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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

An efficient hybrid scheme for the analysis of counter rotating propellers

An efficient solution procedure has been developed for analyzing inviscid unsteady flow past counter rotating propellers. This scheme is first order accurate in time and second order in space, and has been extended to fourth order accuracy in the axial direction. The solution procedure has been applied to a 2-bladed SR-7 single rotation propeller and to a GE F7/A7 counter rotation propeller. The pressure coefficients and the global quantities, power and thrust, show good comparison with experimental measurements.

Srivastava, R.↗
NASA NTRS1991

Periodic blade loads of a high speed propeller at small angle of attack

A code has been developed to predict the periodic aerodynamic loads of an advanced turboprop propeller. The analytical formulation accounts for flow three-dimensionality and flow periodicity due to the propeller inclination. The flow past the blade sections is computed using a thin layer Navier-Stokes solver. An iterative procedure is used to account for the induced axial and rotational velocities. The viscous periodic results are obtained for an eight-bladed Hamilton Standard SR-7L advanced propeller at a cruise Mach number of 0.813 and 35,000 ft. altitude. The results are shown for flow field quantities and performance parameters during the blade passage in the plane of rotation illustrating the periodic nature of blade flow separation and shocks. The time averaged coefficients of thrust and power are computed and compared with available flight test data. The results obtained show excellent agreement at cruise conditions for small nacelle angles of attack.

Takallu, M. A.↗
NASA NTRS1991

Paramagnetic propellant orientation

Deep space or low earth orbital propellant tanks require a fluid orientation system prior to engine firing or transfer. Some propellants such as cryogenic hydrogen, oxygen, and air are paramagnetic and respond to electromagnetic fields. A simple magnetic scheme is described for propellant orientation and a video tape presentation is provided that demonstrates some effects of magnetic fields on liquid air and oxygen in a low gravity simulator using the Leidenfrost phenomenon. When these Leidenfrost drops intersect the field lines, their flight paths are altered, some directly into the poles, some to the edges, and others move out of the field.

Hendricks, R. C.↗
NASA NTRS1991

Alkali metal propellants for MPD thrusters

Experiments performed in the United States in the 1960s and early 1970s and in the Soviet Union with alkali metal-fuelled MPD thrusters indicate performance levels substantially better than those achieved with gaseous propellants. Cathode wear appears to be less in engines with alkali metal propellants also. A critical review of the available data indicates that the data are consistent and reliable. An analysis of testing and systems-level considerations shows that pumping requirements for testing are substantially decreased and reductions in tankage fraction can be expected. In addition, while care must be exercised in handling the alkali metals, it is not prohibitively difficult or hazardous. The greatest disadvantage seems to be the potential for spacecraft contamination, but there appear to be viable strategies for minimizing the impact of propellant deposition on spacecraft surfaces. Renewed examination of alkali metal-fuelled MPD thrusters for ambitious SEI missions is recommended.

Polk, J. E.↗
NASA NTRS1992

An unsteady Euler scheme for the analysis of ducted propellers

An efficient unsteady solution procedure has been developed for analyzing inviscid unsteady flow past ducted propeller configurations. This scheme is first order accurate in time and second order accurate in space. The solution procedure has been applied to a ducted propeller consisting of an 8-bladed SR7 propeller with a duct of NACA 0003 airfoil cross section around it, operating in a steady axisymmetric flowfield. The variation of elemental blade loading with radius, compares well with other published numerical results.

Srivastava, R.↗
NASA NTRS1992

Laboratory test methods for combustion stability properties of solid propellants

An overview is presented of experimental methods for determining the combustion-stability properties of solid propellants. The methods are generally based on either the temporal response to an initial disturbance or on external methods for generating the required oscillations. The size distribution of condensed-phase combustion products are characterized by means of the experimental approaches. The 'T-burner' approach is shown to assist in the derivation of pressure-coupled driving contributions and particle damping in solid-propellant rocket motors. Other techniques examined include the rotating-valve apparatus, the impedance tube, the modulated throat-acoustic damping burner, and the magnetic flowmeter. The paper shows that experimental methods do not exist for measuring the interactions between acoustic velocity oscillations and burning propellant.

Strand, L. D.↗
NASA NTRS1992

Pulsed thrust propellant reorientation - Concept and modeling

The use of pulsed thrust to optimize the propellant reorientation process is proposed. The ECLIPSE code is used to study the performance of pulsed reorientation in small-scale and full-scale propellant tanks. A dimensional analysis of the process is performed and the resulting dimensionless groups are used to present and correlate the computational predictions of reorientation performance. Based on the results obtained from this study, it is concluded that pulsed thrust reorientation seems to be a feasible technique for optimizing the propellant reorientation process across a wide range of spacecraft, for a variety of missions, for the entire duration of a mission, and with a minimum of hardware design and qualification.

Hochstein, John I.↗
NASA NTRS1992

Advanced cryogenic propellant tank development status

The design and development of cryogenic propellant tanks with reduced weight and production costs is described with reference to applications for the National Launch System. The development program focused on the use of an aluminum-lithium alloy to demonstrate the production capability, manufacturability, and strength inherent in the novel material. Other key parameters for the alloy include fracture toughness, stress-corrosion resistance, and conformance to NASA specifications for cryogenic propellant tanks. The commercially produced aluminum-lithium alloy product forms are shown to operate acceptably in the temperature range for cryogenic propellant tanks. The alloy under consideration and the tank design are important advances in the development of ultralightweight launch-vehicle structures.

Scholz, E. F.↗
NASA NTRS1992

Effect of inert propellant injection on Mars ascent vehicle performance

A Mars ascent vehicle is limited in performance by the amount of propellant which can be brought from earth. In some cases the vehicle performance can be improved by injecting inert gas into the engine, if the inert gas is available as an in situ resource. CO2, N2 and Ar are constituents of the Martian atmosphere which are available at every point on the Martian surface and could be produced by a very simple processing technique, consisting essentially of compressing the atmosphere. The effect of inert gas injection on rocket engine performance was analyzed with a numerical code calculating chemical equilibrium in the engine, for engines of varying combustion chamber pressure, expansion ratio, oxidizer/fuel ratio, and inert injection fraction. Results of this analysis were applied to several candidate missions to determine how the required mass of return propellant needed in LEO could be decreased using inert propellant injection.

Colvin, James E.↗
NASA NTRS1992

Composite propellant tank study for very low cost space transportation

A study of life-cycle cost is conducted to determine acceptable options for composite propellant tanks at low cost and weight and for use at moderate pressures. The review examines all cost issues relevant to the production, mass, applications, and reliability of the tanks for pressure-fed rockets. Specific attention is given to the manufacturing and life-cycle issues relevant to the use of composite materials in this application since composites are effective materials for liquid propellant tanks. Specific costs and parametric considerations are given for several tank candidates with 62,303-lb capacities. The mass sensitivity of the fourth stage for the concept vehicle is shown to be high, and the use of a 325-psi fourth-stage tank is shown to yield the minimum cost/lb for the stage. Wound S-glass/epoxy composites can be employed as cost-effective replacements for steel in the design of liquid-propellant tanks.

Moser, D. J.↗
NASA NTRS1992

Effect of inert propellant injection on Mars ascent vehicle performance

A Mars ascent vehicle is limited in performance by the propellant which can be brought from Earth. In some cases the vehicle performance can be improved by injecting inert gas into the engine, if the inert gas is available as an in-situ resource and does not have to be brought from Earth. Carbon dioxide, nitrogen, and argon are constituents of the Martian atmosphere which could be separated by compressing the atmosphere, without any chemical processing step. The effect of inert gas injection on rocket engine performance was analyzed with a numerical combustion code that calculated chemical equilibrium for engines of varying combustion chamber pressure, expansion ratio, oxidizer/fuel ratio, and inert injection fraction. Results of this analysis were applied to several candidate missions to determine how the required mass of return propellant needed in low Earth orbit could be decreased using inert propellant injection.

Colvin, James E.↗
NASA NTRS1992

Metallized propellants for the human exploration of Mars

An evaluation is conducted of the use of novel, metallized-propellant propulsion systems to reduce launch masses for manned Mars missions on the basis of density and I(sp) enhancements. The use of metallized propellants leads to a 3.3 percent LEO mass saving which represents 38,000 kg less than O2/H2 propulsion. Attention is given to the possibility of using space-storable propellants for the Mars excursion vehicle, as an alternative to the storing of cryogenic H2 on Mars, albeit at the cost of lower I(sp).

Palaszewski, Bryan↗
NASA NTRS1993

Response of laminated composite plates to low-speed impact by airgun-propelled and dropped-weight impactors

An analytical procedure has been developed to determine the transient response of simply supported, rectangular laminated composite plates subjected to impact loads from airgun-propelled or dropped-weight impactors. A first-order shear-deformation theory has been included in the analysis to represent properly any local short-wavelength transient bending response. The impact force has been modeled as a locally distributed load with a cosine-cosine distribution. A double Fourier series expansion and the Timoshenko small increment method have been used to determine the contact force, out-of-plane deflections, and inplane strains and stresses at any plate location due to an impact force at any plate location. The results of experimental and analytical studies are compared for quasi-isotropic laminates. The results indicate the importance of including transverse shear deformation effects in the analysis for predicting the response of laminated plates subjected to both airgun-propelled and dropped-weight impactors. The results also indicate that plate boundary conditions influence the axial strains more significantly than the contact force for a dropped-weight impactor. The results of parametric studies identify a scaling approach based on impactor momentum that suggests an explanation for the differences in the responses of plates impacted by airgun-propelled or dropped-weight impactors.

Prasad, Chunchu B.↗
NASA NTRS1921

Resume of the theory of naval and aerial propulsive propellers and of airplanes in the rectilinear flight

Though dissimilar, these two subjects have been united because they have some points in common. The computation of the movement of an airplane can only be correctly established if we are in a position to know exactly the thrust and resisting torque of the propeller for the various values of slip, which may vary greatly according to circumstance. The first part of the work concerns propellers and introduces as a fundamental variable, the true slip (delta) with respect to the effective pitch, which is the advance per revolution of the propeller corresponding to no thrust. The second part deals with characteristic curves of an airplane.

Rateau, A↗
NASA NTRS1921

Study of the resistance offered by propellers rotating on an airstream

This report presents a series of tests conducted to verify the formula for thrust P = q(exp 2) D(exp 2) V(exp 2), where P represents thrust, V the velocity of the airstream, D the diameter of the propeller, and q the lifting quality of a comparative propeller which is called the conjugate propeller.

Lame, M↗
NASA NTRS1924

Micarta Propellers II : Method of Construction

The methods used in manufacturing Micarta propellers differ considerably from those employed with wood propellers on account of the hardness of the materials. The propellers must be formed accurately to size in a mold and afterwards balanced without the customary trimming of the material from the tips. Described here are the pressing and molding processes, filing, boring, balancing, and curing.

Caldwell, F W↗
NASA NTRS1925

Simplified propeller design for low-powered airplanes

The object of this report is to furnish the designer and builder of small airplanes a simple system for designing the propeller and making the drawing. An empirical design method is used, based on tests of model propellers in a wind tunnel and full scale tests of propellers in flight.

Weick, Fred E↗
NASA NTRS1928

Special Propeller Protractor

A special protractor was designed and built with a view towards supplying a simple, inexpensive, practical, portable instrument for making measurements to detect propeller warpage under practically all conditions, without the use of auxiliary equipment, and without having to remove the propeller from the airplane. A detailed description is given of the protractor. Techniques for measuring are described. Directions are given on how to use the protractor to set detachable blade-type propellers on an airplane.

Heim, A M↗