﻿ 伞衣透气性对翼伞气动特性的影响<sup>*</sup>
 文章快速检索 高级检索

Effects of canopy's air permeability on parafoil aerodynamic performance
WANG Longfang, HE Weiliang, WANG Shichao
School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
Received: 2016-09-28; Accepted: 2016-12-30; Published online: 2017-01-18 18:10
Corresponding author. HE Weiliang, E-mail:heweiliang@buaa.edu.cn
Abstract: In order to enhance the flight performance of parafoil, the effects of canopy fabric's air permeability on parafoil aerodynamic performance were studied. The canopy external flow field was modeled by the incompressible Reynolds-averaged Navier-Stokes (RANS) equations, and the governing equations for porous medium domain with an additional momentum source term were established to model the canopy. For two material models with air permeability and one traditional model without air permeability, the aerodynamic characteristics and distribution of the two-dimensional and three-dimensional flow field were numerically simulated under steady condition. The results indicate that the canopy seepage velocity is available by solving the governing equations of porous medium domain, and the canopy external turbulivity increases sharply. The lift coefficient decreases and drag coefficient increases significantly when the canopy is made of large air permeability fabric, and furthermore the inner cavity pressure dropping affects the aerodynamic shape maintaining of parafoil. The lift coefficient is less than that in impermeable case at small angle of attack, and is greater than that in impermeable case at large angle of attack when the canopy is made of slight air permeability fabric because mild seepage velocity can delay the boundary layer separation at large angle of attack.
Key words: parafoil     air permeability     porous medium domain     numerical simulation     aerodynamic performance

1 数学模型 1.1 控制方程

 (1)

 (2)

1.2 透气性数学模型

 图 1 织物的横截面微观结构 Fig. 1 Cross-section microstructure of fabric

 (3)

 图 2 411蚕丝绸的试验数据和拟合曲线[20] Fig. 2 Test data and fitted curve of 411 silk[20]

 材料 a/(kg·(m2·s)-1) b/(kg·m-3) C1/m2 C2/m-1 411蚕丝绸 451.8 90.69 7.9×10-12 7.4×105 F111织物 9 036 1 813.8 3.95×10-13 1.48×107

 (4)

 (5)

 (6)

2 透气性对翼型气动性能的影响

 图 3 翼型周围网格 Fig. 3 Grid around airfoil
 图 4 多孔介质域和自由流动域 Fig. 4 Porous medium domain and unrestricted flow domain

 图 5 100 Pa压差下的透气速度矢量图 Fig. 5 Vectorgraph of air seepage velocity under 100 Pa differential pressure

 图 6 不同透气参数下的翼型升力系数和阻力系数 Fig. 6 Lift and drag coefficients of airfoil with different air permeability parameters

 图 7 迎角6°时翼型的压力云图与流线图 Fig. 7 Pressure contours and streamlines of airfoil at angle of attack 6°

 图 8 迎角6°时翼型的湍流黏度云图 Fig. 8 Turbulent viscosity contours of airfoil at angle of attack 6°
3 透气性对翼伞气动性能的影响

 图 9 仿真对象 Fig. 9 Simulation object

 图 10 计算域网格划分 Fig. 10 Grid partition of computational domain

 图 11 不同透气参数下的翼伞升力系数和阻力系数 Fig. 11 Lift and drag coefficients of parafoil with different air permeability parameters

3种透气性模型的阻力系数都随着迎角增加而增加，随着透气量增加, 阻力系数增加，F111织物的阻力系数稍大于不透气模型，411蚕丝绸的阻力系数相比于不透气模型增加了约50%。与二维翼型结果(见图 6)对比发现，考虑展向流动后不透气模型和F111织物的升力系数大幅下降，阻力系数大幅增加，这是由于三维效应引起的诱导迎角和诱导阻力引起的。除12°迎角外，411蚕丝绸的升力系数下降较少，阻力系数增加较少，有可能是由于411蚕丝绸伞衣附近的正常流动已经遭到严重破坏，展向流动的规模和影响都较小。总体上，随着透气量增大，翼伞的升力系数减小、阻力系数增大，与文献[21]中通过风洞试验得到的结论相同。

 图 12 迎角6°时上翼面压力云图 Fig. 12 Pressure contour of upper surface at angle of attack 6°

 图 13 迎角6°时F111织物伞衣的透气速度矢量图 Fig. 13 Vectograph of air seepage velocity of F111 fabric canopy at angle of attack 6°

 图 14 迎角6°时上翼面湍流黏度云图 Fig. 14 Turbulent viscosity contours of upper surface at angle of attack 6°
4 结论

1) 使用制作降落伞的材料411蚕丝绸制作翼伞时，升力系数大幅下降了40%左右，阻力系数大幅上升了约50%，气动性能较差，应使用透气量很小的材料制作翼伞。

2) 伞衣材料为411蚕丝绸时，内腔压力相比于驻点压力下降了约12%，使用透气量较大的材料制作伞衣不仅会降低翼伞系统的气动性能，而且会造成内腔泄压影响翼伞的充气成型，提高了气室塌陷的风险。

3) 100 Pa下透气量约为0.01 m3/(m2·s)的F111织物，升力系数在小迎角时稍小于不透气模型，在大迎角时稍大于不透气模型，较小的透气速度能在大迎角时延缓边界层分离。

4) 考虑伞衣的透气性以后，内腔形成了一个比较剧烈的湍流区，同时伞衣外表面的湍流黏度急剧增加。透气量达到0.21 m3/(m2·s)量级时，后缘处的附着流动已被破坏，对翼伞的气动性能造成不利影响。透气量的大小只影响伞衣外部湍流区距离伞衣的厚度，对伞衣表面的湍流区分布位置分布影响不大。

 [1] LINGARD J.The aerodynamics of gliding parachutes:A88-11201[R].London:RAS, 1986. [2] JANN T.Aerodynamic coefficients for a parafoil wing with arc anhedral-theoretical and experimental results:AIAA-2003-2106[R].Reston:AIAA, 2003. [3] 张顺玉, 秦子增, 张晓今. 可控翼伞气动力及雀降操纵力仿真计算[J]. 国防科技大学学报, 1999, 21 (3): 21–24. ZHANG S Y, QIN Z Z, ZHANG X J. The calculation of aerodynamics and flare control force for controlled parafoil[J]. Journal of National University of Defense Technology, 1999, 21 (3): 21–24. (in Chinese) [4] MATOS C, MAHALINGAM R, OTTINGER G, et al.Wind tunnel measurements of parafoil geometry and aerodynamics[C]//36th AIAA Aerospace Sciences Meeting.Reston:AIAA, 1998:1-11. [5] 贺卫亮. 利用风洞试验研究冲压翼伞的升阻特性[J]. 航空学报, 1999, 20 (Sup.): 75–77. HE W L. Study on lift-drag characteristic of ram air parachute in wind tunnel[J]. Acta Aeronautica et Astronautica Sinica, 1999, 20 (Sup.): 75–77. (in Chinese) [6] 战培国. 翼型伞风洞测力技术及工程估算方法研究[D]. 成都: 四川大学, 2004. ZHAN P G.The wind tunnel test technique and aerodynamic characteristics evaluation research on ram air parawings[D].Chengdu:Sichuan University, 2004(in Chinese). http://www.doc88.com/p-1116568662646.html [7] BALAJI R, MITTAL S, RAI A K. Effect of leading edge cut on the aerodynamics of ram-air parachutes[J]. International Journal for Numerical Methods in Fluids, 2005, 47 (1): 1–17. DOI:10.1002/(ISSN)1097-0363 [8] 李健. 前缘切口对冲压式翼伞的气动力影响[J]. 航天返回与遥感, 2005, 26 (1): 36–41. LI J. The aerodynamic influence of the cutter of the front edge of parafoil[J]. Spacecraft Recovery & Remote Sensing, 2005, 26 (1): 36–41. (in Chinese) [9] 李扬. 冲压式翼伞后缘下拉气动特性的数值研究[D]. 长沙: 国防科技大学, 2004. LI Y.Numerical simulation of ram-air parachutes with flap deflection[D].Changsha:National University of Defense Technology, 2004(in Chinese). http://cdmd.cnki.com.cn/Article/CDMD-90002-2005014332.htm [10] MOHAMMADI M A, JOHARI H. Computation of flow over a high-performance parafoil canopy[J]. Journal of Aircraft, 2010, 47 (4): 1338–1345. DOI:10.2514/1.47363 [11] 朱旭, 曹义华. 翼伞平面形状对翼伞气动性能的影响[J]. 航空学报, 2011, 32 (11): 1998–2007. ZHU X, CAO Y H. Numerical simulation of platform geometry effect on parafoil aerodynamic performance[J]. Acta Aeronauticaet Astronautica Sinica, 2011, 32 (11): 1998–2007. (in Chinese) [12] CAO Y H, ZHU X. Effects of characteristic geometric parameters on parafoil lift and drag[J]. Aircraft Engineering and Aerospace Technology, 2013, 85 (4): 280–292. DOI:10.1108/AEAT-Jun-2011-0096 [13] 朱旭, 曹义华. 翼伞弧面下反角、翼型和前缘切口对翼伞气动性能的影响[J]. 航空学报, 2012, 33 (7): 1189–1200. ZHU X, CAO Y H. Effects of arc-anhedral angle, airfoil and leading edge cut on parafoil aerodynamic performance[J]. Acta Aeronautica et Astronautica Sinica, 2012, 33 (7): 1189–1200. (in Chinese) [14] 张春, 杨倩, 袁蒙, 等. 冲压翼伞流场与气动操纵特性的数值模拟[J]. 航空动力学报, 2013, 28 (9): 2037–2043. ZHANG C, YANG Q, YUAN M, et al. Numerical simulation of flow field and hangding aerodynamic characteristics of ram-air parachute[J]. Journal of Aerospace Power, 2013, 28 (9): 2037–2043. (in Chinese) [15] KALRO V, TEZDUYAR T. A parallel 3D computational method for fluid-structure interactions in parachute systems[J]. Computer Methods in Applied Mechanics and Engineering, 2000, 190 (3-4): 321–332. DOI:10.1016/S0045-7825(00)00204-8 [16] 汪龙芳, 贺卫亮. 基于索膜有限元模型的翼伞气动变形仿真[J]. 北京航空航天大学学报, 2017, 43 (1): 47–52. WANG L F, HE W L. Parafoil aerodynamic deformation simulation based on cable-membrane finite element model[J]. Journal of Beijing University of Aeronautics and Astronautics, 2017, 43 (1): 47–52. (in Chinese) [17] 李万平. 计算流体力学[M]. 武汉: 华中科技大学出版社, 2004. LI W P. Computational fluid mechanics[M]. Wuhan: Huazhong University of Science and Technology Press, 2004. (in Chinese) [18] 王利荣. 降落伞理论与应用[M]. 北京: 宇航出版社, 1997. WANG L R. The theory and application of parachutes[M]. Beijing: China Astronautic Publishing House, 1997. (in Chinese) [19] HAN Y H, WANG Y W, YANG C X.Numerical methods for analyzing the aerodynamic characteristics of cross parachute with permeability[C]//Aerodynamic Decelerator Systems Technology Conference.Reston:AIAA, 2013:1-14. [20] 马衍富. 降落伞织物的透气性[J]. 产业用纺织品, 1987, 5 (1): 26–30. MA Y F. Permeability of parachute fabic[J]. Industrial Fabric, 1987, 5 (1): 26–30. (in Chinese) [21] DESABRAIS K J, BERGERON K, NYREN D, et al.Aerodynamic investigations of a ram-air parachute canopy and an airdrop system[C]//23rd AIAA Aerodynamic Decelerator Systems Technology Conferences.Reston:AIAA, 2015:1-17. [22] 杨雪, 余莉, 李允伟, 等. 环帆伞稳降阶段织物透气性影响数值模拟[J]. 空气动力学学报, 2015, 33 (5): 714–719. YANG X, YU L, LI Y W, et al. Numerical simulation of the effect of the permeability on the ringsail parachute in terminal descent stage[J]. Acta Aerodynamic Sinica, 2015, 33 (5): 714–719. (in Chinese)

#### 文章信息

WANG Longfang, HE Weiliang, WANG Shichao

Effects of canopy's air permeability on parafoil aerodynamic performance

Journal of Beijing University of Aeronautics and Astronsutics, 2017, 43(10): 2021-2029
http://dx.doi.org/10.13700/j.bh.1001-5965.2016.0764