Wing Flutter Suppression under the Influence of Fuel Sloshing in External Tank

2021 ◽  
Vol 34 (5) ◽  
pp. 04021062
Author(s):  
Jiangtao Xu ◽  
Quanxi Gao ◽  
Hongqing Lv ◽  
Ya Yang ◽  
Bangsheng Fu
Keyword(s):  
Flutter Suppression ◽  
Wing Flutter

Higher Harmonic Control: A Historical Perspective

2021 ◽  
Author(s):  
Charles E. Hammond
Keyword(s):  
Wind Tunnel ◽  
Ride Quality ◽  
Flight Tests ◽  
Flutter Suppression ◽  
Harmonic Control ◽  
Wing Flutter ◽  
Higher Harmonic Control ◽  
Higher Harmonic ◽  
Langley Research Center ◽  
Helicopter Vibration

Higher harmonic control (HHC) is an approach for achieving reduced helicopter vibration by controlling the vibratory rotor airloads in such a way that the fuselage excitation is minimized. This paper is a historical look at how a program aimed at helicopter vibration reduction started as an outgrowth of fixed wing flutter suppression at NASA Langley Research Center, proved the HHC concept on aeroelastically scaled wind tunnel models and went on to demonstrate viability in full-scale flight testing on the OH-6A helicopter in 1982. Following the OH-6A flight tests, the helicopter research community was stimulated to prove the effectiveness of HHC on different configurations through analysis, wind tunnel tests, and flight tests. All of these investigations have shown HHC to be effective in reducing vibration to levels not attainable with conventional vibration control methods and without any detrimental side effects. HHC development has progressed to the point that the technology provides one more option to address the ever-present vibration problem in helicopters. The literature demonstrates that helicopter ride quality equivalent to that of fixed wing aircraft is attainable with application of HHC.

Robust Wing Flutter Suppression Considering Aerodynamic Uncertainty

2004 ◽  
Vol 41 (2) ◽  
pp. 331-334 ◽  
Author(s):  
Dan Borglund ◽  
Ulrik Nilsson
Keyword(s):  
Flutter Suppression ◽  
Wing Flutter

Eccentric-wing flutter stabilizer – Simplified analysis and main findings

2019 ◽  
Author(s):  
Uwe Starossek
Keyword(s):  
Wind Tunnel ◽  
Cost Efficiency ◽  
Bridge Deck ◽  
Simplified Approach ◽  
Flutter Suppression ◽  
Wing Flutter ◽  
Simplified Analysis ◽  
Lateral Offset ◽  
Tacoma Narrows Bridge ◽  
Moving Parts

<p>A device aiming at preventing bridge flutter is studied. It consists of fixed wings positioned with a large lateral offset along the edges of the bridge deck. The wings are attached to the bridge deck by means of lateral support structures. Flutter analyses for various kinds of bridges and wind-tunnel tests confirm the flutter-suppression effectiveness of the wings. They constitute a passive damping device without moving parts. This is an advantage over devices with moving parts, which meet resistance due to reliability and maintenance concerns. The main findings to date concerning analysis, flutter-suppression effectiveness, and cost-efficiency of the eccentric-wing flutter stabilizer are summarized. In addition, a simplified approach for the analysis of torsional flutter of a bridge equipped with this device is presented and applied to the first Tacoma Narrows Bridge. It is found that with relatively small effort the flutter stability of that bridge could have been substantially improved.</p>

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