Modeling Helicopter Blade Sailing: Dynamic Formulation and Validation

2008 ◽  
Vol 75 (6) ◽  
Author(s):  
A. S. Wall ◽  
F. F. Afagh ◽  
R. G. Langlois ◽  
S. J. Zan
Keyword(s):  
Rotor Blade ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Dynamic Effects ◽  
Computationally Efficient ◽  
Helicopter Blade ◽  
Start Up ◽  
Dynamic Formulation ◽  
Element System ◽  
Blade Sailing

Rotor blade sailing, which is characterized by excessive deflection of rotor blades, can be experienced by shipboard helicopters during rotor start-up and shut-down. In an attempt to model the complete ship-helicopter-rotor system in a way that is geometrically representative and computationally efficient, the system was represented as a discrete-property rigid-body and flexible-element system capable of simulating many important dynamic effects that contribute to the motion of rotor blades. This paper describes the model in detail and discusses validation cases. While both dynamic effects and aerodynamic effects are believed to be important components of blade sailing, this paper focuses exclusively on the dynamics. The validation cases discussed herein suggest that the modeling approach presented offers excellent potential for efficiently modeling blade sailing and other blade motion phenomena.

scholarly journals ACTIVE TWIST OF MODEL ROTOR BLADES WITH D-SPAR DESIGN

Transport ◽  
2007 ◽  
Vol 22 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Andrejs Kovalovs ◽  
Evgeny Barkanov ◽  
Sergejs Gluhihs
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Rotor Blade ◽  
Element Model ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
3D Finite Element ◽  
3D Finite Element Model ◽  
Helicopter Rotor Blade ◽  
Active Twist

The design methodology based on the planning of experiments and response surface technique has been developed for an optimum placement of Macro Fiber Composite (MFC) actuators in the helicopter rotor blades. The baseline helicopter rotor blade consists of D‐spar made of UD GFRP, skin made of +450/‐450 GFRP, foam core, MFC actuators placement on the skin and balance weight. 3D finite element model of the rotor blade has been built by ANSYS, where the rotor blade skin and spar “moustaches” are modeled by the linear layered structural shell elements SHELL99, and the spar and foam ‐ by 3D 20‐node structural solid elements SOLID 186. The thermal analyses of 3D finite element model have been developed to investigate an active twist of the helicopter rotor blade. Strain analogy between piezoelectric strains and thermally induced strains is used to model piezoelectric effects. The optimisation results have been obtained for design solutions, connected with the application of active materials, and checked by the finite element calculations.

scholarly journals Fracture analysis of AA6061-graphite composite for the application of helicopter rotor blade

2021 ◽  
Vol 15 (58) ◽  
pp. 191-201
Author(s):  
Saleemsab Doddamani ◽  
Chao Wang Chao Wang ◽  
M. Sheik Mohamed Jinnah ◽  
Md. Arefin Kowser Md. Arefin Kowser
Keyword(s):  
Fracture Toughness ◽  
Rotor Blade ◽  
Compact Tension ◽  
Testing Procedure ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Graphite Material ◽  
Graphite Composite ◽  
Helicopter Rotor Blade

The main objective of the work is to study the fracture behavior of AA6061-graphite material using both experimental technique and finite element simulation by considering helicopter rotor blade as a case study. From the case study, it has been observed that the helicopter rotor blade, made of AA6061, has been failed at the threaded portion of the hole. Experimental fracture toughness is carried out using the compact tension specimens as per ASTM standard testing procedure. Modeling of compact tension specimens and the threaded portion of the bolt hole was utilized to analyze the fracture toughness using a simulation tool. From the results and the comparison, it is recommended to use AA6061-9wt% graphite material as a replacement of AA6061 in the application of main rotor blades of the helicopter.

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

2014 ◽  
Vol 118 (1206) ◽  
pp. 861-901 ◽  
Author(s):  
I. Goulos ◽  
V. Pachidis ◽  
P. Pilidis
Keyword(s):  
Rotor Blade ◽  
Computational Cost ◽  
Vibration Characteristics ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Mode Shapes ◽  
Small Scale ◽  
Transverse Displacement ◽  
Euler Beam ◽  
Rapid Estimation

Abstract 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.

Performance improvement of helicopter rotors through blade redesigning

2019 ◽  
Vol 91 (5) ◽  
pp. 747-755
Author(s):  
Wienczyslaw Stalewski ◽  
Wieslaw Zalewski
Keyword(s):  
Performance Improvement ◽  
Rotor Blade ◽  
Parametric Design ◽  
Aerodynamic Characteristics ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Content Type ◽  
Simplified Approach ◽  
Helicopter Rotor Blades ◽  
Blade Shape

Purpose The purpose of this paper is to determine dependencies between a rotor-blade shape and a rotor performance as well as to search for optimal shapes of blades dedicated for helicopter main and tail rotors. Design/methodology/approach The research is conducted based on computational methodology, using the parametric-design approach. The developed parametric model takes into account several typical blade-shape parameters. The rotor aerodynamic characteristics are evaluated using the unsteady Reynolds-averaged Navier–Stokes solver. Flow effects caused by rotating blades are modelled based on both simplified approach and truly 3D simulations. Findings The computational studies have shown that the helicopter-rotor performance may be significantly improved even through relatively simple aerodynamic redesigning of its blades. The research results confirm high potential of the developed methodology of rotor-blade optimisation. Developed families of helicopter-rotor-blade airfoils are competitive compared to the best airfoils cited in literature. The finally designed rotors, compared to the baselines, for the same driving power, are characterised by 5 and 32% higher thrust, in case of main and tail rotor, respectively. Practical implications The developed and implemented methodology of parametric design and optimisation of helicopter-rotor blades may be used in future studies on performance improvement of rotorcraft rotors. Some of presented results concern the redesigning of main and tail rotors of existing helicopters. These results may be used directly in modernisation processes of these helicopters. Originality/value The presented study is original in relation to the developed methodology of optimisation of helicopter-rotor blades, families of modern helicopter airfoils and innovative solutions in rotor-blade-design area.

scholarly journals Helicopter Rotor Sailing by Non-Smooth Dynamics Co-Simulation

2014 ◽  
Vol 61 (2) ◽  
pp. 253-268 ◽  
Author(s):  
Matteo Fancello ◽  
Marco Morandini ◽  
Pierangelo Masarati
Keyword(s):  
Differential Algebraic Equations ◽  
General Purpose ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Nonsmooth Dynamics ◽  
Algebraic Equations ◽  
Helicopter Rotor Blades ◽  
Reaction Forces ◽  
Blade Sailing ◽  
Smooth Dynamics

Abstract This paper presents the application of a co-simulation approach for the simulation of frictional contact in general-purpose multibody dynamics to a rotorcraft dynamics problem. The proposed approach is based on the co-simulation of a main problem, which is described and solved as a set of differential algebraic equations, with a subproblem that is characterized by nonsmooth dynamics events and solved using a timestepping technique. The implementation and validation of the formulation is presented. The method is applied to the analysis of the droop and anti-flap contacts of helicopter rotor blades. Simulations focusing on the problem of blade sailing are conducted to understand the behavior and assess the validity of the method. For this purpose, the results obtained using a contact model based on Hertzian reaction forces at the interface are compared with those of the proposed approach.

Unsteady Forces Acting on the Rotor Blades and Shaft in the Control Stage for Different Steam Admission Variants

2010 ◽  
Author(s):  
Romuald Rza˛dkowski ◽  
Marek Solin´ski
Keyword(s):  
Rotor Blade ◽  
Gas Flow ◽  
Low Frequency ◽  
Ideal Gas ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Unsteady Forces ◽  
Control Stage ◽  
Start Up ◽  
Steam Admission

This paper concerns the unsteady high- and low-frequency excitation forces acting on the rotor blades and shaft in the control stage of a 200 MW steam turbine. An ideal gas flow through mutually moving stator and rotor blades was described in the form of unsteady Euler conservation equations, which were integrated using the Godunov-Kolgan explicit monotonous finite-volume difference scheme and a hybrid H-H grid. The effect of rotor blade mistuning on the unsteady forces acting on both the blades and the shaft was examined. Four different control stage steam admission variants were analysed. The actual levels of the stationary components of particular forces were determined by changes in the operating conditions of individual nozzle segments. Different mistuning variants generated different distributions of unsteady rotor blade force harmonics. The presented results show that the first harmonic does not always dominate the spectrum. When considering forces acting on the rotor blades and shaft, there exists an optimal procedure of turbine start-up.

Circulation Control Span-Wise Blowing Location Optimization for a Helicopter Rotor Blade

2010 ◽  
Author(s):  
Alan M. Didion ◽  
Jonathan Kweder ◽  
Mary Ann Clarke ◽  
James E. Smith
Keyword(s):  
Stress Reduction ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Base Line ◽  
Control Technology ◽  
Circulation Control ◽  
High Lift ◽  
Location Optimization ◽  
Helicopter Rotor Blades ◽  
Length Reduction

Circulation control technology has proven itself useful in the area of short take-off and landing (STOL) fixed wing aircraft by decreasing landing and takeoff distances, increasing maneuverability and lift at lower speeds. The application of circulation control technology to vertical take-off and landing (VTOL) rotorcraft could also prove quite beneficial. Successful adaptation to helicopter rotor blades is currently believed to yield benefits such as increased lift, increased payload capacity, increased maneuverability, reduction in rotor diameter and a reduction in noise. Above all, the addition of circulation control to rotorcraft as controlled by an on-board computer could provide the helicopter with pitch control as well as compensate for asymmetrical lift profiles from forward flight without need for a swashplate. There are an infinite number of blowing slot configurations, each with separate benefits and drawbacks. This study has identified three specific types of these configurations. The high lift configuration would be beneficial in instances where such power is needed for crew and cargo, little stress reduction is offered over the base line configuration. The stress reduction configuration on the other hand, however, offers little extra lift but much in the way of increased rotor lifespan and shorter rotor length. Finally, the middle balanced configuration offers a middle ground between the two extremes. With this configuration, the helicopter benefits in all categories of lift, stress reduction and blade length reduction.

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