Influence of Tip Shape, Chord, Blade Number, and Airfoil on Advanced Rotor Performance

McVeigh, Michael A.; McHugh, Francis J.

doi:10.4050/jahs.29.55

Cited by 18 publications

(11 citation statements)

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“…The use of composites makes practical to fabricate non-rectangular rotor blades, especially with advanced blade tips. Passive rotor blade shape design has seen great progress leading to improvements of helicopter rotor performance [2][3][4], and the aerodynamic parameters could be optimized to balance the requirement and obtain more performance improvement [5][6][7][8]. To further improve rotor performance is, however, a challenging topic.…”

Section: Introductionmentioning

confidence: 99%

Extendable chord for improved helicopter rotor performance

Han

Yang

Barakos

2018

Aerospace Science and Technology

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Extendable blade sections are investigated as a method for reducing rotor power and improving helicopter performance. A validated helicopter power prediction method, based on an elastic beam model is utilized. The static extendable chord can deliver a rather small power reduction in hover, and significant power savings at high speed flight, however, the cruise power is increased. In hover, the active chord is best deployed in the middle part of the blade, and just inboard of the tip at high speed flight. The increase in chord length can lead to power savings at high speed flight but the benefits decrease in other speeds. The 1/rev dynamically extendable chord can lead to an overall power reduction over the speed range of a helicopter. The best deployment location is at the blade tip, which is different from the statically extendable chord. It is best extended out in the retreating side, and retracted back in the advancing. The power reduction by the 1/rev dynamically extendable chord increases with the increase in the length of the chord extension and takeoff weight of the helicopter. Generally, a lower harmonic extendable chord can save more power than one actuated at higher harmonics. The dynamic chord can reduce more power than the corresponding static chord.

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Section: Introductionmentioning

confidence: 99%

Extendable chord for improved helicopter rotor performance

Han

Yang

Barakos

2018

Aerospace Science and Technology

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“…The calculation of tangential and perpendicular velocity is given as follows: The increment of lift on each blade element along the blade and around the azimuth is computed by using Equation 10.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The blade planform modification [9][10][11] is one of the commonly used methods to improve the forward speed of a helicopter. This modification is focused on the design at the tip of the blade whereby a poor design will contribute to serious implication on the rotor performance.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic prediction of helicopter rotor in forward flight using blade element theory

Yaakub¹,

Wahab²,

Abdullah³

et al. 2017

J. MECH. ENG. SCI.

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In this study, the helicopter blade in forward-flight condition was investigated. The blade element theory (BET) was used throughout this analysis to investigate the angle of attack variations at the blade cross sections, lift distribution along the blade and effects of increasing helicopter speed. Prouty's helicopter data was used to validate the analysis results. In this analysis, the helicopter blade was divided into 50 equally spaced elements and the azimuth ψ was set at 7.2° for each movement of the blade. The helicopter speed of 80 m/s was considered. The analysis revealed that the computation results were in good agreement with Prouty's diagram. Furthermore, it was also evident that in the case of a helicopter in forward-flight condition, the blade at retreating side was generally at low angle of attack and experienced low lift, in contrast to the blade at advancing side. The increment of the helicopter speed affected the lift distribution along the blade. The reverse flow area was widened two times from that given by the original Prouty's diagram. In addition, it was proven that each helicopter has its own speed limit called velocity never exceed (VNE). It was also shown that BET is important in conducting the analysis to modify the helicopter blade design for the aerodynamic characteristics' improvement as well as stability and general performance enhancement for the helicopter.

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“…Reynolds number r/R radial location t 1 , t 2 start and end time of one period U ∞ freestream velocity V forward velocity x independent variable, also airfoil geometry coordinate y response variable or matrix, also airfoil geometry coordinate α angle of attack α s forward shaft tilt θ 0 collective pitch θ 1 linear twist µ advance ratio ω frequency azimuthal angle angular velocity…”

mentioning

confidence: 99%

Technical Note: Aerodynamic Design of Helicopter Rotor Blade in Forward Flight Using Response Surface Methodology

Sun¹,

Kim²,

Lee³

et al. 2003

j am helicopter soc

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This paper describes an efficient and robust optimization method for helicopter rotor airfoil design in forward flight. Navier-Stokes analysis is employed to compute the dynamic response of an airfoil, which simulates the unsteady rotor flow-field in forward flight. The optimization system consists of two categories: Response Surface Method to construct the response surface model based on D-optimal 3-level factorial design, and Genetic Algorithm to obtain the optimum solution of a defined objective function including penalty terms of constraints. The influence of design variables and their interactions on the aerodynamic performance are examined through the optimization process.

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Influence of Tip Shape, Chord, Blade Number, and Airfoil on Advanced Rotor Performance

Cited by 18 publications

References 0 publications

Extendable chord for improved helicopter rotor performance

Extendable chord for improved helicopter rotor performance

Aerodynamic prediction of helicopter rotor in forward flight using blade element theory

Technical Note: Aerodynamic Design of Helicopter Rotor Blade in Forward Flight Using Response Surface Methodology

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