scholarly journals Experimental investigation of a helicopter rotor with Gurney flaps

2017 ◽  
Vol 121 (1236) ◽  
pp. 191-212 ◽  
Author(s):  
G. Gibertini ◽  
A. Zanotti ◽  
G. Droandi ◽  
F. Auteri ◽  
G. Crosta
Keyword(s):  
Particle Image ◽  
Control Volume ◽  
Helicopter Rotor ◽  
Aerodynamic Loads ◽  
Gurney Flaps ◽  
Gurney Flap ◽  
Image Velocimetry ◽  
Blade Section ◽  
Control Volume Approach ◽  
Rotor Model

ABSTRACTThe present work describes an experimental activity carried out to investigate the performance of Gurney flaps on a helicopter rotor model in hovering. The four blades of the articulated rotor model were equipped with Gurney flaps positioned at 95% of the aerofoil chord, spanning 14% of the rotor radius. The global aerodynamic loads and torque were measured for three Gurney flap configurations characterised by different heights. The global measurements showed an apparent benefit produced by Gurney flaps in terms of rotor performance with respect to the clean blade configuration. Particle image velocimetry surveys were also performed on the blade section at 65% of the rotor radius with and without the Gurney flaps. The local velocity data was used to complete the characterisation of the blade aerodynamic performance through the evaluation of the sectional aerodynamic loads using the the control volume approach.

Particle Image Velocimetry Based Measurement of Entropy Production With Free Convection Heat Transfer

2005 ◽  
Vol 127 (6) ◽  
pp. 614-623 ◽  
Author(s):  
O. B. Adeyinka ◽  
G. F. Naterer
Keyword(s):  
Particle Image Velocimetry ◽  
Free Convection ◽  
Entropy Production ◽  
Particle Image ◽  
Control Volume ◽  
Temperature Fields ◽  
Element Formulation ◽  
Measured Velocity ◽  
Numerical Predictions ◽  
Image Velocimetry

Local entropy production rates are determined from a numerical and experimental study of natural convection in an enclosure. Numerical predictions are obtained from a control-volume-based finite element formulation of the conservation equations and the Second Law. The experimental procedure combines methods of particle image velocimetry and planar laser induced fluorescence for measured velocity and temperature fields in the enclosure. An entropy based conversion algorithm in the measurement procedure is developed and compared with numerical predictions of free convection in the cavity. The predicted and measured results show close agreement. A measurement uncertainty analysis suggests that the algorithm postprocesses velocities (accurate within ±0.5%) to give entropy production data, which is accurate within ±8.77% near the wall. Results are reported for free convection of air and water in a square cavity at various Rayleigh numbers. The results provide measured data for tracking spatial variations of friction irreversibility and local exergy losses.

Aerodynamic load characterisation of a low speed aerofoil using particle image velocimetry

2008 ◽  
Vol 112 (1130) ◽  
pp. 197-205 ◽  
Author(s):  
B. W. van Oudheusden ◽  
E. W. F. Casimiri ◽  
F. Scarano
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Control Volume ◽  
Flow Simulation ◽  
Momentum Equation ◽  
Aerodynamic Load ◽  
Surface Pressure Distribution ◽  
Velocity Statistics ◽  
Image Velocimetry ◽  
Standard Pressure

AbstractParticle image velocimetry (PIV) measurements of the flow around a wing section are employed as a basis for non-intrusive aerodynamic mean loads characterisation, providing sectional lift, drag and pitching moment. The technique relies upon the application of control-volume approaches in combination with the deduction of the pressure from the PIV experimental data through application of the momentum equation. The treatment can also be applied when the flow is unsteady; in that case time-mean loads are obtained from velocity statistics, through the use of Reynolds-averaged formulation of the governing equations. The procedure was applied in the experimental investigation of a NACA 642A015 aerofoil, in which the PIV approach is validated against standard pressure-based methods (surface pressure distribution and wake rake). The chord Reynolds number considered in the investigation ranges between 1 – 7 × 105. In addition, the consistency and potential performance of the method was assessed by means of synthetic velocity field data obtained from a numerical flow simulation.

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