Lagrangian formulation for the rapid estimation of helicopter rotor blade vibration characteristics

Goulos, Ioannis; Pachidis, Vassilios; Pilidis, Pericles

doi:10.1017/s000192400000960x

Cited by 22 publications

(29 citation statements)

References 21 publications

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“…The aeroelastic rotor model integrated in HECTOR is based on the numerical method described in [5,12] for the simulation of rotor blade elasticity in the time domain. Non-linear inertial terms associated with large blade deflections as well as the helicopter 3-dimensional motion are accounted.…”

Section: Aeroelastic Rotor Modelmentioning

confidence: 99%

Impact of Adverse Environmental Conditions on Rotorcraft Operational Performance and Pollutant Emissions

Ortiz-Carretero

Pardo

Goulos

et al. 2017

Journal of Engineering for Gas Turbines and Power

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It is anticipated that the contribution of rotorcraft activities to the environmental impact of civil aviation will increase in the future. Due to their versatility and robustness, helicopters are often operated in harsh environments with extreme ambient conditions. These severe conditions, not only affect the performance of the engine, but also the aerodynamics of the rotorcraft. This impact is reflected in the fuel burn and pollutants emitted by the rotorcraft during a mission. The aim of this paper is to introduce an exhaustive methodology to quantify the influence adverse environment conditions have in the mission fuel consumption and the associated emissions of nitrogen oxides (NO x ). An Emergency Medical Service (EMS) and a Search and Rescue (SAR) mission are used as case studies to simulate the effects of extreme temperatures, high altitude, and compressor degradation on a representative Twin-Engine Medium (TEM) weight helicopter, the Sikorsky UH-60A Black Hawk. A simulation tool for helicopter mission performance analysis developed and validated at Cranfield University was employed. This software comprises different modules that enable the analysis of helicopter flight dynamics, powerplant performance and exhaust emissions over a user defined flight path profile. For the validation of the models implemented, extensive comparisons with experimental data are presented throughout for rotorcraft and engine performance as well as NO x emissions. Reductions as high as 12% and 40% in mission fuel and NO x emissions, respectively, were A Main rotor disk area [m 2 ] C p =P MR /ρA(ΩR) 3 Power coefficient [-] C t = T MR /ρA(ΩR) 2 Thrust coefficient [-] P MR Main rotor power [W] R Main rotor radius [m] T MR Main rotor thrust [N] V Air speed [m/s] V NOx Airspeed for minimum NO x [m/s] V rg Airspeed for maximum range [m/s] w f Powerplant fuel flow [g/s] w NOx Powerplant NO x production [g/s] Greek symbols Γ Mass flow capacity [-] Δ Increment [%] Ω Main rotor rotational speed [rad/s] η Isentropic efficiency [-] ρ Air density [kg/m 3 ] σ Main rotor solidity [-] ω Blade natural frequency [rad/s]

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Section: Aeroelastic Rotor Modelmentioning

confidence: 99%

Impact of Adverse Environmental Conditions on Rotorcraft Operational Performance and Pollutant Emissions

Ortiz-Carretero

Pardo

Goulos

et al. 2017

Journal of Engineering for Gas Turbines and Power

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“…Lagrange equation is usually used to build dynamic equations of mechanism [6][7][8], it can analyze the dynamic characteristics by defining generalized force and generalized coordinates. The dynamic equations deduced from Lagrange equation can avoid constraint reaction and reduce solving difficulty.…”

Section: Mathematical Modelmentioning

confidence: 99%

Influence of installation deviation on dynamic performance of synchronous magnetic coupling

Zhang¹,

Liu²,

Li³

et al. 2017

Vib. proced.

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Abstract. To improve dynamic characteristics of synchronous magnetic coupling, this paper mainly analyzed the influence of the installation deviation on the synchronous magnetic coupling's dynamic performance used in the horizontal axis wave energy power generation device. Dynamic characteristics equations based on Lagrange equation are built in the paper to analyze the dynamic characteristic of synchronous magnetic coupling. The radial deviation, the angle deviation and the center-of-mass deviation are considered in the equation. The influence of those installation deviations on the synchronous magnetic coupling performance is analyzed based on the mathematical model. The results show that the rise time, the overshoot, the peak time, the adjusting time and the oscillation of the synchronous magnetic coupling are almost not affected by those installation deviations.

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“…It is shown in Ref. 41 that, this approach leads to considerable savings in computational time since the calculated modal frequencies converge rapidly to definitive values using only a small number of assumed functions. This is due to them originating in classical theories which renders them excellent candidates for deployment in any method based on the principle of virtual work.…”

Section: Theoretical Development 21 Natural Vibration Characteristicmentioning

confidence: 99%

Flexible rotor blade dynamics for helicopter aeromechanics including comparisons with experimental data

2015

Self Cite

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This paper presents the development of a mathematical model for the implementation of flexible rotor blade dynamics in real-time helicopter aeromechanics applications. A Lagrangian approach is formulated for the rapid estimation of natural vibration characteristics of nonuniform rotor blades. A matrix/vector formulation is proposed for the treatment of elastic blade kinematics in the time-domain. In order to overcome the classical hurdles of time-accurate simulation and establish applicability in real-time, a novel, second-order accurate, finite-difference scheme is employed for the numerical discretisation of elastic blade motion. The proposed rotor dynamics model is coupled with a finite-state induced flow and an unsteady blade element aerodynamics model. The combined formulation is implemented in a helicopter flight mechanics simulation code. The integrated approach is deployed in order to investigate rotor blade resonant frequencies, trim control angles, oscillatory blade loads and induced vibration for a hingeless and an articulated helicopter rotor. Extensive comparisons are carried out with wind tunnel and flight test measurements, and non-real-time comprehensive analysis methods. Good agreement with measured data is exhibited considering primarily the low-frequency harmonic components of oscillatory loading. It is shown that, the developed methodology can be utilised for real-time simulation on a typical computer with sufficient modelling fidelity for accurate estimation of oscillatory blade loads.

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Lagrangian formulation for the rapid estimation of helicopter rotor blade vibration characteristics

Cited by 22 publications

References 21 publications

Impact of Adverse Environmental Conditions on Rotorcraft Operational Performance and Pollutant Emissions

Impact of Adverse Environmental Conditions on Rotorcraft Operational Performance and Pollutant Emissions

Influence of installation deviation on dynamic performance of synchronous magnetic coupling

Flexible rotor blade dynamics for helicopter aeromechanics including comparisons with experimental data

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