scholarly journals Nonlinear Characteristics of Helicopter Rotor Blade Airfoils: An Analytical Evaluation

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Constantin Rotaru
Keyword(s):  
Aerodynamic Characteristics ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Apparent Mass ◽  
Nonlinear Characteristics ◽  
Helicopter Rotor Blades ◽  
Helicopter Rotor Blade ◽  
Attached Flow ◽  
Unsteady Effects ◽  
Physical Features

Some results are presented about the study of airloads of the helicopter rotor blades, the aerodynamic characteristics of airfoil sections, the physical features, and the techniques for modeling the unsteady effects found on airfoil operating under nominally attached flow conditions away from stall. The unsteady problem was approached on the basis of Theodorsen's theory, where the aerodynamic response (lift and pitching moment) is considered as a sum of noncirculatory and circulatory parts. The noncirculatory or apparent mass accounts for the pressure forces required to accelerate the fluid in the vicinity of the airfoil. The apparent mass contributions to the forces and pitching moments, which are proportional to the instantaneous motion, are included as part of the quasi-steady result.

Response of Helicopter Rotor Blades to Random Loads near Hover

1972 ◽  
Vol 23 (4) ◽  
pp. 276-284 ◽  
Author(s):  
C Lakshmikantham ◽  
C V Joga Rao
Keyword(s):  
Rotor Blades ◽  
Helicopter Rotor ◽  
Transverse Displacement ◽  
Random Input ◽  
Random Loading ◽  
Vertical Velocity Component ◽  
Random Loads ◽  
Helicopter Rotor Blades ◽  
Helicopter Rotor Blade ◽  
The Mean

SummaryThe response of a flexible helicopter rotor blade to random loading is investigated, the random input being the vertical velocity component. The model takes into account blade flexibility in bending as well as torsion, and also general root rigidity. The spectral density and the mean square value of the transverse displacement are computed for both hingeless and hinged rotor blades and the results are evaluated.

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 Chord Morphing for Helicopter Rotor Blades

2019 ◽  
Author(s):  
Johannes Riemenschneider ◽  
Christoph Balzarek ◽  
Berend G. van der Wall ◽  
Rohin Kumar Majeti
Keyword(s):  
Chord Length ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Forward Flight ◽  
Helicopter Rotors ◽  
Helicopter Rotor Blades ◽  
Helicopter Rotor Blade ◽  
Structural Concept ◽  
Final Design

Abstract Since helicopter rotors have different demands from different flight stats, the final design is always a compromise between flight stats such as hover and fast forward flight. Two of the design parameters are twist and chord length. This paper is giving some reasoning from rotor simulations on what twist and chord length should look like in order to increase performance in hover or forward flight. The result is, that the inboard chord length should be much larger for hover than for forward flight. This paper is presenting a structural concept, that can enable a helicopter rotor blade to change its chord length.

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.

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.

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