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Results for “PROPELLER THRUST & TORQUE”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Experimental and Theoretical Study of Propeller Spinner/Shank Interference

A fundamental experimental and theoretical investigation into the aerodynamic interference associated with propeller spinner and shank regions was conducted. The research program involved a theoretical assessment of solutions previously proposed, followed by a systematic experimental study to supplement the existing data base. As a result, a refined computational procedure was established for prediction of interference effects in terms of interference drag and resolved into propeller thrust and torque components. These quantities were examined with attention to engineering parameters such as two spinner finess ratios, three blade shank forms, and two/three/four/six/eight blades. Consideration of the physics of the phenomena aided in the logical deduction of two individual interference quantities (cascade effects and spinner/shank juncture interference). These interference effects were semi-empirically modeled using existing theories and placed into a compatible form with an existing propeller performance scheme which provided the basis for examples of application.

Cornell, C. C.↗
NASA NTRS1940

Propeller rotation noise due to torque and thrust

Sound pressure of the first four harmonics of rotation from a full-scale two-blade propeller were measured and are compared with values calculated from theory. The comparison is made (1) for the space distribution with constant tip speed and (2) for fixed space angles with variable tip speed. A relation for rotation noise from an element of radius developed by Gutin is given showing the effect of number of blades on the rotation noise.

Deming, Arthur F↗
NASA NTRS1977

Optimum acoustic design of free-running low speed propellers

A theoretical analysis is conducted concerning the effect of blade loading on the noise output of a free-running propeller in axial motion. The minimization of the mean square sound pressure at a point in space is considered, taking into account constraints on propeller thrust and torque. Attention is given to aerodynamic equations, acoustic equations, the expansion of the aerodynamic variables, and the nonlinear programming formulation.

Ormsbee, A. I.↗
NASA NTRS1923

Determination of climbing ability

The vertical distribution of the pressure, temperature, and density of the atmosphere varies from day to day. Thus, rates of climb on different days cannot be compared directly, but must be corrected with reference to a standard rate of diminution of air density with increasing altitude. The following problem, therefore, has to be solved. An airplane has climbed on a certain day under prevailing atmospheric conditions as shown by the barograph. How would the same airplane climb in a standard atmosphere? This problem has already been dealt with by Everling, using the monthly and yearly mean of the vertical temperature distribution. Von Mises solved the problem by arithmetical methods. Here, conditions are examined which shorten or lengthen the climbing time. In establishing the corrected barogram, computation seems more practical than graphical treatment. The basis of the answer to the question answered here is summed up in the remark that lift, drag, propeller thrust, and torque and engine power depend only on the density of the air and do not change with the pressure and temperature, provided that the density remains constant.

Blasius, H↗
NASA NTRS1929

Force measurements on airplanes

The most essential phenomena of aircraft should be classified according to their origin and then measured. Information can thus be obtained in a quicker, cheaper, and more reliable way than otherwise would be possible.

HUB DYNAMOMETERS, ETC↗
NASA NTRSDate not supplied

System Identification for Propellers at High Incidence Angles

Propellers used for electric vertical takeoff and landing (eVTOL) aircraft propulsion systems experience a wide range of aerodynamic conditions, including large incidence angles relative to oncoming airflow. In oblique flow, propellers exhibit deviations in thrust and torque oriented along the propeller axis of rotation, as well as significant off-axis forces and moments. Although important for modeling eVTOL aircraft aerodynamics, sparse experimental data or mathematical models exist for propellers at incidence. This paper describes a propulsion system modeling methodology for the Langley Aerodrome No. 8 (LA-8) tandem tilt-wing, eVTOL aircraft. System identification methods are applied to isolated propeller wind tunnel data gathered across the vehicle's flight envelope to develop a mathematical model of the propulsion system, including a static motor model, dynamic motor model, and propeller aerodynamic model. Modeling results validated against data withheld from the modeling process indicate good predictive capability and agree with theoretical expectations. The results are followed by a discussion of model implementation strategies into high-fidelity eVTOL aircraft simulations.

system identification↗
NASA NTRS2021

System Identification for Propellers at High Incidence Angles

Propellers used for electric vertical takeoff and landing (eVTOL) aircraft propulsion systems experience a wide range of aerodynamic conditions, including large incidence angles relative to oncoming airflow. In oblique flow, propellers exhibit deviations in thrust and torque oriented along the propeller axis of rotation, as well as significant off-axis forces and moments. Although important for modeling eVTOL aircraft aerodynamics, sparse experimental data or mathematical models exist for propellers at incidence. This paper describes a propulsion system modeling methodology for the LA-8 tandem tilt-wing, eVTOL aircraft. System identification methods are applied to isolated propeller wind tunnel data gathered across the vehicle's flight envelope to develop a mathematical model of the propulsion system, including a static motor model, dynamic motor model, and propeller aerodynamic model. Modeling results validated against data withheld from the modeling process indicate good predictive capability and agree with theoretical expectations. The results are followed by a discussion of model implementation strategies into high-fidelity eVTOL aircraft simulations.

system identification↗
NASA NTRS1977

Propeller Study. Part 1: Introduction and Overview

A general aerodynamic-acoustic theory was developed for determining the acoustical design of propellers used on general aviation aircraft. Data from the theoretical investigation were applied in the design of a propeller whose thrust and torque were measured during a series of YO-3A aircraft flight tests.

Ormsbee, A. I.↗
NASA NTRS1954

A theoretical study of the effect of forward speed on the free-space sound-pressure field around propellers

The sound-pressure field of a rotating propeller in forward flight in free space is analyzed by replacing the normal-pressure distribution over the propeller associated with thrust and torque by a distribution of acoustic pressure doublets acting at the propeller disk and subject to uniform rectilinear motion. The basic element used to synthesize the field is the pressure field of a concentrated force moving uniformly at subsonic speeds, for which an expression generalizing one of Lamb's for the fixed concentrated force is given. The sound field is expressed by integration over the propeller disk, and also by integration over an effective ring, and is given both for the near pressure field and, in a simpler form, for the far field. Some illustrated examples are calculated and discussed.

Garrick, I E↗
NASA NTRS1980

Experimental verification of propeller noise prediction

Results of experimental measurements of the sound fields of 1/4-scale general aviation propellers are presented and experimental wake surveys and pressure signatures obtained are compared with theoretical predictions. Experiments were performed primarily on a 1C160 propeller model mounted in front of a symmetric body in an anechoic wind tunnel, and measured the thrust and torque produced by propeller at different rotation speeds and tunnel velocities, wakes at three axial distances, and sound pressure at various azimuths and tip speeds with advance ratio or tunnel velocity constant. Aerodynamic calculations of blade loading were performed using airfoil section characteristics and a modified strip analysis procedure. The propeller was then modeled as an array of point sound sources with each point characterized by the force and volume of the corresponding propeller section in order to obtain the acoustic characteristics. Measurements are found to agree with predictions over a wide range of operating conditions, tip speeds and propeller nacelle combinations, without the use of adjustable constants.

Succi, G. P.↗
NASA NTRS1979

The analysis of propellers including interaction effects

Analytical and experimental studies were undertaken on propellers operating in the unsteady flow field produced by interaction effects due to the fuselage, wing, and nacelles. Methods were developed and verified experimentally for determining the velocity field in which a propeller operates as well as its aerodynamic and dynamic response to this unsteady environment. Methods are presented for predicting and net thrust of a propeller-wing-body combination as well as the unsteady thrust and torque acting on the propeller. Sample calculations as well as wind tunnel and flight test results are presented which illustrate the sensitivity of a propeller to the flow field in which it is operating.

Mccormick, B. W.↗
NASA NTRS1979

The analysis of propellers including interaction effects

Analytical and experimental studies have been undertaken on propellers operating in the unsteady flow field produced by interaction effects due to the fuselage, wing, and nacelles. Methods have been developed and verified experimentally for determining the velocity field in which a propeller operates as well as its aerodynamic and dynamic response to this unsteady environment. Methods are presented for predicting the net thrust of a propeller-wing-body combination as well as the unsteady thrust and torque acting on the propeller. Sample calculations as well as wind tunnel and flight test results are presented which illustrates the sensitivity of a propeller to flow field in which it is operating.

Mccormick, B. W.↗
NASA NTRS1981

Propeller propulsion integration, phase 1

A bibliography was compiled of all readily available sources of propeller analytical and experimental studies conducted during the 1930 through 1960 period. A propeller test stand was developed for the measurement of thrust and torque characteristics of full scale general aviation propellers and installed in the LaRC 30 x 60 foot full scale wind tunnel. A tunnel entry was made during the January through February 1980 period. Several propellers were tested, but unforseen difficulties with the shaft thrust torque balance severely degraded the data quality.

Bennett, G.↗
NASA NTRS1923

Tests on air propellers in yaw

This report contains the results of tests to determine the thrust (pull) and torque characteristics of air propellers in movement relative to the air in a line oblique to the line of the shaft, and specifically when such angle of obliquity is large, as in the case of helicopter flight with the propeller serving for both sustentation and traction.

Durand, W F↗
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 NTRS1987

Analytical determination of propeller performance degradation due to ice accretion

A computer code capable of computing the propeller performance for clean, glaze, or rime ice propeller configurations to determine the performance degradation resulting from a given icing encounter has been developed. The inviscid, incompressible flowfield at each specified propeller radial location is first computed using the Theodorsen method. A droplet trajectory computation then calculates the droplet impingement points and airfoil collection efficiency for each radial location. User-selectable empirical correlations are available for determining the aerodynamic penalties due to ice accretion. Propeller performance is finally computed using strip analysis for either the clean or iced propeller. In the iced mode, the thrust and torque coefficient equations are modified by the drag and lift coefficient increments due to ice to obtain the appropriate iced values. Comparison with available experimental propeller icing data shows generally good agreement. The code's capability of properly predicting the thrust coefficient, power coefficient, and propeller efficiency of an iced propeller is shown to be dependent on the choice of empirical correlation employed as well as on the proper specification of the radial icing extent and propeller blade angle.

Miller, T. L.↗