Reducing Trailing Edge Flap Deflection Requirements in Primary Control with a Movable Horizontal Tail

2011 ◽  
Vol 56 (3) ◽  
pp. 1-12 ◽  
Author(s):  
James E. Bluman ◽  
Farhan S. Gandhi
Keyword(s):  
Primary Control ◽  
Trailing Edge ◽  
Trailing Edge Flap ◽  
Flap Deflection

Effect of Trailing-Edge Flap Deflection on a Symmetric Airfoil Over a Wavy Ground

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
V. Tremblay-Dionne ◽  
T. Lee
Keyword(s):  
Experimental Investigation ◽  
Pitching Moment ◽  
Cyclic Variation ◽  
Trailing Edge ◽  
Opposite Trend ◽  
Aerodynamic Properties ◽  
Trailing Edge Flap ◽  
Flap Deflection ◽  
Naca 0015

The effect of trailing-edge flap (TEF) deflection on the aerodynamic properties and flowfield of a symmetric airfoil over a wavy ground was investigated experimentally. This Technical Brief is a continuation of Lee and Tremblay-Dionne (2018, “Experimental Investigation of the Aerodynamics and Flowfield of a NACA 0015 Airfoil Over a Wavy Ground,” ASME J. Fluids Eng., 140(7), p. 071202) in which an unflapped airfoil was employed. Regardless of the flap deflection, the cyclic variation in the sectional lift Cl and pitching moment Cm coefficients over the wavy ground always persists. The Cm also has an opposite trend to Cl. The flap deflection, however, produces an increased maximum and minimum Cl and Cm with a reduced fluctuation compared to their unflapped counterparts. The Cd increase outperforms the Cl increase, leading to a lowered Cl/Cd of the flapped airfoil.

On power and actuation requirement in swashplateless primary control of helicopters using trailing-edge flaps

2014 ◽  
Vol 118 (1203) ◽  
pp. 503-521
Author(s):  
F. Gandhi ◽  
C. Duling ◽  
F. Straub
Keyword(s):  
Aerodynamic Drag ◽  
Primary Control ◽  
Power Penalty ◽  
Trailing Edge ◽  
Level Flight ◽  
High Speeds ◽  
Steady Level ◽  
Trailing Edge Flaps ◽  
Trailing Edge Flap ◽  
Blade Tips

Abstract This paper examines three specific aspects pertaining to the trailing-edge flap (TEF) enabled swashplateless primary control of a helicopter. The study is based on a utility helicopter very similar to the UH-60A Blackhawk helicopter, with rotor torsion frequency reduced to 2·1/rev, and 20% chord TEFs extending from 70-90% span. The questions addressed in the paper are the power penalty due to aerodynamic drag associated with TEF control, the pitch-index required to limit the range of TEF deflections over variations in aircraft gross-weight and airspeed, and the influence of rotor RPM variation on swashplateless primary control. Results indicate that the power penalty associated with TEF enabled primary control at high speeds is in the range of 6-7%, due to increased drag on the advancing side in the region of the TEFs and at the blade tips. At low to moderate speeds the increase in power is 2-4% on average, more dependent on the pitch-index, and due to drag increase over most of the azimuth in the region of the TEFs. A variation in pitch-index from 16° for lower speeds and gross weights, to 20-22° for higher speeds and gross weights, would reduce the steady level flight TEF defection requirements to under ±3°, leaving sufficient control margin. Increase in rotor RPM does not increase directly increase thrust (as with a stiff-torsion rotor) but reduces the rotating torsion frequency, and together with the increased dynamic pressures increases the sensitivity to TEF control. At low to moderate speeds a 9% increase in RPM reduces the maximum TEF deflections required by about 1°, but is accompanied by a large increase in rotor power. Conversely, a 9% RPM reduction decreases rotor power required, but the TEF defections required increase by 1–1·5°.

Influence of Flap Deflection Angle on Wind Turbine Airfoil with Trailing Edge Flaps

2014 ◽  
Vol 977 ◽  
pp. 222-227
Author(s):  
Ya Lei Jia ◽  
Zhong He Han ◽  
Fu You Li ◽  
Ya Kai Bai ◽  
Ji Xuan Wang
Keyword(s):  
Wind Turbine ◽  
Deflection Angle ◽  
Aerodynamic Performance ◽  
Main Body ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Wind Turbine Airfoil ◽  
Trailing Edge Flap ◽  
Flap Deflection ◽  
Drag Ratio

To improve the ability of capturing the wind energy of wind turbine and shorten the design period is of great importance to designing wind turbine blade. The article established S809 airfoil model with trailing edge flaps, The gap of the frontal subject and trailing edge flap adopt uniform gap structure, this structure will reduce the influence of the gap on aerodynamic characteristics.Using the k-ω Two equation turbulence model , the article calculated aerodynamic performance of S809 with 10% chord length trailing edge flaps under different deflecting angles. Results show that gap between the main body and trailing edge flap has little effect on airfoil aerodynamic performance, however, the deflection Angle of Trailing edge flap have great affect on airfoil aerodynamic performance, when deflection Angle of trailing edge flap is 14 ° degrees ,the lift-to-drag ratio is the largest.

Trailing-edge flap flow control for dynamic stall

2011 ◽  
Vol 115 (1170) ◽  
pp. 493-503 ◽  
Author(s):  
R. B. Green ◽  
E. A. Gillies ◽  
Y. Wang
Keyword(s):  
Lower Surface ◽  
Rotor Blades ◽  
Surface Shape ◽  
Dynamic Stall ◽  
Limiting Factors ◽  
Trailing Edge ◽  
Oscillatory Dynamic ◽  
Trailing Edge Flap ◽  
Flap Deflection ◽  
Motion Profile

Abstract Results of a series of oscillatory dynamic stall tests of a rotor aerofoil fitted with a pulsed, trailing-edge flap are presented. Flap deflection amplitude, motion profile, duration and starting phase were investigated to assess the potential of the flap for mitigating the adverse effects of dynamic stall, which is one of the limiting factors for rotor blades on the retreating side of a helicopter rotor. The tests were a continuation of the investigations by Ref. 1 who used a computational fluid dynamics method on a symmetric NACA section, and our results broadly confirm their conclusions by experimental test, using a modern rotor section. The results presented in this paper also confirm the observations from experimental work by Refs 2 and 3, which were undertaken at lower Reynolds number and with a larger flap. In the present study, the flap mitigates the high negative pitching moment and negative pitch damping seen in dynamic stall by strong suction being generated over the aerofoil lower surface, and it is the modification to the lower surface shape by the flap that creates this effect. The dynamic stall vortex acts to enhance the lower surface suction, and careful flap phasing and flap motion profile shaping can make the control more effective.

Wind Tunnel Testing of a Swashplateless Rotor with Compact Brushless Motor Actuated Flaps for Primary Control

2020 ◽  
Vol 65 (1) ◽  
pp. 1-6
Author(s):  
Anand Saxena ◽  
Inderjit Chopra
Keyword(s):  
Wind Tunnel ◽  
Dc Motor ◽  
Brushless Dc Motor ◽  
Primary Control ◽  
Trailing Edge ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Trailing Edge Flaps ◽  
Weight Penalty ◽  
Trailing Edge Flap

A swashplateless rotor trim using brushless DC motor actuated trailing edge flaps was achieved in the Glenn L. Martin wind tunnel. A 6-ft-diameter, four-bladed articulated rotor with motor–flap system integrated into the NACA 0012 airfoil section was fabricated. A Maxon EC-10 brushless DC motor as an on-blade actuator and a lightweight mechanism were incorporated to actuate the trailing edge flap. The rotor torsion frequency was lowered to 2/rev using soft pitch links, allowing the blade pitch response to a trailing edge flap input. A closed-loop controller was employed to ensure trailing edge flap operation at desired amplitude with correct phase difference and in sync with the rotor azimuth. A trim methodology was implemented, and wind tunnel trim was achieved at 900 and 1200 RPM for a number of advance ratios. Results show that the brushless DC motors can provide sufficient primary control authority and have structural strength to withstand centrifugal loads, while fitting within airfoil profile and incurring minimal weight penalty.

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