Variable cant angle winglets for improvement of aircraft flight performance
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Variable cant angle winglets for improvement of aircraft flight performance J. E. Guerrero
. M. Sanguineti . K. Wittkowski
Received: 30 July 2019 / Accepted: 20 August 2020 The Author(s) 2020
Abstract Traditional winglets are designed as fixed devices attached at the tips of the wings. The primary purpose of the winglets is to reduce the lift-induced drag, therefore improving aircraft performance and fuel efficiency. However, because winglets are fixed surfaces, they cannot be used to control lift-induced drag reductions or to obtain the largest lift-induced drag reductions at different flight conditions (take-off, climb, cruise, loitering, descent, approach, landing, and so on). In this work, we propose the use of variable cant angle winglets which could potentially allow aircraft to get the best all-around performance (in terms of lift-induced drag reduction), at different flight phases. By using computational fluid dynamics, we study the influence of the winglet cant angle and sweep angle on the performance of a benchmark wing at Mach numbers of 0.3 and 0.8395. The results obtained demonstrate that by adjusting the cant angle, the aerodynamic performance can be improved at different flight conditions. Keywords Winglets Variable cant angle Drag reduction CFD Lift-induced drag List of symbols a Speed of sound, measured in m/s J. E. Guerrero (&) M. Sanguineti K. Wittkowski DICCA, University of Genoa, via Montallegro 1, 16145 Genoa, Italy e-mail: [email protected]
AOA AOAeff AOAind CD CDmin CL CL0 CLmax CL =CD CP Ma C1 C2 D L P P1 Re Sref T T1 R us V V1 w
Angle-of-attack, measured in degrees ( ) Effective angle-of-attack, measured in degrees ( ) Induced angle-of-attack, measured in degrees ( ) Drag coefficient, nondimensional Minimum drag coefficient, nondimensional Lift coefficient, nondimensional Lift coefficient at zero angle-of-attack, nondimensional Maximum lift coefficient, nondimensional Lift-to-drag ratio, nondimensional Pressure coefficient, nondimensional Mach number, nondimensional Sutherland model coefficient, 1:458 106 kg=ðm s K0:5 Þ Sutherland model coefficient, 110.4 K Drag force, measured in N Lift force, measured in N Local pressure, measured in Pa Freestream pressure, measured in Pa Reynolds number, nondimensional Reference surface area, measured in m2 Local temperature, measured in K Freestream temperature, measured in K Air specific gas constant, 287.058 J/(kg K) pffiffiffiffiffiffiffiffiffiffi Shear velocity, sw =q, measured in m/s Local velocity, measured in m/s Freestream velocity, measured in m/s Downwash, measured in m/s
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Meccanica
yþ yw
Viscous wall units normal to the wall, yw us =m, nondimensional Normal distance from the wall to the first cell center, measured in m
Greek Symbols azl Angle-of-attack at zero lift, measured in degrees ( ) DCD Drag count, 1 DCD ¼ 10000 CD , nondimensional oCL =oAOA Slope of the lift curve, measured in 1= q Density, measured in kg=m3 c Air ratio of specific heat, 1.4, nondimensional l Dynam
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