Numerical Research on the Unsteady Evolution Characteristics of Blade Tip Vortex for Helicopter Rotor in Forward Flight

The wandering motion of tip vortices trailed from a hovering helicopter rotor is described. This aperiodicity is known to cause errors in the determination of vortex properties that are crucial inputs for refined aerodynamic analyses of helicopter rotors. Measurements of blade tip vortices up to 260 deg vortex age using stereo particle-image velocimetry (PIV) indicate that this aperiodicity is anisotropic. We describe an analytical model that captures this anisotropic behavior. The analysis approximates the helical wake as a series of vortex rings that are allowed to interact with each other. The vorticity in the rings is a function of the blade loading. Vortex core growth is modeled by accounting for vortex filament strain and by using an empirical model for viscous diffusion. The sensitivity of the analysis to the choice of initial vortex core radius, viscosity parameter, time step, and number of rings shed is explored. Analytical predictions of the orientation of anisotropy correlated with experimental measurements within 10%. The analysis can be used as a computationally inexpensive method to generate probability distribution functions for vortex core positions that can then be used to correct for aperiodicity in measurements.

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Helicopter rotor blade aeroelasticity in forward flight with an implicit structural formulation

10.2514/6.1991-1219 ◽

1991 ◽

Author(s):

ROBERTO CELI

Keyword(s):

Rotor Blade ◽

Helicopter Rotor ◽

Forward Flight ◽

Helicopter Rotor Blade

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Some improvements of hybrid trim method for a helicopter rotor in forward flight

Aerospace Science and Technology ◽

10.1016/j.ast.2021.106709 ◽

2021 ◽

Vol 113 ◽

pp. 106709

Author(s):

Weili Lyu ◽

Shiyuan Wang ◽

Aiming Yang

Keyword(s):

Helicopter Rotor ◽

Forward Flight

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Dynamic Mesh Analyses of Helicopter Rotor–Fuselage Flow Interaction in Forward Flight

Journal of Aerospace Engineering ◽

10.1061/(asce)as.1943-5525.0000641 ◽

2016 ◽

Vol 29 (6) ◽

pp. 04016050 ◽

Cited By ~ 1

Author(s):

Mustafa Berkay Açıkgöz ◽

Alim Rüstem Aslan

Keyword(s):

Dynamic Mesh ◽

Helicopter Rotor ◽

Forward Flight ◽

Flow Interaction

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Aerodynamic design optimization of helicopter rotor blades including airfoil shape for forward flight

Aerospace Science and Technology ◽

10.1016/j.ast.2014.10.020 ◽

2015 ◽

Vol 42 ◽

pp. 106-117 ◽

Cited By ~ 18

Author(s):

N.A. Vu ◽

J.W. Lee

Keyword(s):

Design Optimization ◽

Rotor Blades ◽

Helicopter Rotor ◽

Aerodynamic Design ◽

Forward Flight ◽

Aerodynamic Design Optimization ◽

Helicopter Rotor Blades

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

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.11.2.2017.12.0246 ◽

2017 ◽

Vol 11 (2) ◽

pp. 2711-2722

Author(s):

M.F. Yaakub ◽

◽

A.A. Wahab ◽

A. Abdullah ◽

N.A.R. Nik Mohd ◽

...

Keyword(s):

Helicopter Rotor ◽

Forward Flight ◽

Blade Element Theory ◽

Element Theory ◽

Blade Element

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Investigation of the Blade Tip Clearance Effects on Performance and Stability of a Mixed-Flow Pump: High Speed Camera Recordings of the Flow Structures, Local Measurements and Numerical Simulation

Volume 4A: Dynamics, Vibration, and Control ◽

10.1115/imece2015-50398 ◽

2015 ◽

Author(s):

Alberto Serena ◽

Lars E. Bakken

Keyword(s):

High Speed ◽

Detailed Comparison ◽

Performance Comparison ◽

Tip Clearance ◽

Tip Vortex ◽

High Speed Camera ◽

Tip Leakage Flow ◽

Quality Video ◽

Local Measurements ◽

Blade Tip

The tip leakage flow affects turbomachines performance generating losses and reducing the effective blading; in addition, unsteady phenomena arise, negatively influencing the machine stability. In this paper, an overview of the existing models is presented. Local measurements of the pressure pulsations, visual flow observations and high quality video recordings from a high speed camera are performed in a novel pump laboratory, which provides the desired visualization of the rotating channels, and allows to study the fluctuating and intermittent nature of this phenomenon, and detect any asymmetry among the channels. A detailed comparison of the vortex tip structure for various tip clearances and with a whole set of numerical simulations finally completes the analysis. The three main focus areas are: tip vortex location, structure and evolution, performance comparison between shrouded and open impeller, at different tip clearance sizes, and study of the rotating instabilities.

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