不同雷诺数下翼型气动特性及层流分离现象演化

doi:10.7527/S1000-6893.2016.0257

Abstract

Abstract:

Due to the outstanding air viscosity at low Reynolds number, laminar separation is common on airfoil surface, resulting in the deterioration of aerodynamic characteristics compared with those at general Reynolds number. The numerical simulation technology for solving the unsteady compressible Navier-Stokes equations with the preconditioning Roe method and oil flow visualization in the low Reynolds number low turbulence wind tunnel is used to investigate the aerodynamic characteristics and flow structures of the FX63-137 airfoil at different Reynolds numbers. The main conclusions are described in the following. Two clear oil accumulation lines are captured in laminar separation flow through oil flow visualization. Numerical results show that the lines are the primary and secondary separation lines respectively. The qualitative and quantitative results of the two technologies are in good agreement, showing the effectiveness and credibility of the research method in this paper. Airfoil dynamic characteristics and laminar flow separation structures change significantly with the decrease of Reynolds numbers from 500 000 to 20 000. With the sharp increase of drag coefficient and reduction of lift coefficient, the time-average flow structure develops from attachment to classical long laminar separation bubble, and eventually evolves into trailing-edge laminar separation bubble. Correspondingly, two types of separation bubbles are significantly different in unsteady flow. There are different critical Reynolds numbers for the drag coefficient and lift coefficient. The reason is that the drag coefficient increases as the long laminar separation bubble can increase the pressure drag, while the lift coefficient sharply decreases as the appearance of trailing-edge laminar separation bubble can cause the decrease of equivalent airfoil camber. Unsteady results display that it is because of the generation and shedding of periodic vortex on airfoil surface, the lift coefficient has periodic fluctuation. When the main vortex is about to shed, the streamlines are near the trailing edge, and the lift coefficient reaches the peak. When the fluid is rolled up to generate the secondary vortex, the streamlines separate significantly, and the lift coefficient reduces to the valley.

Key words: low Reynolds number, aerodynamic characteristics, long laminar separation bubble, trailing-edge laminar separation bubble, unsteady

CLC Number:

V211.3

LIU Qiang, LIU Qiang, BAI Peng, LI Feng. Aerodynamic characteristics of airfoil and evolution of laminar separation at different Reynolds numbers[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2017, 38(4): 120338-120338.

References

[1] 李锋, 白鹏, 石文, 等. 微型飞行器低雷诺数空气动力学[J]. 力学进展, 2007, 37(2):257-268. LI F, BAI P, SHI W, et al. Micro air vehicle aerodynamics at low Reynolds number[J]. Advances in Mechanics, 2007, 37(2):257-268 (in Chinese).
[2] 白鹏, 崔尔杰, 李锋, 等. 对称翼型低雷诺数小迎角升力系数非线性现象研究[J]. 力学学报, 2006, 38(1):1-8. BAI P, CUI E J, LI F, et al. Study of the non-linear lift coefficient of the symmetric airfoil at low Reynolds number near the 0° angle of attack[J]. Chinese Journal of Theoretical and Applied Mechanics, 2006, 38(1):1-8 (in Chinese).
[3] MUNDAY P M, TAIRA K, SUWA T, et al. Nonlinear lift on a triangular airfoil in low-reynolds-number compressible flow[J]. Journal of Aircraft, 2015, 52(3):924-931.
[4] MUELLER T J. The influence of laminar separation and transition on low Reynolds number airfoil hysteresis[J]. Journal of Aircraft, 1985, 22(9):763-770.
[5] YANG Z, IGARASHI H, MARTIN M, et al. An experimental investigation on aerodynamic hysteresis of a low-reynolds number airfoil:AIAA-2008-0315[R]. Reston:AIAA, 2008.
[6] HORTON H P. Laminar separation bubbles in two and three dimensional incompressible flow[D]. London:Queen Mary University of London, 1968.
[7] 白鹏, 崔尔杰, 周伟江, 等. 翼型低雷诺数层流分离泡数值研究[J]. 空气动力学学报, 2006, 24(4):416-424. BAI P, CUI E J, ZHOU W J, et al. Numerical simulation of laminar separation bubble over 2D airfoil at low Reynolds number[J]. Acta Aerodynamica Sinica, 2006, 24(4):416-424 (in Chinese).
[8] KOJIMA R, NONOMURA T, OYAMA A, et al. Large-eddy simulation of low-Reynolds-number flow over thick and thin naca airfoils[J]. Journal of Aircraft, 2013, 50(1):187-196.
[9] MUELLER T J, BATIL S M. Experimental studies of separation on a two-dimensional airfoil at low Reynolds numbers[J]. AIAA Journal, 1982, 20(4):457-463.
[10] ANANDA G K, SUKUMAR P P, SELIG M S. Measured aerodynamic characteristics of wings at low Reynolds numbers[J]. Aerospace Science & Technology, 2015, 42:392-406.
[11] 吴鋆, 王晋军, 李天. NACA0012翼型低雷诺数绕流的实验研究[J]. 实验流体力学, 2013, 27(6):32-38. WU J, WANG J J, LI T. Experimental investigation on low Reynolds number behavior of NACA0012 airfoil[J]. Journal of Experiments in Fluid Mechanics, 27(6):32-38 (in Chinese).
[12] TORRES G E, MUELLER T J. Low aspect ratio aerodynamics at low Reynolds numbers[J]. AIAA Journal, 2004, 42(5):865-873.
[13] YANG Z, HAAN F L, HUI H, et al. An experimental investigation on the flow separation on a low-Reynolds-number airfoil:AIAA-2007-0275[R]. Reston:AIAA, 2007.
[14] OLSON D A, KATZ A W, NAGUIB A M, et al. On the challenges in experimental characterization of flow separation over airfoils at low Reynolds number[J]. Experiments in Fluids, 2013, 54(2):1-11.
[15] GROSS A, FASEL H F. Numerical investigation of separation for airfoils at low reynolds numbers:AIAA-2010-4736[R]. Reston:AIAA, 2010.
[16] BAGADE P M, KRISHNAN S B, SENGUPTA T K. DNS of low reynolds number aerodynamics in the presence of free stream turbulence[J]. Journal of Aerospace Engineering, 2015, 4(1):20-34.
[17] CADIEUX F, DOMARADZKI J A, SAYADI T, et al. Direct numerical simulation and large eddy simulation of laminar separation bubbles at moderate Reynolds numbers[J]. Journal of Fluids Engineering, 2014, 136(6):386-407.
[18] CHOUDHRY A, ARJOMANDI M, KELSO R. A study of long separation bubble on thick airfoils and its consequent effects[J]. International Journal of Heat & Fluid Flow, 2015, 52(1):84-96.
[19] CHEN Z J, QIN N, NOWAKOWSKI A F. Three-dimensional laminar-separation bubble on a cambered thin wing at low Reynolds numbers[J]. Journal of Aircraft, 2013, 50(1):152-163.
[20] CHEN Z J, QIN N. Planform effects for low-reynolds-number thin wings with positive and reflex cambers[J]. Journal of Aircraft, 2013, 50(3):952-964.
[21] MA D L, ZHAO Y, QIAO Y, et al. Effects of relative thickness on aerodynamic characteristics of airfoil at a low Reynolds number[J]. Chinese Journal of Aeronautics, 2015, 28(4):1003-1015.
[22] 白鹏, 李锋, 詹慧玲, 等. 翼型低Re数小迎角非线性非定常层流分离现象研究[J]. 中国科学:物理学力学天文学, 2015, 45(2):24703. BAI P, LI F, ZHAN H L, et al. Study about the non-linear and unsteady laminar separation phenomena around the airfoil at low Reynolds number with low incidence[J]. Scientia Sinca-Physica Mechanica Astronomica, 2015, 45(2):24703 (in Chinese).
[23] 刘强, 刘周, 白鹏, 等. 低雷诺数翼型蒙皮主动振动气动特性及流场结构数值研究[J]. 力学学报, 2016, 48(2):269-277. LIU Q, LIU Z, BAI P, et al. Numerical study about aerodynamic characteristics and flow field structures for a skin of airfoil with active oscillation at low Reynolds number[J]. Chinese Journal of Theoretical and Applied Mechanics, 2016, 48(2):269-277 (in Chinese).
[24] KERMANI M J, PLETT E G. Modified entropy correction formula for the roe scheme:AIAA-2001-0083[R]. Reston:AIAA, 2001.
[25] VENKATAKRISHNAN V. On the accuracy of limiters and convergence to steady state solutions:AIAA-1993-0880[R]. Reston:AIAA, 1993.
[26] WEISS J M, SMITH W A. Preconditioning applied to variable and constant density flow[J]. AIAA Journal, 1995, 33(11):2050-2057.
[27] 白晓征, 郭正, 刘君. 黏性极低速流动的预处理方法研究[J]. 空气动力学学报, 2009, 27(4):451-455. BAI X Z, GUO Z, LIU J. Study of preconditioning methods for very low speed viscous flows[J]. Acta Aerodynamica Sinica, 2009, 27(4):451-455 (in Chinese).
[28] 张强, 杨永. 基于迎风隐格式的全速域数值算法研究[J]. 西北工业大学学报, 2007, 25(6):768-772. ZHANG Q, YANG Y. Applying Weiss-Smith preconditioning to low Mach number flow with implicit upwind scheme[J]. Journal of Northwestern Polytechnical University, 2007, 25(6):768-772 (in Chinese).
[29] LUO H, BAUM J D, LOHNER R. A fast, matrix-free implicit method for compressible flows on unstructured grids[J]. Journal of Computational Physics, 1998, 146(2):664-690.
[30] 蒋跃文, 叶正寅, 王刚. 基于非结构网格的高效求解方法研究[J]. 计算力学学报, 2012, 29(2):217-223. JANG Y W, YE Z Y, WANG G. Efficient solution of Euler/N-S equations on unstructured grids[J]. Chinese Journal of Computational Mechanics, 2012, 29(2):217-223 (in Chinese).
[31] MCGRANAHAN B D, SELIG M S. Surface oil flow measurements on several airfoils at low Reynolds numbers:AIAA-2003-4067[R]. Reston:AIAA, 2003.

Aerodynamic characteristics of airfoil and evolution of laminar separation at different Reynolds numbers

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