Measurement and visualization of surface friction beneath jet flow over planar surface using liquid crystal coatings
-
摘要: 为了研究剪切敏感液晶（Shear Sensitive Liquid Crystal，SSLC）涂层在不同气流速度下用于测量和显示壁面摩擦力场的能力，应用SSLC涂层对不同速度下平板表面亚声速射流的摩擦力矢量场进行了测量，对带有激波单元的超声速射流摩擦力场及其动态特性进行了流动显示。研究结果表明：在定量测量方面，SSLC涂层能够在宽量程范围内快速、高分辨率地测量射流摩擦力矢量场，可用于射流摩擦力场随射流速度的变化特性研究；在流动显示方面，SSLC涂层可用于显示超声速射流的菱形激波单元等流场结构及其动态变化特性。Abstract: The ability of Shear Sensitive Liquid Crystal （SSLC） coatings to measure and visualize surface friction fields is studied. Liquid crystal coatings are used to measure surface friction beneath the subsonic jet flow over a planar surface at various jet velocities, and to visualize unsteady surface friction fields of supersonic jet flow with shock cells. Experimental study shows that in terms of quantitative measurement, a single liquid crystal coating is able to measure surface friction rapidly with a high resolution and a wide range, and is also suitable for studying the variation of surface friction with the jet flow velocity. In the aspect of flow visualization, liquid crystal coatings provide another way for visualizing the flow field structures such as diamond shock cells of the supersonic jet flow and the unsteady characteristics of the shock cells.
-
Key words:
- Shear Sensitive Liquid Crystal /
- surface friction /
- measurement /
- visualization /
- jet flow /
- shock waves
-
图 2 不同喷压比下的液晶涂层颜色照片 （ϕC = −18.3°）
Figure 2. Liquid crystal coating color images at different RNP values （ϕC = −18.3°）
图 3 不同喷压比下液晶涂层测量的摩擦力矢量场
Figure 3. Wall shear stress vector field measured by liquid crystal coating at different RNP values
-
[1] 丁超,史志伟,玉曜瑜. 基于油膜干涉法的表面摩擦应力测量技术研究[J]. 实验力学,2011,26(6):707-714.DING C,SHI Z W,YU Y Y. Study of skin friction stress measurement technique based on oil film interferometry[J]. Journal of Experimental Mechanics,2011,26(6):707-714. [2] 马洪强,高贺,毕志献. 高超声速飞行器相关的摩擦阻力直接测量技术[J]. 实验流体力学,2011,25(4):83-88. doi: 10.3969/j.issn.1672-9897.2011.04.016MA H Q,GAO H,BI Z X. Direct measurement of skin friction for hypersonic flight vehicle[J]. Journal of Experiments in Fluid Mechanics,2011,25(4):83-88. doi: 10.3969/j.issn.1672-9897.2011.04.016 [3] 吕治国,李国君,赵荣娟,等. 激波风洞高超声速摩阻直接测量技术研究[J]. 实验流体力学,2013,27(6):81-85. doi: 10.3969/j.issn.1672-9897.2013.06.015LÜ Z G,LI G J,ZHAO R J,et al. Direct measurement of skin friction at hypersonic shock tunnel[J]. Journal of Experiments in Fluid Mechanics,2013,27(6):81-85. doi: 10.3969/j.issn.1672-9897.2013.06.015 [4] 史云龙. 高超声速风洞模型表面摩阻测量技术研究 [D]. 绵阳: 中国空气动力研究与发展中心, 2015.SHI Y L. The research of model skin friction measurement technology in hypersonic wind tunnel [D]. Mianyang: China Aerodynamics Research and Development Center, 2015. [5] NAUGHTON J W,SHEPLAK M. Modern developments in shear-stress measurement[J]. Progress in Aerospace Sciences,2002,38(6-7):515-570. doi: 10.1016/S0376-0421(02)00031-3 [6] REDA D C,MURATORE J J Jr. Measurement of surface shear stress vectors using liquid crystal coatings[J]. AIAA Journal,1994,32(8):1576-1582. doi: 10.2514/3.12146 [7] REDA D C,WILDER M C,FARINA D J,et al. New methodology for the measurement of surface shear stress vector distributions[J]. AIAA Journal,1997,35(4):608-614. doi: 10.2514/2.165 [8] REDA D C,WILDER M C,MEHTA R D,et al. Measurement of continuous pressure and shear distributions using coating and imaging techniques[J]. AIAA Journal,1998,36(6):895-899. doi: 10.2514/2.484 [9] REDA D, MURATORE J Jr. A new technique for the measurement of surface shear stress vectors using liquid crystal coatings[C]//Proc of the 32nd Aerospace Sciences Meeting and Exhibit. 1994. doi: 10.2514/6.1994-729 [10] FUJISAWA N, FUNATANI S, KOSAKA S. Measurement of shear-stress distribution by liquid-crystal coating[C]//Proc of SPIE 5058, Optical Technology and Image Processing for Fluids and Solids Diagnostics. 2003. doi: 10.1117/12.509840 [11] FUJISAWA N,OGUMA Y,NAKANO T. Measurements of wall-shear-stress distribution on an NACA0018 airfoil by liquid-crystal coating and near-wall particle image velocimetry (PIV)[J]. Measurement Science and Technology,2009,20(6):065403. doi: 10.1088/0957-0233/20/6/065403 [12] ZHAO J S,SCHOLZ P,GU L X. Color change characteristics of two shear-sensitive liquid crystal mixtures (BCN/192, BN/R50C) and their application in surface shear stress measurements[J]. Chinese Science Bulletin,2011,56(27):2897-2905. doi: 10.1007/s11434-011-4673-y [13] ZHAO J S,SCHOLZ P,GU L X. Measurement of surface shear stress vector distribution using shear-sensitive liquid crystal coatings[J]. Acta Mechanica Sinica,2012,28(5):1261-1270. doi: 10.1007/s10409-012-0144-1 [14] 陈星,文帅,潘俊杰,等. 三角翼标模摩擦阻力测量的高超声速风洞实验与数据确认[J]. 气体物理,2017,2(2):54-63. doi: 10.19527/j.cnki.2096-1642.2017.02.007CHEN X,WEN S,PAN J J,et al. Delta wing model skin friction measurement test and data confirming in hypersonic wind tunnel[J]. Physics of Gases,2017,2(2):54-63. doi: 10.19527/j.cnki.2096-1642.2017.02.007 [15] ZHAO J S. Measurement of wall shear stress in high speed air flow using shear-sensitive liquid crystal coating[J]. Sensors,2018,18(5):1605. doi: 10.3390/s18051605 [16] ZHAO J S. Investigation on wall shear stress measurement in supersonic flows with shock waves using shear-sensitive liquid crystal coating[J]. Aerospace Science and Technology,2019,85:453-463. doi: 10.1016/j.ast.2018.12.034 [17] 赵吉松. 基于剪切敏感液晶涂层的壁面摩擦力矢量场全局测量方法[J]. 航空科学技术,2019,30(2):53-59.ZHAO J S. Measurement methods of wall shear stress vector field over planar surface using shear-sensitive liquid crystal coating[J]. Aeronautical Science and Technology,2019,30(2):53-59. [18] 赵吉松. 平板表面薄圆柱绕流摩擦力矢量场全局测量[J]. 空气动力学学报,2020,38(1):27-34. doi: 10.7638/kqdlxxb-2018.0200ZHAO J S. Global measurement of wall shear stress vector field over flat plate around thin cylinder[J]. Acta Aerodynamica Sinica,2020,38(1):27-34. doi: 10.7638/kqdlxxb-2018.0200 [19] ZHAO J S,ZHANG J M,WANG B Q. A learning-based approach for solving shear stress vector distribution from shear-sensitive liquid crystal coating images[J]. Chinese Journal of Aeronautics,2021,35(4):55-65. doi: 10.1016/j.cja.2021.04.019 [20] 赵吉松. 基于剪切敏感液晶涂层的流道内壁面摩擦力场测量方法: CN109489934B[P]. 2021-04-06.ZHAO J S. Method for measuring friction field on inner wall of flow passage based on shear sensitive liquid crystal coating: CN109489934B[P]. 2021-04-06. [21] 赵吉松, 朱博灵, 沈臻祺, 等. 一种应用液晶涂层和深度学习算法测量摩擦力场的方法: CN112326187A[P]. 2021-02-05.ZHAO J S, ZHU B L, SHEN Z Q, et al. Method for measuring friction field by applying liquid crystal coating and deep learning algorithm: CN112326187A[P]. 2021-02-05. [22] 赵吉松, 李畅, 朱博灵, 等. 一种适用于任意照射和观测方向的液晶涂层颜色标定方法: CN112326186A[P]. 2021-02-05.ZHAO J S, LI C, ZHU B L, et al. Liquid crystal coating color calibration method suitable for any irradiation and observation direction: CN112326186A[P]. 2021-02-05. [23] TLC products for use in research and testing applications[EB/OL]. [2021-08-20]. https://www.lcrhallcrest.com/wp-content/uploads/2019/02/RD-TLC-Products-for-use-in-Research-Testing-Applications.pdf. -
下载:
点击查看大图
图(4)
计量
- 文章访问数: 2116
- HTML全文浏览量: 148
- PDF下载量: 48
- 被引次数: 0
