Aeroelastic response of helicopters with flexible fuselage modeling

Vellaichamy, Senthilvel; Chopra, Inderjit

doi:10.2514/6.1992-2567

Cited by 8 publications

(5 citation statements)

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“…The detailed derivation process can be found in references. 6,20 The dynamic equations of the rotor-fuselage coupled system are obtained using the Hamilton variational principle, as follows:…”

Section: Rotor/fuselage Coupling Dynamic Equationmentioning

confidence: 99%

CFD-CSD method for coupled rotor-fuselage vibration analysis with free wake-panel coupled model

Wang

Jing

Yun

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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An efficient comprehensive vibration analysis method for a helicopter rotor–fuselage coupling system is presented. This loose computational fluid dynamics (CFD)/computational structural dynamics (CSD) coupling approach with a free wake–panel coupled model is used for system vibration response analysis. The CSD model of the helicopter consists of a fuselage model using a refined three dimensional (3 D) finite element model (FEM) and a rotor model consisting of nonlinear moderate deflection beam elements with 15 degrees of freedom. The unsteady Euler CFD solver is used for the flow field analysis of the entire vehicle. The induced inflow of the quasi-steady aerodynamic force is calculated with the free wake–panel coupled model, which is used to simulate rotor–fuselage aerodynamic interference. Using a full-scale helicopter as an example, the vibration responses of the typical fuselage position in hovering and level flights are analysed. When compared with the literature results and flight test data, the predictions of the proposed method are closer to the test data than those of the traditional method in hovering and low forward ratio flights, and the difference between the two methods is minimal in high forward ratio flight.

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Section: Rotor/fuselage Coupling Dynamic Equationmentioning

confidence: 99%

CFD-CSD method for coupled rotor-fuselage vibration analysis with free wake-panel coupled model

Wang

Jing

Yun

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Note the close parallel between Herting's transformation for displacements and velocities, eqs. (8) and (33), respectively. Although Herting's transformation, eq.…”

Section: Kinetic Energymentioning

confidence: 99%

“…[7]) studied the dynamic response of a rotor/rigid fuselage system subjected to a three-dimensional gust. References [8,2] derived a comprehensive set of rotor-body equations for the analysis of the Bell AH-1G helicopter. Many of these approaches assume small amplitude rigid body motions of the fuselage, rendering them inapplicable to large angle maneuver flights.…”

Section: Introductionmentioning

confidence: 99%

Coupled Rotor-Fuselage Analysis with Finite Motions Using Component Mode Synthesis

Bauchau¹,

Rodriguez²,

Chen³

2004

j am helicopter soc

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This paper is concerned with the modeling of a rotor-fuselage system undergoing large angle maneuvers. The behavior of the elastic fuselage will be represented by a modal approximation, thereby greatly reducing the computational cost of the simulation. In this work, a floating frame approach is used. The total motion of the fuselage consists of the superposition of the rigid body motions of the floating frame and of elastic motions that are assumed to remain small. The proposed formulation makes use of a component mode synthesis technique that leaves the analyst free to choose any type of modal basis and simplifies the connection of the fuselage to other rotorcraft components. The proposed formulation is independent of the finite element analysis package used to compute the modes of the fuselage. It is also shown that in the absence of elastic deformations, the formulation recovers the exact equations of motion for a rigid body.

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“…14,22,23 Such orderingschemes have been also used in other similar studies involving coupled rotor/ exible fuselage dynamics. 15,16 The ordering scheme is based on the assumption that…”

Section: Rotor Modelmentioning

confidence: 99%

“…Other studies have represented the coupled rotor/ exible fuselage model by a one-dimensional beam, where the beam itself is modeled using a number of discrete beamtype nite elements. 15,16 Again, the important role of nonstructural masses in accurately simulating the frequency content of the coupled rotor/ exible fuselage system was not addressed in Refs. 15 and 16.…”

mentioning

confidence: 98%

Coupled Helicopter Rotor/Flexible Fuselage Aeroelastic Model for Control of Structural Response

2000

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A re ned coupled rotor/ exible fuselage aeroelastic response model is developed for vibration reduction studies based on active control of structural response (ACSR). The structural model is capable of representing exible, hingeless rotors combined with a exible fuselage, and a rigid platform combined with the actuators required for modeling the ACSR system and is combined with a free wake model. The in uence of rotor/fuselage coupling and improved aerodynamics on the vibratory hub loads is investigated. Nomenclature A= beam cross-sectional area a NbC , a Nb S = cosine and sine parts of acceleration at various fuselage locations a z = fuselage vertical acceleration at various locations C d0 = blade drag coef cient C O , C I , C NW = matrices of induced velocity in uence coef cients C W = helicopter coef cient of weight c = blade chord D = wake distortion E = Young's modulus of elasticity E I y , E I z = blade bending stiffnesses in ap and lead-lag= blade aerodynamic, gravitational, and inertial forces F b0 , F bnc , F bns = Fourier coef cients of blade equations of motion F e0 , F enc , F ens = Fourier coef cients of elastic fuselage equations of motion F fus = total fuselage forces F NbC , F Nb S = cosine and sine parts of rotor hub forces F r0 , F rnc , F rns = Fourier coef cients of fuselage rigid body equations of motion F T , M T = tail rotor thrust and moment F x , F y , F z = vibratory hub shear components F 0 , M 0 = constant part of rotor hub loads f C d f = fuselage equivalent at plate drag area G J = blade torsional stiffness [I ] = fuselage inertia tensor I p = polar moment of inertia I x , I y , I z = fuselage beam cross-sectional principal moment of inertia J = beam torsional constant L = Lagrangian M = fuselage total mass M A b , M G b , M I b = blade aerodynamic, gravitational, and inertial moment M fus = total fuselage moments M Nb C , M Nb S = cosine and sine parts of hub moments M ns = nonstructural consistent mass matrix M x , M y , M z = vibratory hub moment components m b = blade mass distribution per unit length N = matrix of shape functions for calculation of nonstructural mass matrix N b = number of blades N H , N el , N rg = number of harmonics retained in Fourier expansion of blade, fuselage elastic, and rigid body degrees of freedom Q i = fuselage generalized force q = response vector q b , q e , q r = vectors of blade, fuselage elastic, and rigid body degrees of freedom q b0 , q bnc , q bns = Fourier coef cients of blade response q e0 , q enc , q ens = Fourier coef cients of fuselage elastic response q r0 , q rnc , q rns = Fourier coef cients of fuselage rigid body response R = rotor radius R x , R y , R z = fuselage rigid body translational degrees of freedom R 0 = fuselage center of mass position in inertial frame r b = position of rotor blade point r w = position of wake element r 0 = undeformed position of fuselage point with respect to the fuselage center of mass in fuselage reference frame r 0 = deformation of fuselage point in fuselage reference frame T = kinetic energy U e = e...

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Aeroelastic response of helicopters with flexible fuselage modeling

Cited by 8 publications

References 0 publications

CFD-CSD method for coupled rotor-fuselage vibration analysis with free wake-panel coupled model

CFD-CSD method for coupled rotor-fuselage vibration analysis with free wake-panel coupled model

Coupled Rotor-Fuselage Analysis with Finite Motions Using Component Mode Synthesis

Coupled Helicopter Rotor/Flexible Fuselage Aeroelastic Model for Control of Structural Response

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