungi). The leaves of Philodendron domesticum and golden pothos (Scindapsus aureus) have also demonstrated their ability to remove benzene and carbon monoxide from closed chambers. A combination of activated carbon and plant roots have demonstrated the greatest potential for removing large volumes of volatile organics along with smoke and possible radon from closed systems. Although fewer plants are required for this concept a mechanical blower motor must be used to pull or push the air through the carbon-root filter. NASA studies on motor sizes and bioregeneration rates should be completed by 1988.

Wolverton, B. C.↗
NASA NTRS1932

Comparative Performance of a Powerplus Vane-type Supercharger and an N.A.C.A. Roots-type Supercharger

This report presents the results of tests of a Power plus supercharger and a comparison of its performance with the performance previously obtained with an N.A.C.A. Roots-type supercharger. The Powerplus supercharger is a positive displacement blower of the vane type having mechanically operated vanes, the movement of which is controlled by slots and eccentrics. The supercharger was tested at a range of pressure differences from 0 to 15 inches of mercury and at speeds from 500 to 2,500 r.p.m. The pressure difference across the supercharger was obtained by throttling the intake of a depression tank which was interposed in the air duct between the supercharger and the Durley orifice box used for measuring the air. The results of these tests show that at low pressure differences and at all speeds the power required by the Powerplus supercharger to compress a definite quantity of air per second is considerably higher than that required by the Roots. At pressure differences from 10 to 14 inches of mercury and at speeds over 2,000 r.p.m. the power requirements of the two superchargers are practically the same. At a pressure difference of 15 inches of mercury or greater and at a speed of 2,500 r.p.m. or greater the performance of the Powerplus supercharger is slightly better than that of the Roots. Because the Powerplus supercharger cannot be operated at a speed greater than 3,000 r.p.m. as compared with 7,000 r.p.m. for the Roots, its capacity is approximately one-half that of the Roots for the same bulk. The Powerplus supercharger is more complicated and less reliable than the Roots supercharger.

Schey, Oscar W↗
NASA NTRS1937

Heat transfer from cylinders having closely spaced fins

The heat-transfer coefficients have been determined for five steel cylinders having fins 1.22 inches wide and the spacing between the fins ranging from 0.022 to 0.131 inch. The cylinders were tested with and without baffles in a wind tunnel; they were also tested enclosed in jackets with the cooling air supplied by a blower. A maximum heat transfer was reached at a fin space of about 0.45 inch for the cylinders tested with each of the three methods of cooling investigated. The rise in temperature of the air passing between the fins and the change in flow pattern were found to be important factors limiting the heat transfer that may be obtained by decreasing the fin space. The use of baffles for directing the air around the cylinders with closely spaced fins proved very effective in increasing the over-all heat-transfer coefficient, provided that the spacing was not appreciably less than that for maximum heat transfer.

Biermann, Arnold E↗
NASA NTRS1937

Effect of air-entry angle on performance of a 2-stroke-cycle compression-ignition engine

An investigation was made to determine the effect of variations in the horizontal and vertical air-entry angles on the performance characteristics of a single-cylinder 2-stroke-cycle compression-ignition test engine. Performance data were obtained over a wide range of engine speed, scavenging pressure, fuel quantity, and injection advance angle with the optimum guide vanes. Friction and blower-power curves are included for calculating the indicated and net performances. The optimum horizontal air-entry angle was found to be 60 degrees from the radial and the optimum vertical angle to be zero, under which conditions a maximum power output of 77 gross brake horsepower for a specific fuel consumption of 0.52 pound per brake horsepower-hour was obtained at 1,800 r.p.m. and 16-1/2 inches of Hg scavenging pressure. The corresponding specific output was 0.65 gross brake horsepower per cubic inch of piston displacement. Tests revealed that the optimum scavenging pressure increased linearly with engine speed. The brake mean effective pressure increased uniformly with air quantity per cycle for any given vane angle and was independent of engine speed and scavenging pressure.

Earle, Sherod L↗
NASA NTRS1946

Flight Investigation of the Cooling Characteristics of a Two-row Radial Engine Installation III : Engine Temperature Distribution

The temperature distribution of a two-row radial engine in a twin-engine airplane has been investigated in a series of flight tests. The test engine was operated over a wide range of conditions at density altitudes of 5000 and 20,000 feet; quantitative results are presented showing the effects of flight and engine variables upon average engine temperature and over-all temperature spread. Discussions of the effect of the variables on the shape of the temperature patterns and on the temperature distribution of individual cylinders are also included. The results indicate that, for the tests conducted, the temperature distribution patterns were chiefly determined by the fuel-air ratio and cooling-air distributions. It was possible to calculate individual cylinder temperature, on the assumption of equal power distribution among cylinders, to within an average of plus or minus 14 degrees F. of the actual temperature. A considerable change occurred in either the spread or the thrust axis, the average engine fuel-air ratio, the engine speed, the power, or the blower ratio. Smaller effects on the temperature pattern were noticed with a change in cowl-flap opening and altitude. In most of the tests, a change in conditions affected the temperature of the barrels less than that of the heads. The variation of flight and engine variables had a negligible effect on the temperature distributions of the individual cylinders. (author)

Rennak, Robert M↗
NASA NTRS1951

Some effects of blade trailing-edge thickness on performance of a single-stage axial-flow compressor

A set of modified NACA 65-series blower blades designed for axial inlet velocity, high inlet Mach number, and high blade loading was investigated for trailing-edge thickness of 0.015, 0.030, and 0.045 inch to determine the effect of trailing-edge thickness on single-stage axial-flow-compressor performance. Trailing-edge thickness effects were small except at the highest tip speed investigated (915 ft/sec). Trailing-edge thickness up to 30 percent of maximum blade thickness were used without sacrifice of performance of NACA 65-series blades.

AIRFOILS - THICKNESS↗
NASA NTRS1929

Mathematical and experimental investigation of heat control and power increase in air-cooled aircraft engines

In order to understand the numerical relations between the air velocity, temperature of the cylinder walls, heat dissipation, cylinder dimensions and type of construction an experimental plant was installed in the Siemens and Halske laboratory. The experimental cylinder was exposed to the air stream of a wind tunnel. The compression chamber was heated by an electrically heated oil bath kept constantly in motion by a stirrer. The wall temperatures were measured by thermocouples. The air stream was produced a seven-watt blower. The air flowed through a current rectifier (honeycomb), diffuser, air chamber with quieting sieves and a nozzle.

ENGINES - AIR COOLED - POWER INCREASES↗
NASA NTRS1926

Description and Laboratory Tests of a Roots Type Aircraft Engine Supercharger

This report describes a roots type aircraft engine supercharger and presents the results of some tests made with it at the Langley Field Laboratories of the National Advisory Committee for Aeronautics. The supercharger used in these tests was constructed largely of aluminum, weighed 88 pounds and was arranged to be operated from the rear of a standard aircraft engine at a speed of 1 1/2 engine crankshaft speed. The rotors of the supercharger were cycloidal in form and were 11 inches long and 9 1/2 inches in diameter. The displacement of the supercharger was 0.51 cubic feet of air per revolution of the rotors. The supercharger was tested in the laboratory, independently and in combination with a Liberty-12 aircraft engine, under simulated altitude pressure conditions in order to obtain information on its operation and performance. From these tests it seems evident that the Roots blower compares favorably with other compressor types used as aircraft engine superchargers and that it has several features that make it particularly attractive for such use.

Ware, Marsden↗
NASA NTRS1927

Power Output and Air Requirements of a Two-stroke Cycle Engine for Aeronautical Use

This investigation was undertaken to determine the pressure and amount of air necessary for satisfactory high-speed, two-stroke cycle operation and thus permit the power requirements of the air pump or blower to be determined. Based on power output and air requirement here obtained the two-stroke cycle engine would seem to be favorable for aeronautical use. No attempts were made to secure satisfactory operation at idling speeds.

Paton, C R↗
NASA NTRS1929

An investigation of the use of discharge valves and an intake control for improving the performance of N.A.C.A. Roots type supercharger

This report presents the results of an analytical investigation on the practicability of using mechanically operated discharge valves in conjunction with a manually operated intake control for improving the performance of N. A. C. A. Roots type superchargers. These valves, which may be either of the oscillating or rotating type, are placed in the discharge opening of the supercharger and are so shaped and synchronized with the supercharger impellers that they do not open until the air has been compressed to the delivery pressure. The intake control limits the quantity of air compressed to engine requirements by permitting the excess air to escape from the compression chamber before compression begins. The percentage power saving and the actual horsepower saved were computed for altitudes from 0 to 20,000 feet. These computations are based on the pressure-volume cards for the conventional and the modified roots type superchargers and on the results of laboratory tests of the conventional type. The use of discharge valves shows a power saving of approximately 26 per cent at a critical altitude of 20,000 feet. In addition, these valves reduce the amplitude of the discharge pulsations and increase the volumetric efficiency. With slow-speed roots blowers operating at high-pressure differences even better results would be expected. For aircraft engine superchargers operating at high speeds these discharge valves increase the performance as above, but have the disadvantages of increasing the weight and of adding a high-speed mechanism to a simple machine. (author)

Schey, Oscar W↗
NASA NTRS1932

Wind-Tunnel Tests on Airfoil Boundary Layer Control Using a Backward-Opening Slot

This report presents the results of an investigation to determine the effect of boundary layer control on the lift and drag of an airfoil. Boundary layer control was accomplished by means of a backward-opening slot in the upper surface of the hollow airfoil. Air was caused to flow through this slot by a pressure which was maintained inside the airfoil by a blower. Various slot locations, slot openings, and wing pressures were used. The tests were conducted in the 5-foot atmospheric wind tunnel of the Langley Memorial Aeronautical Laboratory. Under the test conditions, the maximum lift coefficient was increased about 96 per cent for one slot arrangement, and the minimum drag coefficient was decreased about 27 per cent for another, both being compared with the results obtained with the unslotted airfoil. It is believed from this investigation that the above effects may be increased by the use of larger slot openings, better slot locations, multiple slots, improved airfoil profiles, and trailing edge flaps.

Bamber, Millard J↗
NASA NTRS1937

Cooling of Airplane Engines at Low Air Speeds

Report presents the results of a comprehensive experimental study carried out at full scale in the NACA 20-foot wind tunnel, the general purpose of which is to furnish information in regard to the functioning of the power plant and propeller unit under different conditions. This report deals particularly with the problem of the cooling of an airplane engines on the ground. The influence of different nose forms, skirts, flaps, propellers, spinners, and special blowers has been investigated.

Theodorsen, Theodore↗
NASA NTRS1939

Correction of Temperatures of Air-Cooled Engine Cylinders for Variation in Engine and Cooling Conditions

Factors are obtained from semiempirical equations for correcting engine-cylinder temperatures for variation in important engine and cooling conditions. The variation of engine temperatures with atmospheric temperature is treated in detail, and correction factors are obtained for various flight and test conditions, such as climb at constant indicated air speed, level flight, ground running, take-off, constant speed of cooling air, and constant mass flow of cooling air. Seven conventional air-cooled engine cylinders enclosed in jackets and cooled by a blower were tested to determine the effect of cooling-air temperature and carburetor-air temperature on cylinder temperatures. The cooling air temperature was varied from approximately 80 degrees F. to 230 degrees F. and the carburetor-air temperature from approximately 40 degrees F. to 160 degrees F. Tests were made over a large range of engine speeds, brake mean effective pressures, and pressure drops across the cylinder. The correction factors obtained experimentally are compared with those obtained from the semiempirical equations and a fair agreement is noted.

Schey, Oscar W↗
NASA NTRS1939

Surface heat-transfer coefficients of finned cylinders

An investigation to determine and correlate the experimental surface heat-transfer coefficients of finned cylinders with different air-stream cooling arrangements was conducted at the Langley Memorial Aeronautical Laboratory from 1932 to 1938. The investigation covered the determination of the effect of fin width, fin space, fin thickness, and cylinder diameter on the heat transfer. Wind-tunnel tests were made in the free air stream with and without baffles and also with various devices for creating a turbulent air stream. Tests were also made with blower.

Ellerbrock, Herman H , Jr↗