Semi-empirical modeling of fuselage–rotor interference for comprehensive codes: the fundamental model

Wall, Berend G. van der; Bauknecht, André; Jung, Sung Nam; You, Young H.

doi:10.1007/s13272-014-0113-4

Cited by 8 publications

(9 citation statements)

References 27 publications

(45 reference statements)

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“…Other notable work where the aerodynamic influence of the fuselage has been included in nonlinear predictions of airloads, aeroelastic blade deformations, and rotor trim using a coupled CFD/CSD approach, includes that of Boyd (20) , Sa et al (21) , Smith et al (22) , and Van der Wall et al (23) .…”

Section: Helicopter Rotor-fuselage Aerodynamic Interactionmentioning

confidence: 99%

“…This implicit coupling in the roll-yaw equations may lead to an instability during nonlinear control response simulation where Equations (20)-(28) need to be continuously integrated numerically in the time-domain. This instability appears due to accumulating numerical errors in the time-integration of Equations (23) and (25). This effect manifests when the employed values of p .…”

Section: Rigid Body Fuselage Kinematicsmentioning

confidence: 99%

“…in the RHS of Equations (23) and (25) at time = t are obtained from the previous time-step (t -Δt), when in fact they refer to the present values (t) that are effectively unknown. Hence, Equations (23) and (25) are re-formulated in order to mitigate the implicit coupling between the roll-yaw DOFs and re-derive a set of equations that are essentially free of such numerical instabilities. This process is carried out by expressing Equations (23) and (25)…”

Section: Rigid Body Fuselage Kinematicsmentioning

confidence: 99%

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Modelling the aeroelastic response and flight dynamics of a hingeless rotor helicopter including the effects of rotor-fuselage aerodynamic interaction

Goulos

2015

Aeronaut.j.

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This paper presents a mathematical approach for the simulation of rotor-fuselage aerodynamic interaction in helicopter aeroelasticity and flight dynamics applications. A Lagrangian method is utilised for the numerical analysis of rotating blades with nonuniform structural properties. A matrix/vector-based formulation is developed for the treatment of elastic blade kinematics in the time-domain. The combined method is coupled with a finite-state induced flow model, an unsteady blade element aerodynamics model, and a dynamic wake distortion model. A three-dimensional, steady-state, potential flow, source-panel method is employed for the prediction of induced flow perturbations in the vicinity of the fuselage due to its presence in the free-stream and within the rotor wake. The combined rotor-fuselage model is implemented in a nonlinear flight dynamics simulation code. The integrated approach is deployed to investigate the effects of rotor-fuselage aerodynamic interaction on trim performance, stability and control derivatives, oscillatory structural blade loads, and nonlinear control response for a hingeless rotor helicopter modelled after the Eurocopter Bo105. Good agreement is shown between flow-field predictions and experimental measurements for a scaled-down isolated fuselage model. The proposed numerical approach is shown to be suitable for real-time flight dynamics applications with simultaneous prediction of structural blade loads, including the effects of rotor-fuselage aerodynamic interaction. NOMENCLATURE B jinfluence coefficient of the jth source panel element on the evaluation point with co-ordinates (x, y, z) m C, D wake curvature influence matrix (Krothapalli and Zhao models, respectively) g gravitational constant, m/sec 2 I xx , I yy , I zz , I xz Fuselage roll, pitch, yaw, and roll-yaw moments of inertia, kg . m 2 K Re wake curvature parameter L c , L s Cosine and sine inflow gain matrices M c , M s Cosine and sine apparent mass matrices n unit vector perpendicular to dS of S b positive towards the direction of the potential jump, m N b , N p number of blades and quadrilateral panel elements p, q, r angular velocity components of the fuselage expressed about the fuselage reference axes frame, rad/sec P rotor main rotor power required, kW P _ n m (ν) normalised associated Legendre function of first kind P(x, y, z) induced potential evaluation point with Cartesian co-ordinates (x, y, z) q _ , p _ normalised pitch and roll rates = , r geometric distance of source panel from evaluation point P(x, y, z), m r, R local and total rotor blade radius, m r _ non-dimensional radial co-ordinate on the rotor disk = S state of wake spacing, = 2πV T S b three-dimensional body surface, m 2 t time, sec t _ non-dimensional time = Ωt V, V T flow parameter and total flow at the rotor disk plane, dimensionless V flight helicopter flight speed, m/sec u _ , v _ , w _ normalised fuselage induced velocity perturbations v induced velocity perturbation vector = [u v w] T , ms -1 V c , V s Cosine and sine mass flow parameter mat...

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Section: Helicopter Rotor-fuselage Aerodynamic Interactionmentioning

confidence: 99%

Section: Rigid Body Fuselage Kinematicsmentioning

confidence: 99%

Section: Rigid Body Fuselage Kinematicsmentioning

confidence: 99%

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Modelling the aeroelastic response and flight dynamics of a hingeless rotor helicopter including the effects of rotor-fuselage aerodynamic interaction

Goulos

2015

Aeronaut.j.

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“…Due to this method no flow separation takes place and potential theory-like flow fields are obtained. This paper builds up on former publications regarding the fundamental model at the example of the HART II model fuselage for zero angle of attack and no side-slip [42] and the influence of angle of attack without side-slip at the example of the Bo105 fuselage [43] and fuselages used by NASA in the Ames full-scale aerodynamics complex and by DLR in the large low-speed facility of the DNW [44]. The focus presented here is the investigation of the influence of side-slip angles.…”

Section: Introduction and Objectivesmentioning

confidence: 99%

Semi-empirical modeling of fuselage–rotor interference for comprehensive codes: influence of side-slip angle

Wall

Yin

2016

CEAS Aeronaut J

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A semi-empirical and physics-based analytical formulation of the induced velocities generated by the fuselage shell of the Bo105 wind tunnel model in the volume around the rotor is derived from velocity data computed by a panel code. The reduced-order analytical model is several orders of magnitude faster than the panel code and thus is predestinated for use in comprehensive rotor codes. Angle of attacks investigated include vertical descent, shallow descent, level flight and climb to vertical ascent. Side-slip angles range from forward to quartering flight. The analytical induced velocity model can be directly used to account for the inflow at the blade elements and also allows for analytical or numerical integration of rotor wake convection to compute the associated displacements of rotor blade tip vortices travelling downstream within this velocity field. This model will be used to replace a fully panelized fuselage (and thus significantly reduce the computational effort) throughout a simulation with an aeromechanics code to account for the influence of the fuselage (e.g., in a design stage). The usage within an aerodynamics code (e.g., a panel code) reduces the panelization to the rotor blades only, leaving the computation of the fuselage-induced velocities to the model. The focus of this paper is the analytical evaluation of fuselagerotor interference in side-slip angles on rotor trim controls, using blade element momentum theory. The results are compared to the influence of thrust-induced inflow gradients on rotor trim.

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“…It would exceed the scope of this paper to outline a review of all this work, and a comprehensive overview is found in Ref. 7. Rotorcraft interactional aerodynamics has been one of the key research concerns for the design, performance, handling qualities, vibration, and aero-acoustic radiation.…”

Section: Introductionmentioning

confidence: 99%

A model for real-time computation of fuselage-rotor interference

Wall¹,

Yin²

2017

Int. J. Model. Simul. Sci. Comput.

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A simple analytical real-time capable model to account for fuselage-induced velocities at rotor blade elements is described at the example of the Bo105 fuselage. Data of the fuselage-induced flow fields in the volume of rotor operation above the fuselage are first computed by a panel method in the range of angle of attack and sideslip of ±90 • . The model parameters are then estimated based on these data. The usefulness of the model in combinations of angle of attack and sideslip is demonstrated.

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Semi-empirical modeling of fuselage–rotor interference for comprehensive codes: the fundamental model

Cited by 8 publications

References 27 publications

Modelling the aeroelastic response and flight dynamics of a hingeless rotor helicopter including the effects of rotor-fuselage aerodynamic interaction

Modelling the aeroelastic response and flight dynamics of a hingeless rotor helicopter including the effects of rotor-fuselage aerodynamic interaction

Semi-empirical modeling of fuselage–rotor interference for comprehensive codes: influence of side-slip angle

A model for real-time computation of fuselage-rotor interference

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