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Tuesday, July 28, 2020 | History

1 edition of Estimation of Rotor Blade Torsional Deformations from Measured Blade Torsion Moments found in the catalog.

Estimation of Rotor Blade Torsional Deformations from Measured Blade Torsion Moments

Estimation of Rotor Blade Torsional Deformations from Measured Blade Torsion Moments

  • 127 Want to read
  • 34 Currently reading

Published by Storming Media .
Written in English

    Subjects:
  • TEC031000

  • The Physical Object
    FormatSpiral-bound
    ID Numbers
    Open LibraryOL11845476M
    ISBN 101423509811
    ISBN 109781423509813

    Torsion: twisting of a structural member, when it is loaded by couples that produce rotation about its longitudinal axis T1 = P1 d1 T2 = P2 d2 the couples T1, T2 are called torques, twisting couples or twisting moments unit of T: N-m, lb-ft in this chapter, we will develop formulas for the stresses and deformations . 2. Differential Equation of Torsional Blade Vibrations .. 58 3. Determination of the Natural Torsional Blade Vibration Modes and Frequencies .. 60 4. Determination of the Natural Vibration Modes and Frequencies of a Rotor as a Whole .. 64 Section 6. Combined Flexural and Torsional Blade .

      A novel sensor network for measuring rotorcraft blade elastic twist in flight using an expansion of strain gage theory is proposed and demonstrated. The embedded sensor has neglig. blade is idealized as an Euler–Bernoulli beam in bending and a rod in torsion. The theory is rigorously derived from first principles and shows that a sawtooth shaped sensor will measure twist directly without any numerical integration. The network is modeled computationally for a blade undergoing arbitrary torsional and bending moments.

      The ability to photogrammetrically measure blade deflection during wind tunnel testing was successfully demonstrated. The deformation of small-scale rotating blade was measured using DIC system (Lawson and Sirohi, ). A commercial DIC software was used to obtain bending and twist on three different types of rotors with varying flexibility. Rotor-blade coupled torsional frequencies of the model rotor based on the FEM based quasi-modal technique were compared with a complete FEM analysis of the model rotor. Both methods gave results in good agreement. We also compared the frequencies measured through rotation testing of the model rotor to calculations.


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Estimation of Rotor Blade Torsional Deformations from Measured Blade Torsion Moments Download PDF EPUB FB2

ESTIMATION OF ROTOR BLADE TORSIONAL DEFORMATIONS FROM MEASURED BLADE TORSION MOMENTS Ronald S. Volkin Captain, U.S. Army B.S., Embry-Riddle Aeronautical University, Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN AERONAUTICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL March Enter the password to open this PDF file: Cancel OK.

File name:. Estimation of rotor blade torsional deformations from measured blade torsion moments. method is applied to estimate rotor blade torsional deflections. The SPA technique requires calculated mode shapes for the tested rotor blade and strain measurements from the rotor's wind tunnel or flight test.

The Holzer method is developed to calculate Author: Ronald S. Volkin. By comparing the recorded cross sections with a CAD model of the rotor blade, the deformations in out-of-plane and torsional direction can be derived.

Discover the world's research 17+ million members. By comparing the recorded cross sections with a CAD model of the rotor blade, the deformations in out-of-plane and torsional direction can be derived. View full-text Conference Paper. rotor torsional oscillatio ns is then achieved by using.

the in-plane bending moments at the blade bases. develops a generator torque demand from an estimate of the main rotor shaft. Measured airloads and blade bending moments are obtained from a model scale UHA BLACK HAWK rotor.

Test conditions selected for this study include cases in which blade. The calculated blade flap and chord bending and torsion moments were compared with the flight and wind tunnel measurements. The calculations have been conducted with the identical analysis options for all rotors (Ref. 12).

Blade Natural Frequencies The blade natural frequencies were calculated from 40% to % of the nominal rotor speed and. By modeling the complete rotor and taking blade elasticity into account, it is demonstrated that the torsional natural frequencies of a complete rotor-blade model can also become speed dependent.

First, a stiff rotor blade of known geometry was tested and its shape as measured by DIC was compared to the shape of the mold from which it was made. At a constant radial station, DIC measurements of the surface height of the rotor blade were compared to measurements from a LDS mounted in close proximity to the spinning rotor.

The rotor blade deformation measured by DIC is examined in this section. Fig. 12 shows the flap bending deformation of the rotor blade at 0° and 30° root pitch angle, at RPM over one revolution.

Note that images were continuously taken over revolutions at 16 evenly-spaced azimuthal locations, yielding images per camera at each. The test cases considered in this section refer to hingeless rotor blades whose equivalent structural properties resemble those of the Bölkow (now Airbus Helicopters) BO helicopter blades, with a radius of m rotating at rad/s, either in hover or in forward-flight at an advance ratio of μ = The first blade model analyzed is uniform, whereas the second one is strongly non.

elastic rotor blades coupled to a rigid helicopter fuselage. The key feature in UMARC is the use of an FE methodology, which can accurately model the kinematics and elastic behavior of the rotating blade.

The rotor blade is assumed to be an elastic beam undergoing flap bending, lag bending, elastic twist, and axial deflections. the blade caused by aerodynamic pitching moments is the key mechanism here, the torsional stiffness of the blade is a key parameter affecting the authority of aerodynamic moments.

The current study investigates the effects of blade torsion frequencies on rotor performance improvement of a four-blade articulated rotor with trailing edge flaps. Estimation Of Rotor Blade Torsional Deformations From Measured Blade Torsion Moments - Mar 2, by Ronald S. Volkin; ULTIMATE INTERACTIVE BASIC TRAINING WORKBOOK, THE: What You Must Know to Survive and Thrive in Boot Camp [Paperback.

span of the rotor, and even worse will cause the rotor broken. So the torsional vibration of rotor has aroused the attentions of the electricity production and the manage-ment departments widely [3,4].

Calculating the characteristics of rotor torsional vibra-tion. Table 1: Tested results for the tail rotor blade Type of the blade Tail rotor Type of core polyurethane foam Elastic axis position, x/c Average values of torsional stiffness mQm [daN m/rad] Average values of flexional stiffness mdm [daN m/rad] first mode f 1 [Hz] second mode f 2 [Hz] third mode f 3 [Hz] fourth.

The structural properties of Higher harmonic Aeroacoustic Rotor Test (HART I) blades have been measured using the original set of blades tested in the wind tunnel in A comprehensive rotor dynamics analysis is performed to address the effect of the measured blade properties on airloads, blade motions, and structural loads of the rotor.

This paper proposes a Nonlinear Model Predictive Controller (NMPC) for pitch control of Horizontal-Axis Wind Turbines (HAWTs) in Region 3 to avoid flu. rotor loads measured on a variety of different heh­ copters.

Similarities observed in the rotor l~ading ~or these different aircraft, then, represent the basIc physIcs of the rotor loads problem and hence provide a good first test for the comprehensive methods.

The focus of the present paper is the prediction of blade torsional loading. torsional mode shapes of the blade. The present paper has two goals. The first objective is to demon-strate how an aeroelastic analysis with two degrees offreedom (flap bending and twist), and whose equations are truncated consistently with an ordering scheme, can accurately predict the deformations of a rotor blade with negligible torsional.the sensitivity of overall blade vibration characteristics to torsional oscillations was also investigated from the equations of motion for the sample blade.

the illustrated results show the importance of torsional degrees-of-freedom in analysis. various possibilities of .The following moments and forces per unit length of rotor blade, which produce the moments about the feathering hinge, are acting on the blade section: 1.

Centrifugal force 2 cos ωθmxm acting at a distance y about the feathering hinge. 2. Linear torsion moments: inertia moment mxmmy cosθ+θJ, where 2 JJ mxθ=+mm, propeller moment J 2 sin cos.