SEARCH · Engineering Papers

Results for “propeller aerodynamics”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29

All sources NASA NTRS DOE OSTI

NASA NTRS1989

Lifting-surface theory for propfan vortices impinging on a downstream wing

Retrofitment of commercial aircraft with propfans could introduce undesirable aerodynamic sources of structure-borne noise that are absent for current turbojet powerplants. This paper theoretically examines the whipping action of the vortex wake from a generic propeller on the downstream rigid wing that supports it. The model addresses the high-frequency/compressible regime of most anticipated propfan implementations and produces an analytic solution for the distributed wing airload due to the periodic vortex impingement. The analysis also yields an expression for the local unsteady lift obtained from integration over an arbitrary internal patch of wing surface, for the purpose of applying a practical number of such forces at the nodes of a finite-element model for the corresponding structure (wing response results are not included in the present paper). Reported estimates of induced wing loads for a conventional-propeller example of demonstration appear to be in the reasonable range of expectation.

Martinez, R.↗

NASA NTRS1989

Low Earth Orbit Raider (LER) winged air launch vehicle concept

The need to launch small payloads into low earth orbit has increased dramatically during the past several years. The Low Earth orbit Raider (LER) is an answer to this need. The LER is an air-launched, winged vehicle designed to carry a 1500 pound payload into a 250 nautical mile orbit. The LER is launched from the back of a 747-100B at 35,000 feet and a Mach number of 0.8. Three staged solid propellant motors offer safe ground and flight handling, reliable operation, and decreased fabrication cost. The wing provides lift for 747 separation and during the first stage burn. Also, aerodynamic controls are provided to simplify first stage maneuvers. The air-launch concept offers many advantages to the consumer compared to conventional methods. Launching at 35,000 feet lowers atmospheric drag and other loads on the vehicle considerably. Since the 747 is a mobile launch pad, flexibility in orbit selection and launch time is unparalleled. Even polar orbits are accessible with a decreased payload. Most importantly, the LER launch service can come to the customer, satellites and experiments need not be transported to ground based launch facilities. The LER is designed to offer increased consumer freedom at a lower cost over existing launch systems. Simplistic design emphasizing reliability at low cost allows for the light payloads of the LER.

Feaux, Karl↗

NASA NTRS1925

Aerodynamic Characteristics of Airfoils at High Speeds

This report deals with an experimental investigation of the aerodynamical characteristics of airfoils at high speeds. Lift, drag, and center of pressure measurements were made on six airfoils of the type used by the air service in propeller design, at speeds ranging from 550 to 1,000 feet per second. The results show a definite limit to the speed at which airfoils may efficiently be used to produce lift, the lift coefficient decreasing and the drag coefficient increasing as the speed approaches the speed of sound. The change in lift coefficient is large for thick airfoil sections (camber ratio 0.14 to 0.20) and for high angles of attack. The change is not marked for thin sections (camber ratio 0.10) at low angles of attack, for the speed range employed. At high speeds the center of pressure moves back toward the trailing edge of the airfoil as the speed increases. The results indicate that the use of tip speeds approaching the speed of sound for propellers of customary design involves a serious loss in efficiency.

Briggs, L J↗

NASA NTRSDate not supplied

Small Satellite-sized Hypersonic Inflatable Aerodynamic Decelerators for Interplanetary Science Missions

To make the most of ridesharing opportunities, small satellite (SmallSat) mission designers endeavor to pack as much payload into a SmallSat-class form factor as possible. The mass and volume constraints of this smaller vehicle class present a challenge for interplanetary mission sets that require a means of achieving orbit insertion at their destination of interest. For a fully propulsive orbit insertion design, this may translate to the propellant mass being a significant fraction of the overall vehicle mass and prolonged insertion time. Aerocapture is a single quick maneuver that can significantly reduce the required propellant mass for orbit insertion. Because aerocapture uses a planet’s atmosphere to achieve the necessary change in velocity, a protective aeroshell is needed. The constraints imposed on secondary payloads render traditional rigid aeroshells mass and space prohibitive for the SmallSat class of vehicles; thus, warranting consideration of deployable designs that can be stowed compactly until needed for atmospheric entry. The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is a deployable aeroshell that leverages inflatable toroids to achieve the large drag area needed for aerodynamic deceleration. While the technology is currently being analyzed for Mars human-scale missions, it has the potential applicability for interplanetary SmallSat-scale missions as well. This paper highlights a study conducted during an internship at NASA Langley Research Center to investigate the feasibility of using a scaled-down HIAD design in SmallSat aerocapture missions. Several scaling methodologies are investigated including use of parametric models and direct computer-aided design (CAD) model scaling. Candidate HIAD configurations that conform to secondary payload adapter requirements are identified. The Program to Optimize Simulated Trajectories II (POST2) is utilized to conduct orbit insertion performance and trajectory sensitivity studies using the candidate configurations at Earth, Venus, and Mars. The results of the study indicate that multiple SmallSat-sized HIAD designs, targeting a range of SmallSat payload classes, are feasible for planetary aerocapture missions to Mars and Venus as well as Earth-based aerocapture missions.

Shelly C. Mann↗

NASA NTRS1941

The aerodynamics of a wind-tunnel fan

The vortex blade-element theory modified to apply to an axial fan working in a duct is reviewed. Thrust and power coefficients for a fan are identified with the corresponding coefficients for airplane propellers. The relation of pressure produced by the fan to the blade-element coefficients is developed. The distribution of axial velocity of fluid through a fan is assumed to be controlled by the fan itself. The radial distribution of tangential velocity imported by the fan to fluid moving through the fan is shown to be independent of the axial-velocity distribution. A nondimensional coefficient, designated the rotation constant, is introduced. This constant is based solely upon design information. The use of the rotation constant in simplifying the design of a fan for a specific operating condition is demonstrated. Based on the use of the rotation constant, a graphical method is outlined by which the performance of a given fan in a given wind tunnel may be predicted and by which the distributions of axial velocity of the fluid through the fan under various operating conditions may be established.

THEORIES-VORTEX↗

NASA NTRS1923

Some new aerodynamical relations

This report contains three new relations extending the modern theory of aeronautics. They deal with phenomena in a frictionless fluid. The first part contains a relation between the power absorbed by an aerofoil and the power absorbed by a propeller. In the second part the exactness of the ordinary formula for the induced drag of an aerofoil is examined and the error is determined. In the third part the author shows that for the calculation of the air forces on bodies of considerable volume the imaginary sources and sinks equivalent to the flow around the body can be used in the same way as vortices are used for the calculation of lift and induced drag of wings.

Munk, Max M↗

NASA NTRS1978

VEEP: A Vehicle Economy, Emissions, and Performance simulation program

The purpose of the VEEP simulation program was to: (1) predict vehicle fuel economy and relative emissions over any specified driving cycle; (2) calculate various measures of vehicle performance (acceleration, passing manuevers, gradeability, top speed), and (3) give information on the various categories of energy dissipation (rolling friction, aerodynamics, accessories, inertial effects, component inefficiences, etc.). The vehicle is described based on detailed subsystem information and numerical parameters characterizing the components of a wide variety of self-propelled vehicles. Conventionally arranged heat engine powered automobiles were emphasized, but with consideration in the design toward the requirement of other types of vehicles.

Klose, G. J.↗

NASA NTRS1986

Flow prediction for propfan engine installation effects on transport aircraft at transonic speeds

An Euler-based method for aerodynamic analysis of turboprop transport aircraft at transonic speeds has been developed. In this method, inviscid Euler equations are solved over surface-fitted grids constructed about aircraft configurations. Propeller effects are simulated by specifying sources of momentum and energy on an actuator disc located in place of the propeller. A stripwise boundary layer procedure is included to account for the viscous effects. A preliminary version of an approach to embed the exhaust plume within the global Euler solution has also been developed for more accurate treatment of the exhaust flow. The resulting system of programs is capable of handling wing-body-nacelle-propeller configurations. The propeller disks may be tractors or pushers and may represent single or counterrotation propellers. Results from analyses of three test cases of interest (a wing alone, a wing-body-nacelle model, and a wing-nacelle-endplate model) are presented. A user's manual for executing the system of computer programs with formats of various input files, sample job decks, and sample input files is provided in appendices.

Samant, S. S.↗

NASA NTRS1990

Aerobrakes For A Manned Mars Mission

Paper presents results of study of aerobraking in manned mission to Mars. Describes geometry and aerodynamic characteristics of aerobraked vehicle. Discusses computer program, WTRAJ, used to simulate trajectories near planets. Analyzes aerocapture processes for both Mars and Earth. Examines mass efficiency, or saving in propellant mass, afforded by aerobraking.

Menees, G. P.↗

NASA NTRS2016

Design and Performance of the NASA SCEPTOR Distributed Electric Propulsion Flight Demonstrator

Distributed Electric Propulsion (DEP) technology uses multiple propulsors driven by electric motors distributed about the airframe to yield beneficial aerodynamic-propulsion interaction. The NASA SCEPTOR flight demonstration project will retrofit an existing internal combustion engine-powered light aircraft with two types of DEP: small "high-lift" propellers distributed along the leading edge of the wing which accelerate the flow over the wing at low speeds, and larger cruise propellers co-located with each wingtip for primary propulsive power. The updated high-lift system enables a 2.5x reduction in wing area as compared to the original aircraft, reducing drag at cruise and shifting the velocity for maximum lift-to-drag ratio to a higher speed, while maintaining low-speed performance. The wingtip-mounted cruise propellers interact with the wingtip vortex, enabling a further efficiency increase that can reduce propulsive power by 10%. A tradespace exploration approach is developed that enables rapid identification of salient trades, and subsequent creation of SCEPTOR demonstrator geometries. These candidates were scrutinized by subject matter experts to identify design preferences that were not modeled during configuration exploration. This exploration and design approach is used to create an aircraft that consumes an estimated 4.8x less energy at the selected cruise point when compared to the original aircraft.

Borer, Nicholas K.↗

NASA NTRS2019

Propeller-Wing Integration on the Parallel Electric-Gas Architecture with Synergistic Utilization Scheme (PEGASUS) Aircraft

Electrically powered aircraft show promise for reducing emissions and energy consumption, but many of the opportunities surrounding electric propulsion have yet to be explored. One opportunity is the use of multiple propulsors or distributed propulsion for improved propulsion airframe integration. However, the size, power, location, and optimum number of propulsors has not been thoroughly vetted. This paper describes the use of FlightStream, a surface vorticity solver, to investigate the aerodynamic-propulsion integration of four propulsors across the leading edge of a wing, two inboard and two at the wingtips, as proposed in the NASA Parallel Electric-Gas Architecture with Synergistic Utilization Scheme (PEGASUS) concept. FlightStream was used to determine the minimum power required for cruise for the PEGASUS aircraft. The study found that tip propellers are effective at lowering both viscous and induced drag when compared to inboard propellers alone or inboard propellers combined with tip propellers. Despite this drag savings, the propulsive efficiency was reduced when a single propeller class was used, resulting in a higher system power consumption when compared with using multiple propeller classes. Reductions in propeller efficiency are related to increases in disc and blade loading of the propeller; thus, larger propellers or higher tip speeds are seen as possible means of to improve system performance.

Blaesser, Nathaniel J.↗

NASA NTRS1987

Evaluation of installed performance of a wing-tip-mounted pusher turboprop on a semispan wing

An exploratory investigation has been conducted at the Langley Research Center to determine the effect of a wing-tip-mounted pusher turboprop on the aerodynamic characteristics of a semispan wing. Tests were conducted on a semispan model with an upswept, untapered wing and an airdriven motor that powered an SR-2 high-speed propeller located on the tip of the wing as a pusher propeller. All tests were conducted at a Mach number of 0.70 over an angle-of-attack range from approximately -2 to 4 deg at a Reynolds number of 3.82 x 10 to the 6th based on the wing reference chord of 13 in. The data indicate that, as a result of locating the propeller behind the wing trailing edge at the wing tip in the crossflow of the wing-tip vortex, it is possible to improve propeller performance and simultaneously reduce the lift-induced drag.

Patterson, James C., Jr.↗

NASA NTRS1961

Free-Flight Aerodynamic-Heating Data to Mach Number 10.4 for a Modified Von Karman Nose Shape

Aerodynamic-heating data have been obtained on a modified fineness-ratio-5.0 Von Karman nose shape at free-stream Mach numbers up to 10.4 with a rocket-propelled model. Transient skin temperatures were measured at one station, 26.6 inches behind the tip of a nose 31.6 inches long. A maximum skin temperature of 1,663 deg R was measured soon after the maximum Mach number was obtained. During the periods for which experimental Stanton numbers were presented, flow parameters just outside the boundary layer at the temperature measuring station varied as follows: the local Mach number varied in the range between 0.8 and 9.0 and the local Reynolds number varied in the range between 0.8 x 10(exp 6) and 35.5 x 10(exp 6). The ratio of skin temperature to local static temperature varied between 1.0 and 3.6. The experimental Stanton numbers agreed well with Van Driest's turbulent theory while the local Reynolds number was high - that is, while the local Reynolds number varied in a range above 6.8 x 10(exp 6). For local Reynolds numbers less than 3.5 x 10(exp 6) the experimental Stanton numbers were of the magnitude predicted by Van Driest's laminar theory. Transition from turbulent to laminar flow at the temperature measuring station, as indicated by the change in the magnitude of the Stanton number, occurred as the local Reynolds number decreased from 6.8 x 10(exp 6) to 3.5 x 10(exp 6) at essentially a constant local Mach number of about 9.0.

Bland, William M., Jr.↗

NASA NTRSDate not supplied

Preliminary Aeroacoustic Measurements from the AART in the NFAC 40-by 80-Foot Wind Tunnel

The primary objective: determine the aerodynamics and acoustics related to an auxiliary propulsor mounted behind an isolated wing in the National Full Scale Aerodynamic Complex 40-by 80-Foot Wind Tunnel. The primary data points match test conditions for in-flow stereo PIV measurements completed in the Ames 7x10 in 2018. The propeller consists of a Sensenich L26H commercial off the shelf blade set and hub, with a 26 inch diameter; propeller performance is measured with an internal balance integrated in the test stand. The wing is a NACA 0015 with a 12 inch chord; 58.5 inches in height for full wing configuration; 40.5 inches in height for the half wing configuration.

Aeroacoustics↗

NASA NTRS1986

Method for the prediction of the installation aerodynamics of a propfan at subsonic speeds: User manual

This document is the user's guide for the method developed earlier for predicting the slipstream wing interaction at subsonic speeds. The analysis involves a subsonic panel code (HESS code) modified to handle the propeller onset flow. The propfan slipstream effects are superimposed on the normal flow boundary condition and are applied over the surface washed by the slipstream. The effects of the propeller slipstream are to increase the axial induced velocity, tangential velocity, and a total pressure rise in the wake of the propeller. Principles based on blade performance theory, momentum theory, and vortex theory were used to evaluate the slipstream effects. The code can be applied to any arbitrary three dimensional geometry, expressed in the form of HESS input format. The code can handle a propeller alone configuration or a propeller/nacelle/airframe configuration, operating up to high subcritical Mach numbers over a range of angles of attack. Inclusion of a viscous modelling is briefly outlined. Wind tunnel results/theory comparisons are included as examples for the application of the code to a generic supercritical wing/overwing Nacelle with a powered propfan. A sample input/output listing is provided.

Chandrasekaran, B.↗

NASA NTRS1996

Inlet and Propulsion Integration of Scram Propelled Vehicles

The material to be presented in these two lectures begins with cycle considerations of the turbojet engine combined with a ramjet engine to provide thrust over the range of Mach 0 to 5. We will then examine in some detail the aerodynamic behavior that occurs in the inlet operating near the peak speed. Following that, we shall view a numerical simulation through a baseline scramjet engine, starting at the entrance to the inlet, proceeding into the combustor and through the nozzle. In the next segment, we examine a combined rocket and ramjet propulsion system. Analysis and test results will be examined with a view toward evaluation of the concept as a practical device. Two other inlets will then be reviewed: a Mach 12 inlet and a Mach 18 configuration. Finally, we close our lectures with a discussion of the Detonation Wave engine, and inspect the physical and chemical behavior obtained from numerical simulation. A few final remarks will be made regarding the application of CFD for hypersonic propulsion components.

Povinelli, Louis A.↗

NASA NTRS1984

Some aerodynamic considerations for advanced aircraft configurations

Recent NASA wind-tunnel investigations of advanced unconventional configurations are surveyed, with an emphasis on those applicable to general-aviation aircraft. Photographs of typical models and graphs of aerodynamic parameters are provided. The designs discussed include aft installation of tractor or pusher-propellor engines; forward-swept wings; canards; combinations of canard, wing, and horizontal tail; and propeller-over-the-wing configurations. Consideration is given to canard-wing flow-field interactions, natural laminar flow, the choice of canard airfoil, directional stability and control, and propulsion-system location.

Williams, L. J.↗

NASA NTRS1984

A new aerodynamic integral equation based on an acoustic formula in the time domain

An aerodynamic integral equation for bodies moving at transonic and supersonic speeds is presented. Based on a time-dependent acoustic formula for calculating the noise emanating from the outer portion of a propeller blade travelling at high speed (the Ffowcs Williams-Hawking formulation), the loading terms and a conventional thickness source terms are retained. Two surface and three line integrals are employed to solve an equation for the loading noise. The near-field term is regularized using the collapsing sphere approach to obtain semiconvergence on the blade surface. A singular integral equation is thereby derived for the unknown surface pressure, and is amenable to numerical solutions using Galerkin or collocation methods. The technique is useful for studying the nonuniform inflow to the propeller.

Farassat, F.↗