A Coupled Helicopter Rotor/Fuselage Dynamics Model Using Finite Element Multi-body

Cheng, Qu; Zhu, Yan; Feng, Zhizhuang; Quanlong, Chen

doi:10.1051/matecconf/20167701016

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…15). Cheng et al 17) clarifies that main rotor natural frequencies coupled with a fuselage are almost the same as those in the decoupled analysis. Therefore, the natural frequencies can be considered to be the main rotor natural frequencies coupled with the fuselage.…”

Section: Mrh Vibration Forces and Momentsmentioning

confidence: 85%

Analysis of Rotorcraft Vibration Reduction Using a Center-of-Gravity Offset

YOSHIZAKI

Sunada

2023

Trans. Japan Soc. Aero. S Sci.

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When a rotorcraft has N blades, N/rev vibration becomes large as the cruise speed increases. This article numerically examines the effect of Center-of-Gravity (CG) offset on rotorcraft vibration. A mid-sized rotorcraft, SH-60K, was selected for analysis with the use of CAMRAD II. A minimum of 60% decrease in the baseline z-acceleration was achieved at the pilot seat, which dominantly defines the vibration circumstance at a large offset CG. There exists a middle CG location between the baseline and the vibration minimum CG, where both the main rotor power characteristics and the trim attitudes are allowable. At that point, an approximately 20% reduction in the z-acceleration at the pilot seat can be achieved. Not only for preexisting helicopters, but also for rotorcraft in development, engineers should keep in mind that the CG positions are worth investigating to reduce vibration; although, the CG positions in almost all rotorcraft have been directly below the main rotor hub.

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Section: Mrh Vibration Forces and Momentsmentioning

confidence: 85%

Analysis of Rotorcraft Vibration Reduction Using a Center-of-Gravity Offset

YOSHIZAKI

Sunada

2023

Trans. Japan Soc. Aero. S Sci.

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“…A growing number of publications [1][2][3][4][5] focusing on the influence of fuselage on the helicopter rotor aerodynamcis demonstrate the importance of the subject. Recently, due to increasingly stringent International Civil Aviation Organization (ICAO) requirements on the permissible noise levels produced by aircrafts, including helicopters, the focus of research has shifted from rotor aerodynamics to the acoustics generated by the rotor in the presence of fuselage [6][7][8][9]. The simulation of the acoustics of the entire helicopter including the fuselage presents a challenge as it requires substantial computational resources and efficient parallel algorithms.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Fuselage Impact on Acoustic Characteristics of a Helicopter Rotor

2022

JSFI

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The paper presents the results of the simulation of unsteady turbulent flow generated by helicopter main rotor in the presence of the fuselage with an emphasis on the analysis of the influence of the fuselage on the rotor-induced flow and the rotor-generated acoustic field. The Reynolds-averaged Navier-Stokes equations with the Spalart-Allmaras turbulence model are used to simulate the Caradonna-Tung rotor and ROBIN fuselage interaction in hovering flight. The governing equations are discretized using the vertex-centered control volume method on mixedelement unstructured meshes with the sliding mesh technology to treat the rotor. The acoustic field generated by the rotor+fuselage interaction is comparatively analyzed against the case of an isolated rotor. It is found that the presence of fuselage significantly changes the rotor-generated acoustics. In particular, the presence of the fuselage noticeably distorts the directivity of acoustic radiation and increases the overall sound pressure level under the fuselage up to 20 dB, emphasizing the importance of the influence of fuselage on the helicopter acoustics.

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“…A coupled rotor/fuselage based on FEM [31] and FEM-transfer matrix method [32], finite element multibody system [33,34], coupled rotor/fuselage analysis based on elastic blade/flexible fuselage modeling (stick model) [35], and coupled rotor/flexible fuselage model for vibration reduction studies using 3D frame models [36] and using software MSC.ADMAS and MSC. NASTRAN [37] are discussed in detail.…”

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confidence: 99%

Flapwise Vibration Computations of Coupled Helicopter Rotor/Fuselage: Application of Multibody System Dynamics

et al. 2018

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Natural vibration characteristics of rotating blades are of fundamental importance from the viewpoint of maneuvering, blade life, vibration levels, aeroelastic, and stability. Helicopters may have serious resonant vibration problems when the excitation frequencies are equal to some multiple of the rotational speed. To ensure that conditions susceptible to resonance do not exist within the range of operating speeds, it is necessary that the natural frequencies and mode shapes be determined accurately. On one hand, as the complexity of multibody systems and the methods used for their design and control increases, the need for more elegant formulations of the equations of motion becomes an issue of paramount importance. On the other hand, although processor speed has increased dramatically over the last decade, development of computationally efficient algorithms is still a major issue in multibody dynamics. The transfer matrix method for multibody systems (MSTMM) accounts for both aspects. Based on many advantages of MSTMM in studying multibody system dynamics, a scenario of dynamics coupling between the flexible twin blade rotor and flexible fuselage of a typical helicopter model is proposed. The dynamical model of the coupled system, its topological figure, the overall transfer equation, and the characteristics equation are developed. The flapwise vibrations characteristics are carried out to obtain uncoupled/coupled twin blade/fuselage system natural modes and frequencies as a function of rotor speed. Examples are performed to validate with those published in the literature and produced by Workbench ANSYS.

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A Coupled Helicopter Rotor/Fuselage Dynamics Model Using Finite Element Multi-body

Cited by 4 publications

References 8 publications

Analysis of Rotorcraft Vibration Reduction Using a Center-of-Gravity Offset

Analysis of Rotorcraft Vibration Reduction Using a Center-of-Gravity Offset

Numerical Study of Fuselage Impact on Acoustic Characteristics of a Helicopter Rotor

Flapwise Vibration Computations of Coupled Helicopter Rotor/Fuselage: Application of Multibody System Dynamics

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