A framework for CFD analysis of helicopter rotors in hover and forward flight

Steijl, R.; Barakos, George N.; Badcock, K. J.

doi:10.1002/fld.1086

Cited by 180 publications

(160 citation statements)

References 20 publications

(46 reference statements)

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“…The flow was considered as fully turbulent and compressible. The HMB code (developed at the University of Liverpool, UK) is used (Nik and Barakos, 2012), (Steijl et al, 2006). For hover, a steady-state formulation is employed to reduce the overall computational effort.…”

Section: Problem Formulation and Research Methodsmentioning

confidence: 99%

Aerodynamic and acoustic analysis of helicopter main rotor blade tips in hover

Garipova

Batrakov

Kusyumov

et al. 2016

HFF

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Purpose -The design of main rotor blade tips is of interest to helicopter manufacturers since the tip details affect the aerodynamic performance and acoustics of the rotor. The aim of this paper is the numerical simulation the flow around hovering helicopter blades with different tip designs.Design/methodology/approach -In this paper, CFD is used to simulate the flow around hovering helicopter blades with different tip designs. For each type of blade tip a parametric study on the shape is also conducted. For comparison, calculations were performed at the same rotor thrust. The collective pitch of the blades and the coning angle of the rotor were determined by an iterative trimming process. The aeroacoustic characteristics of the rotors were obtained using the Ffowcs Williams -Hawkings equation.Findings -Analysis of the distributed blade loads shows that the tip geometry has a significant influence on aerodynamics and aeroacoustics especially for stations where blade loading is high.Originality/value -The results are useful for design new blades with high performance and low acoustic emission. INTRODUCTIONResearch into helicopter blade tips is important for helicopter manufacturers. Past and recent papers demonstrate the constant interest of researchers in this problem. The results show potential to increase the aerodynamic efficiency of the rotor and to reduce its acoustics (aero-acoustic noise). Brocklehurst and Barakos (2012) present a recent review of works dedicated to different aspects of blade tip design. In (Yen, 1994) swept-tapered blade tips were compared with swept, tapered and rectangular versions. In high speed flight the swept-tapered tip reduced the pitch link loads and the blade vibration. Trailing vortex measurements in hover have also been reported in (Martin and Leishman, 2002) for various tip shapes including rectangular, tapered, swept, and a sub-wing tips. One of the primary differences noted was the dependence of wake geometry on the tip shape. The tapered tip reduced the initial swirl velocity, increased the radial convection and decreased the axial convection. The quiet Helicopter demonstrator is discussed in (Allongue et al., 1999). The blade tip shape has a parabolic leading edge and is highly tapered, and therefore has low volume. This tip has some benefits in hover efficiency and noise performance but use on heavier, faster helicopters may be limited by advancing side compressibility effects and retreating side blade stall. According to (Brocklehurst and Barakos, 2012) three families of blade tips (Figure 1) have so far received attention: parabolic, swept and BERP tips. Further improvements and a reduction of the blade noise can be achieved by modifying the rest of the blade plan form. This was attempted with the "ERATO" (Beaumier and Delrieux, 2003) and "Blue Edge" (Rauch et al., 2011) designs. On the ERATO rotor, the blade curves forward and the main sweep-back starts inboard. The aim of this blade design is to reduce blade-vortex interaction (BVI) noise. Anhedral has been...

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Section: Problem Formulation and Research Methodsmentioning

confidence: 99%

Aerodynamic and acoustic analysis of helicopter main rotor blade tips in hover

Garipova

Batrakov

Kusyumov

et al. 2016

HFF

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“…All CFD calculations shown here were performed using the Helicopter Multi-Block Method (HMB2) taking advantage of its ability to perform steady-state periodic or fully unsteady computations [25] using the RANS and URANS approach or even SAS [26] and DES [27]. For this work, fine multi-block grids were used with the sliding plane method [28]. The grids had approximately 12 million cells per blade for the isolated cases.…”

Section: Cfd Modelmentioning

confidence: 99%

“…Examples of work with HMB2 can be found in references [28, 32, and 33]. Several rotor trimming methods are available in HMB2 along with a blade-actuation algorithm that allows for the near-blade grid quality to be maintained on deforming meshes [28].…”

Section: Cfd Modelmentioning

confidence: 99%

Helicopter performance improvement by variable rotor speed and variable blade twist

Han

Pastrikakis

Barakos

2016

Aerospace Science and Technology

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Variable rotor speed and variable blade twist are combined to reduce rotor power and improve helicopter performance.Two modeling methods are respectively utilized. One is based on an empirical aerodynamic model and the other is based on CFD (computational fluid dynamics). The flight data of the UH-60A helicopter is used to validate the methods. The predictions of the rotor power by the empirical method are in good agreement with the test data and the CFD method, which verifies the application of present methods in analyzing helicopter performance. The analyses indicate that significant rotor power reduction can be achieved by decreasing rotor speed. It is not appropriate to decrease the rotor speed too much in high forward flight. More power reduction can be attained by varying rotor speed than by variable blade twist.The individual variation of rotor speed or blade twist can reduce the rotor power by 17.8% or 10.4%, at a forward speed 250 km/h and weight coefficient of 0.0065. A combination of rotor speed reduction and blade twist can save 20.9%. The maximum power reduction increases with forward speed and then decreases. The optimal performance improvement occurs at the medium to high forward speed. With increasing takeoff weight, the benefit in power saving decreases. Variable blade twist has the potential in reducing blade loads introduced by variable rotor speed.

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“…The first step in the development of new optimization approaches for the airframe was the validation of the CFD software in use in Leonardo Helicopters: Fluent™ (3), AeroFOAM (4) and HMB (2). Four airfoils were selected for this test, representative of tilt rotor wing airfoils.…”

Section: A Work Packagementioning

confidence: 99%

The Collaborative Development of New CFD Methods Adapted for Tilt Rotor Aircraft in the HiPerTilt Project

Dehaeze

Allen

Barakos

2017

35th AIAA Applied Aerodynamics Conference

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Following new requirements for CFD tools regarding tilt rotor aircraft, Leonardo Helicopters, partnering with the Universities of Bristol and Glasgow and Innovate UK, launched the HiPerTilt project, aimed at designing and validating new methods adapted to new aircraft. It was also required that these methods should be compatible with conventional helicopters. The project, focusing on both the airframe and the rotor aerodynamics, was split in five work packages, and the main achievements are described in this paper. The new methods have proven efficient and adapted for use in industrial processes. The strong cooperation between the partners, associated with the expertise of the partnering Universities, was one of the key factors contributing to the success of the project.

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A framework for CFD analysis of helicopter rotors in hover and forward flight

Cited by 180 publications

References 20 publications

Aerodynamic and acoustic analysis of helicopter main rotor blade tips in hover

Aerodynamic and acoustic analysis of helicopter main rotor blade tips in hover

Helicopter performance improvement by variable rotor speed and variable blade twist

The Collaborative Development of New CFD Methods Adapted for Tilt Rotor Aircraft in the HiPerTilt Project

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