Numerical simulation of gurney flaps lift-enhancement on a low reynolds number airfoil

• Published in: Science China. Technological sciences Vol. 60; no. 10; pp. 1548 - 1559
• Main Authors: He, Xi, Wang, JinJun, Yang, MuQing, Ma, DongLi, Yan, Chao, Liu, PeiQing
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.10.2017; Springer Nature B.V
• Subjects: Aerodynamics; Air flow; Angle of attack; Boundary layer; Boundary layer transition; Computational fluid dynamics; Computer simulation; Drag; Engineering; Flight vehicles; Fluid flow; Gurney襟翼; Laminar flow; Lift; Low Reynolds number; Mathematical models; Navier-Stokes equations; Pressure; Pressure distribution; Reynolds averaged Navier-Stokes method; Shear stress; Simulation; Stokes; Stress concentration; Trailing edge flaps; 数值模拟; 气动性能; 翼型设计; 表面压力分布; 边界层转捩; 雷诺兹数; gurney flaps; low reynolds number; lift-enhancement; numerical simulation
• ISSN: 1674-7321; 1869-1900
• DOI: 10.1007/s11431-017-9085-4

Two-dimensional steady Reynolds-averaged Navier-Stokes （RANS） equations with transition shear stress transport （SST） model were solved to investigate the effects of Gumey flaps on the aerodynamic performance of a low Reynolds number airfoil. This airfoil was designed for flight vehicles operating at 20 km altitude with freestream velocity of 25 rn/s. The chord length （C） of this airfoil is 5 m and the corresponding Reynolds number is 7.76× 10^5. Gurney flaps with the heights ranging from 0.25%C to 3%C were investigated. It has been shown that Gurney flaps can enhance not only the prestall lift but also lift-to-drag ratio in a certain range of angles of attack. Specially, at cruise angle of attack （3°）, Gurney flap with the height of 0.5%C can increase lift-to-drag ratio and lift coefficient by 1.6% and 12.8%, respectively. Furthermore, the mechanisms of Gumey flaps to improve the aerodynamic performance were illustrated by analyzing the surface pressure distribution, streamlines and trailing-edge flow structure for this low Reynolds number airfoil. Specially, distinguished from some other numerical researches, the flow details such as the laminar separation bubble and transition phenomena for low Reynolds number airfoil with Gumey flaps were investigated and it was found that Gurney flaps can delay the transition onset position at small angles of attack （≤2°）. However, with the increase of angles of attack, Gurney flaps will promote the boundary layer transition.