Validation of Rotorcraft Flight Simulation Program through Correlation with Flight Data for Soft-in-Plane Hingeless Rotors

Staley, J. A.

doi:10.21236/ada021176

Cited by 19 publications

(14 citation statements)

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“…The rotor design characteristics have been thoroughly described in Ref. [32], A total of eight inflow harmonics are employed in order to capture the effect of higher harmonic loading on the inflow response. The radial inflow expan sion polynomials used, reach up to the tenth power of nondimensional rotor radius.…”

Section: Resultsmentioning

confidence: 99%

“…[35], Figure 2 presents the calculated resonance chart for the rotor blades of the Bo 105 helicopter. Simulation results from Boeing-VertoTs simulation program Y-71 [32] for flap, lag, and torsion natural fre quencies at nominal rotorspeed are also included for comparison. The frequency predictions from Y-71 have been extracted from Ref.…”

Section: Resultsmentioning

confidence: 99%

“…The frequency predictions from Y-71 have been extracted from Ref. [32]. Boeing-Vertol Y-71 essentially calculates elastically and inertially coupled modes for F/L/T.…”

Section: Resultsmentioning

confidence: 99%

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Real-Time Aero-elasticity Simulation of Open Rotors With Slender Blades for the Multidisciplinary Design of Rotorcraft

Goulos

Pachidis

2014

Journal of Engineering for Gas Turbines and Power

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This paper elaborates on the theoretical development of a mathematical approach, tar geting the real-time simulation of aero-elasticity for open rotors with slender blades, as employed in the majority of rotorcraft. A Lagrangian approach is formulated for the rapid estimation of natural vibration characteristics of rotor blades with nonuniform structural properties. Modal characteristics obtained from classical vibration analysis methods are utilized as assumed deformation functions. Closed form integral expressions are incorporated, describing the generalized centrifugal forces and moments acting on the blade. The treatment of three-dimensional elastic blade kinematics in the timedomain is thoroughly discussed. In order to ensure robustness and establish applicability in real time, a novel, second-order accurate, finite-difference scheme is utilized for the temporal discretization of elastic blade motion. The developed mathematical approach is coupled with a finite-state induced flow model, an unsteady blade element aerodynamics model, and a dynamic wake distortion model. The combined formulation is implemented in an existing helicopter flight mechanics code. The aero-elastic behavior of a full-scale hingeless helicopter rotor has been investigated. Results are presented in terms of rotor blade resonant frequencies, rotor trim performance, oscillatory structural blade loads, and transient rotor response to control inputs. Extensive comparisons are carried out with wind tunnel (WT) and flight test (FT) measurements found in the open literature as well as with nonreal-time comprehensive analysis methods. It is shown that the proposed approach exhibits good agreement with measured data regarding trim performance and transient rotor response characteristics. Accurate estimation of structural blade loads is demonstrated, in terms of both amplitude and phase, up to the third harmonic component o f oscillatory loading.It is shown that the developed model can be utilized for real-time simulation on a modern personal computer. The proposed methodology essentially con stitutes an enabling technology for the multidisciplinary design of rotorcraft, when a compromise between simulation fidelity and computational efficiency has to be sought for in the process of model development.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Real-Time Aero-elasticity Simulation of Open Rotors With Slender Blades for the Multidisciplinary Design of Rotorcraft

Goulos

Pachidis

2014

Journal of Engineering for Gas Turbines and Power

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“…Figures 16(a) and (b) present the calculated resonance charts for the Bo105 and the SA 330 helicopter rotor blades, respectively. Simulation results from Boeing-Vertol's computer code Y-71 (40) for the Bo105 hingeless blade with regards to flap/lag bending and torsional vibration natural frequencies at nominal rotorspeed, are annotated in Fig. 16(a).…”

Section: Comparison With Established Multi-body Analysis Methodsmentioning

confidence: 99%

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

Goulos

Pachidis

Pilidis

2014

Aeronaut. j. (1968)

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This paper presents a numerical formulation targeting the rapid estimation of natural vibration characteristics of helicopter rotor blades. The proposed method is based on application of Lagrange's equation of motion to the kinematics of blade flap/lag bending and torsion. Modal properties obtained from Bernoulli-Euler beam and classical torsional vibration theory, are utilised as assumed deformation functions in order to estimate the time variations of strain and kinetic energy for each degree of freedom. Integral expressions are derived, describing the generalised centrifugal force and torsional moment acting on the blade in terms of normal coordinates, for flap/ lag transverse displacement and torsional deformation. Closed form expressions are provided for the direct analysis of hingeless, freely-hinged and spring-hinged articulated rotor blades. Results are presented in terms of natural frequencies and mode shapes for two small-scale rotor blade models. Extensive comparisons are carried out with experimental measurements and nonlinear finite element analysis. Predictions of resonant frequencies are also presented for two full-scale rotor blade models and the results are compared with established multi-body dynamics analysis methods. It is shown that, the proposed approach exhibits excellent numerical behaviour with low computational cost and definitive convergence characteristics. The comparisons suggest very good and in some cases excellent accuracy levels, especially considering the method's simplicity, computational efficiency, and ease of implementation.

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“…This validates that the Sheng correction effectively predicts the capture of the leading edge vortex and its subsequent normal force variations in a low Mach number freestream. The modeling parameters for NACA23012 in the current work are listed in Table 1 and were derived by fitting the C81 table data from Reference [27]. Thanks to adequate public data, the current work used the Bo 105 helicopter as a base to implement the variable-speed rotor aerodynamic performance study; its rotor airfoil is NACA23012 and whose tail rotor airfoil is NACA0012.…”

Section: Modelingmentioning

confidence: 99%

Study on the Mechanism of the Variable-Speed Rotor Affecting Rotor Aerodynamic Performance

et al. 2018

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Abstract:The variable-speed rotor has proven to be a promising means to improve helicopter performance. Previous investigations on the aeromechanics of the variable-speed rotor are scarce. This work studies the mechanism of the variable-speed rotor affecting the rotor aerodynamic performance by means of dimensionless parameter analysis and reveals the various effect mechanisms under the various flight speeds and take-off weights. The current work shows that, during hover, the variable-speed rotor improves the rotor aerodynamic performance by reducing the blade dynamic pressure, while the non-uniform thrust distribution is attributed to the reduced rotor speed suppresses the performance improvement. In slow forward flight, the blade dynamic pressure reduction improves the rotor aerodynamic performance. In cruise and fast forward flight, both the blade dynamic pressure and advancing blade tip compression loss reductions improve the rotor aerodynamic performance. The study also shows that in forward flight, the rotor loading is smaller, and the effect of reducing the advancing blade tip compression loss through the variable-speed rotor is greater.

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Validation of Rotorcraft Flight Simulation Program through Correlation with Flight Data for Soft-in-Plane Hingeless Rotors

Cited by 19 publications

References 0 publications

Real-Time Aero-elasticity Simulation of Open Rotors With Slender Blades for the Multidisciplinary Design of Rotorcraft

Real-Time Aero-elasticity Simulation of Open Rotors With Slender Blades for the Multidisciplinary Design of Rotorcraft

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

Study on the Mechanism of the Variable-Speed Rotor Affecting Rotor Aerodynamic Performance

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