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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Wind tunnel performance results of swirl recovery vanes as tested with an advanced high speed propeller

Tests of swirl recovery vanes designed for use in conjunction with advanced high speed propellers were carried out at the NASA Lewis Research Center. The eight bladed 62.23 cm vanes were tested with a 62.23 cm SR = 7A high speed propeller in the NASA Lewis 2.44 x 1.83 m Supersonic Wind Tunnel for a Mach number range of 0.60 to 0.80. At the design operating condition for cruise of Mach 0.80 at an advance ratio of 3.26, the vane contribution to the total efficiency approached 2 percent. At lower off-design Mach numbers, the vane efficiency is even higher, approaching 4.5 percent for the Mach 0.60 condition. Use of the swirl recovery vanes essentially shifts the peak of the high speed propeller efficiency to a higher operating speed. This allows a greater degree of freedom in the selection of rpm over a wider operating range. Another unique result of the swirl recovery vane configuration is their essentially constant torque split between the propeller and the swirl vanes over a wide range of operating conditions for the design vane angle.

Gazzaniga, John A.↗
NASA NTRS1992

A logistics and potential hazard study of propellant systems for a Saturn 5 derived heavy lift (three-stage core) launch vehicle

The Bush Administration has directed NASA to prepare for a return to the Moon and on to Mars - the Space Exploration Initiative. To meet this directive, powerful rocket boosters will be required in order to lift payloads that may reach the half-million pound range into low earth orbit. In this report an analysis is presented on logistics and potential hazards of the propellant systems envisioned for future Saturn 5 derived heavy lift launch vehicles. In discussing propellant logistics, particular attention has been given to possible problems associated with procurement, transportation, and storage of RP-1, HL2, and LOX, the heavy lift launch vehicle propellants. Current LOX producing facilities will need to be expanded and propellant storage and some support facilities will require relocation if current Launch Pads 39A and/or 39B are to be used for future heavy noise-abatement measures. Included in the report is a discussion of suggested additional studies, primarily economic and environmental, which should be undertaken in support of the goals of the Space Exploration Initiative.

Whitney, E. Dow↗
NASA NTRS1992

An asymptotic theory of supersonic propeller noise

A theory for predicting the noise field of supersonic propellers with realistic blade geometries is presented. The theory, which utilizes a large-blade-count approximation, provides an efficient formula for predicting the radiation of sound from all three sources of propeller noise. Comparisons with a full numerical integration indicate that the levels predicted by this formula are quite accurate. Calculations also show that, for high speed propellers, the noise radiated by the Lighthill quadrupole source is rather substantial when compared with the noise radiated by the blade thickness and loading sources. Results from a preliminary application of the theory indicate that the peak noise level generated by a supersonic propeller initially increases with increasing tip helical Mach number, but is eventually reaches a plateau and does not increase further. The predicted trend shows qualitative agreement with the experimental observations.

Envia, Edmane↗
NASA NTRS1991

The engineering of a nuclear thermal landing and ascent vehicle utilizing indigenous Martian propellant

The following paper reports on a design study of a novel space transportation concept known as a 'NIMF' (Nuclear rocket using Indigenous Martian Fuel). The NIMF is a ballistic vehicle which obtains its propellant out of the Martian air by compression and liquefaction of atmospheric CO2. This propellant is subsequently used to generate rocket thrust at a specific impulse of 264 s by being heated to high temperature (2800 K) gas in the NIMFs' nuclear thermal rocket engines. The vehicle is designed to provide surface to orbit and surface to surface transportation, as well as housing, for a crew of three astronauts. It is capable of refueling itself for a flight to its maximum orbit in less than 50 days. The ballistic NIMF has a mass of 44.7 tonnes and, with the assumed 2800 K propellant temperature, is capable of attaining highly energetic (250 km by 34,000 km elliptical) orbits. This allows it to rendezvous with interplanetary transfer vehicles which are only very loosely bound into orbit around Mars. If a propellant temperature of 2000 K is assumed, then low Mars orbit can be attained; while if 3100 K is assumed, then the ballistic NIMF is capable of injecting itself onto a minimum energy transfer orbit to Earth in a direct ascent from the Martian surface.

Zubrin, Robert M.↗
NASA NTRS1992

An asymptotic theory of supersonic propeller noise

A theory for predicting the noise field of a propeller with a realistic blade geometry is presented. The theory, which utilizes a large blade count approximation, provides an efficient formula for predicting the radiation of sound from all three sources of propeller noise. Comparisons with full numerical integration indicate that the noise levels predicted by this formula are quite accurate. Calculations based on this method also show that the radiation from the Lighthill quadrupole source is rather substantial when compared with thickness and loading noise for high speed propellers. A preliminary application of the theory to the problem of the sensitivity of the peak noise levels generated by a supersonic propeller to the variations in its tip helical Mach number has produced a trend that is in qualitative agreement with the experimental observations.

Envia, Edmane↗
NASA NTRS1992

Forward rotor vortex effects on counter rotating propeller noise

Three configurations of a model counter rotating propeller manipulate the blade tip flow by: placing the CRP at angle of attack, installing shrouds, and turning the upstream blades to provide forward sweep. Flow visualization and flow measurements with thermal anemometry show no evidence of a tip vortex; however, a leading edge vortex was detected on aft swept blades. The modifications served to alter the strength and/or path of the leading edge vortex. The vortical flow is eliminated by forward sweep on the upstream propeller blades. Far field acoustic data from each test indicate only small influences on the level and directivity of the BPFs. The interaction tone at the sum of the two BPF's was significantly altered in a consistent manner. As the vortex system varied, the interaction tone was affected: far field noise levels in the forward quandrant increased and the characteristic noise minimum near the plane of rotation became less pronounced and in some cases were eliminated. If the forward propeller leading edge vortex system does not impact the rear propeller in the standard manner, a net increase in the primary interaction tone occurs for the model tested. If the leading edge vortex is removed, the interaction tone increases.

Laur, Michele↗
NASA NTRS1993

Effect of a rotating propeller on the separation angle of attack

The present study represents an extension of an earlier wind tunnel experiment performed with the P&W 17-in. Advanced Ducted Propeller (ADP) Simulator operating at Mach 0.2. In order to study the effects of a rotating propeller on the inlet flow, data were obtained in the UTRC 10- by 15-Foot Large Subsonic Wind Tunnel with the same hardware and instrumentation, but with the propellar removed. These new tests were performed over a range of flow rates which duplicated flow rates in the powered simulator program. The flow through the inlet was provided by a remotely located vacuum source. A comparison of the results of this flow-through study with the previous data from the powered simulator indicated that in the conventional inlet the propeller produced an increase in the separation angle of attack between 4.0 deg at a specific flow of 22.4 lb/sec-sq ft to 2.7 deg at a higher specific flow of 33.8 lb/sec-sq ft. A similar effect on separation angle of attack was obtained by using stationary blockage rather than a propeller.

Boldman, D. R.↗
NASA NTRS1992

Generic Propellants Transfer Unit (GPTU)

The Generic Propellants Transfer Unit (GPTU) is being designed to support spacecraft liquid propellant operations at the Kennedy Space Center (KSC) and Eastern Test Range (ETR). The GPTU will have a 500 gallon capacity and be Department Of Transportation (DOT) approved for over-the-road transportation of hypergolic propellants. The use of these containers will allow the users to increase efficiency and reduce the following costs: design/construction, transportation (to/from the launch site), propellant transfer operations, and decontamination operations. The user also acquires the flexibility of transporting to an offsite location for processing or storage without obtaining special exemptions or permits. These containers will incorporate their own quantity gaging and temperature sensing systems, and be integrated onto a transport trailer which contains work platforms and a fluid transfer system.

Cook, Christopher A.↗
NASA NTRS1993

Mars rover sample return mission utilizing in situ production of the return propellants

This paper presents an unmanned Mars sample return mission that utilizes propellants manufactured in situ from the Martian atmosphere for the return trip. A key goal of the mission is to demonstrate the considerable benefits that can be realized through the use of indigenous resources and to test the viability of this approach as a precursor to manned missions to Mars. Two in situ propellant combinations, methane/oxygen and carbon monoxide/oxygen, are compared to imported terrestrial hydrogen/oxygen within a single mission architecture, using a single Earth launch vehicle. The mission is assumed to be launched from Earth in 2003. Upon reaching Mars, the landing vehicle aerobrakes, deploys a small satellite, and lands on the Martian surface. Once on the ground, the propellant production unit is activated, and the product gases are liquefied and stored in the empty tanks of the Earth Return Vehicle (ERV). Power for these activities is provided by a dynamic isotope power system. A semiautonomous rover, powered by the indigenous propellants, gathers between 25 and 30 kg of soil and rock samples which are loaded aboard the ERV for return to Earth. After a surface stay time of approximately 1.5 years, the ERV leaves Mars for the return voyage to Earth. When the vehicle reaches the vicinity of Earth, the sample return capsule detaches, and is captured and circularized in LEO via aerobraking maneuvers.

Bruckner, A. P.↗
NASA NTRS1992

Spectral analysis of unsteady surface pressure on a pusher propeller

A propeller of an advanced turboprop testbed aircraft in pusher configuration is instrumented with 22 miniature blade-mounted transducers (BMTs) at two radii. Upstream pylon wake interaction with the propeller is the source of a one-per-cycle excitation for the blades in flight. The time history of fluctuating pressure signals over 26 flight conditions is statistically analyzed in the frequency domain. The rms amplitude of fluctuating pressure signals measured by suction surface BMTs indicates a very strong presence of the fundamental frequency over most of the upper surface. The pylon wake pressure signature on the propeller trailing edge, i.e., x/c not less than 0.80, shows predominantly random turbulence; hence, the amplitude of the fundamental frequency wave is fairly small. The resurgence of a large amplitude fundamental harmonic with coherent pylon wake signature further downstream, say at 90 percent chord, is unexpected behavior. The appearance of a dominating second propeller shaft order in the spectra of the rms pressure in transonic flight conditions identifies the presence of a two-per-cycle excitation source in the azimuthal direction. This is due to the presence of a shock wave, as evidenced by the pressure-time history plots.

Farokhi, Saeed↗
NASA NTRS1925

Propeller scale effect and body interference

This note shows that the main part of the discrepancy between full flight propeller performance and the performance of models in a wind tunnel is due to a scale effect, and that a minor part is caused by body interference. Analyses are made of propeller performances on several standard airplanes, and the actual brake horsepower compared with the power as calculated from model test data. The calculated power is based on that absorbed by a wind tunnel propeller model which is geometrically similar to the full scale propeller and is operating under the same ratio of V/nD.

Weick, Fred E↗
NASA NTRS1924

Micarta Propellers III : General Description of the Design

The design of propellers made of Micarta is discussed. The advantages of the material are noted, especially as compared with wood. The design changes necessitated by the use of Micarta are discussed with reference to the hub boss, the narrowing of the blade tips, the thinning of the blades, the angles of the leading and trailing edges, and the adjustment of the pitch. Results of flight tests show that the Micarta propeller gave a top speed of 2 miles per hour more than the wooden propeller while turning about 120 r.p.m slower, with about the same rate of climb. At top speed, the Micarta propeller shows an improvement of about 7 percent in fuel economy, although the plane is flying 2 miles per hour faster.

Caldwell, F W↗
NASA NTRS1924

Micarta propellers IV : technical methods of design

A description is given of the methods used in design of Micarta propellers. The most direct method for working out the design of a Micarta propeller is to start with the diameter and blade angles of a wooden propeller suited for a particular installation and then to apply one of the plan forms suitable for Micarta propellers. This allows one to obtain the corresponding blade widths and to then use these angles and blade widths for an aerodynamic analysis.

Caldwell, F W↗
NASA NTRS1933

Experiments with a Counter-propeller

This note describes tests made at Stanford University on a four-blade fixed counter-propeller in combination with a two-blade rotating propeller. It is shown that the efficiency of the normal form, well-designed air propeller can be increased about two percent over the full working range by the addition of fixed counter-propeller blades.

Lesley, E P↗
NASA NTRS1934

Negative Thrust and Torque Characteristics of an Adjustable-Pitch Metal Propeller

This report presents the results of a series of negative thrust and torque measurements made with a 4 foot diameter model of a conventional aluminum-alloy propeller. The tests were made in the 20-foot propeller-research tunnel of the National Advisory Committee for Aeronautics. The results show that the negative thrust is considerably affected by the shape and size of the body behind the propeller, that the maximum negative thrust increases with decrease in blade-angle setting, and that the drag of a locked propeller may be greatly reduced by feathering it into the wind. Several examples of possible applications of the data are given.

Hartman, Edwin P↗
NASA NTRS1937

Air Propellers in Yaw

Report presents the results of tests conducted at Stanford University of a 3-foot model propeller at four pitch settings and at 0 degree, 10 degrees, 20 degrees, and 30 degrees yaw. In addition to the usual propeller coefficients, cross-wind and vertical forces and yawing, pitching, and rolling moments were determined about axes having their origin at the intersection of the blade axis and the axis of rotation. The tests showed that the maximum efficiency was reduced only slightly for angles of yaw up to 10 degrees but that at 30 degrees yaw the loss in efficiency was about 10 percent. In all cases the cross-wind force was found to be greater than the cross-wind component of the axial thrust. With a yawed propeller an appreciable thrust was found for v/nd for zero thrust at zero yaw. Yawing a propeller was found to induce a pitching moment that increased in magnitude with yaw.

Lesley, E P↗
NASA NTRS1941

Propeller Analysis from Experimental Data

The operation of the propeller is analyzed by the use of the distribution of forces along the radius, combined with theoretical equations. The data were obtained in the NACA 20-foot wind tunnel on a 4-foot-diameter, two-blade propeller, operating in front of four body shapes, ranging from a small shaft to support the propeller to conventional NACA cowling. A method of estimating the axial and the rotational energy in the wake as a fractional part of the propeller power is given. A knowledge of the total thrust and torque is necessary for the estimation.

Stickle, George W↗
NASA NTRS1949

Application of Theodorsen's theory to propeller design

A theoretical analysis is presented for obtaining, by use of Theodorsen's propeller theory, the load distribution along a propeller radius to give the optimum propeller efficiency for any design condition. The efficiencies realized by designing for the optimum load distribution are given in graphs, and the optimum efficiency for any design condition may be read directly from the graph without any laborious calculations. Examples are included to illustrate the method of obtaining the optimum load distributions for both single-rotating and dual-rotating propellers.

Crigler, John L↗