2018/3/11 圆上活大学 Drag Terminology 国上清大学 Drag- Profile Drag +Induced Drag!+Wave Drag 恤rg然am SECTION B-II AERODYNAMIC FORCES-DRAG oorornenin ong zero lift drag Drag Terminology-中文版 国上活大坐 Total Drag Decomposition 圆上洋廷大整 Fratve dag 日过 Zero-lift,or parasite drag- 即力二 型用 +诱导阻力 +激波阻力 农 1 Induced drag,or drag due to lift- Cni=kC2=CLπeA Drag due to compressibility,or wave drag for transonic flows, therefore Cpo=Cpoform +Cpofriction+Cpi 升致阳力 nbin Song零升阴力 oerandenn ong 22 More Details on Induced Drag 国上洋大坐 Parasite Drag 国上洋大学 with induced Cp.i-Cp.Cp. CoC Second approach uses"Component Buildup Method" CccCr Shanghal Jao Tong Universty-Dr.Wenbin Soog erslty-Dr.Wrenbin Song 42018/3/11 4 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics AERODYNAMIC FORCES - DRAG SECTION B-II © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Drag Terminology Ref: Research report 2011:02, aircraft drag reduction: an overview [1360] © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Drag Terminology – 中文版 © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Total Drag Decomposition • Zero-lift, or parasite drag – – form drag, also known as viscous pressure drag – Friction drag, due to shearing stresses at the surface • Induced drag, or drag due to lift – • Drag due to compressibility, or wave drag for transonic flows, therefore •22 CD,0 = CD,0,form + CD,0,friction CD,i = kCL 2 =CL 2 /πeA CD,0 = CD,0,form +CD,0,friction + CD,i © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics More Details on Induced Drag • Induced drag includes more than just the inviscid drag associated with induced velocities from the wake • It is generally stated that minimum induced drag is achieved for elliptical spanwise loading from aerodynamic perspective CD, i =CD, vortex+CD, lift-dependent viscous © Shanghai Jiao Tong University – Dr. Wenbin Song School of Aeronautics and Astronautics Parasite Drag • A simplified approach – parasite drag is mostly skin friction drag during cruise, plus a small separation drag • Second approach uses “Component Buildup Method”     Dmisc DL P ref fc c c wetc D subsonic C C S C FF Q S C 0    & 