Gust Alleviation of a Large Aircraft with a Passive Twist Wingtip
Abstract
:1. Introduction
2. Design Requirements and Analysis Methods
2.1. Design Requirements and Procedure
2.2. Aeroelastic Analysis
2.3. Gust Model and Load
3. Aircraft Design Example and Results
3.1. Aircraft Data and Aerodynamic Load
Wing Span (m) | Aspect Ratio | Leading Edge Sweep Angle (deg) | Fuselage Length (m) | MTOM (Maximum Take-Off Mass) (kg) | OEM (Operation Empty Mass) (kg) | Cruise Altitude (feet) |
---|---|---|---|---|---|---|
38.3 | 12 | 5.0 | 44.5 | 87,663.0 | 46,500.0 | 35,000 |
3.2. Structural Layout and Initial Design
E1 (GPa) | E2 (GPa) | G12 (GPa) | v12 | Xt (MPa) | Xc (MPa) | Yt (MPa) | Yc (MPa) | S (MPa) | ρ (kg/m3) |
---|---|---|---|---|---|---|---|---|---|
176 | 15 | 5.6 | 0.27 | 3520 | 1880 | 42.7 | 127 | 105 | 1586 |
3.3. Structural FE Model and Stress Analysis
3.4. Aeroelastic and Gust Response Analysis
Mode (Hz) | 1st Bending | 2nd Bending | Bending/Torsion Coupled | 1st Torsion | 3rd Bending |
---|---|---|---|---|---|
MTOM | 3.5 | 9.5 | 11.1 | 17.0 | 20.3 |
OEM | 4.0 | 12.4 | 18.6 | 17.4 | 31.2 |
Gust Gradient Distance H (m) | 9.0 | 25 | 12.5 = 48.5 | 107.0 |
---|---|---|---|---|
Design gust velocity Uds (m/s) | 6.63 | 7.86 | 8.77 | 10.01 |
Gust frequency (Hz) | 9.72 | 3.50 | 1.80 | 0.80 |
Altitude | Airspeed | Case | Gust Response (mm) | |||
---|---|---|---|---|---|---|
H = 9 m | H = 25 m | H = 48.5 m | H = 107 m | |||
Sea level | VB | MTOM | 466 | 677 | 968 | 1,179 |
OEM | 484 | 647 | 867 | 1,037 | ||
VC | MTOM | 474 | 960 | 1,261 | 1,586 | |
OEM | 474 | 959 | 1,261 | 1,587 | ||
Cruise altitude | VC | MTOM | 216 | 465 | 614 | 776 |
OEM | 217 | 464 | 614 | 776 |
4. The PTWT Design and Gust Response
4.1. The PTWT Key Parameters and Influence on Gust Response
Altitude | Airspeed | H = 9 m | H = 25 m | H = 48.5 m | H = 107 m |
---|---|---|---|---|---|
Sea level | VB | −7.7% | −9.7% | −23.4% | −22.0% |
VC | −5.1% | −12.6% | −21.2% | −9.8% | |
Cruise altitude | VC | −6.5% | −10.5% | −18.4% | −24.3% |
4.2. Gust Response of the Whole Aircraft
Case | Normal Acceleration at CG | Bending Moment | Wing Deflection |
---|---|---|---|
MTOM | −2.4% | −10.6% | −21.2% |
OEM | −3.2% | −14.4% | −20.6% |
4.3. The PTWT Influence on the Flight Manoeuvre Performance
Parameter | MTOM | OEM |
---|---|---|
Max normal acceleration | −2.7% | −2.6% |
Vertical speed after 4 s | −1.7% | −0.6% |
Heave after 4 s | −2.9% | −1.6% |
Parameter | MTOM | OEM |
---|---|---|
Maximum roll acceleration | −13.5% | −13.6% |
Roll rate after 4 s | −11.6% | −11.8% |
Roll angle after 4 s | −10.6% | −10.8% |
5. Conclusions
Notation
a1 | Lift curve slope of the wing |
c | Wing mean chord |
[Dhh] | Generalized damping matrix |
E1/E2 | Ply modulus in fiber/off-fiber direction |
Fg | Flight profile alleviation factor |
G12 | Shear modulus of the ply |
H | Gust gradient distance |
k | Reduced frequency |
K | Spring stiffness of the PTWT |
[Khh] | Generalized stiffness matrix |
L | Aerodynamic lift force |
{LG} | Gust induced aerodynamic force vector |
{Lhh} | Unsteady aerodynamic force vector |
[Mhh] | Generalized mass matrix |
{qh} | Generalized coordinate vector |
{QG} | Generalized aerodynamic force due to gust |
[Qhhi] | Generalized unsteady aerodynamic matric (imaginary part) |
[QhhR] | Generalized unsteady aerodynamic matric (real part) |
p | Static pressure |
s | Reference area of the wing |
S | Shear strength of ply |
U | Gust velocity |
Uds | Design gust velocity |
Uref | Reference gust velocity |
V | Airspeed |
VB | Design speed for maximum gust velocity |
VC | Cruise airspeed |
VD | Dive airspeed |
Vf | Flutter airspeed |
Xt/Xc | Tension/compression strength of ply in fiber direction |
Yt/Yc | Tension/compression strength of ply in off-fiber direction |
Zmo | Maximum operating altitude |
λ | Decay constant |
µ | Mass parameter |
ρ | Air density |
ν12 | Poisson’s ration of ply |
ω | Gust frequency |
[Φ] | Modal matrix of the structure in special coordinates |
Abbreviations
AoA | Angle of attack |
CFD | Computational Fluid Dynamics |
CG | Center of gravity |
FE | Finite element |
FI | Failure Index |
MLM | Maximum landing mass |
MTOM | Maximum take-off mass |
MZFM | Maximum zero fuel mass |
OEM | Operating empty mass |
PTWP | Passive twist wing tip (device) |
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Guo, S.; De Los Monteros, J.E.; Liu, Y. Gust Alleviation of a Large Aircraft with a Passive Twist Wingtip. Aerospace 2015, 2, 135-154. https://doi.org/10.3390/aerospace2020135
Guo S, De Los Monteros JE, Liu Y. Gust Alleviation of a Large Aircraft with a Passive Twist Wingtip. Aerospace. 2015; 2(2):135-154. https://doi.org/10.3390/aerospace2020135
Chicago/Turabian StyleGuo, Shijun, Jaime Espinosa De Los Monteros, and Ying Liu. 2015. "Gust Alleviation of a Large Aircraft with a Passive Twist Wingtip" Aerospace 2, no. 2: 135-154. https://doi.org/10.3390/aerospace2020135