CAJ | 학술논문

在光滑明渠紊动水流的研究中，黏性底层具有重要的作用，壁面剪切应力与涡量均源于此流区。由于充分发展明渠紊流的黏性底层的物理尺度在0.1 mm量级，常规方法难以实际测量该区内的速度分布。本文构建了测量黏性底层的高分辨率HR-PTV与测量全流区的普通PIV的耦合测量系统，对光滑明渠紊流黏性底层的流动特性进行了研究。HR-PTV系统采用阈值递增法、灰度截断、椭圆度与充实度指标等方法进行图像处理得到清晰的粒子图像；使用匹配几率法对粒子坐标进行匹配，计算粒子速度。得到了明渠紊流黏性底层（0.3 mm以内）的平均流速、紊动强度、偏态系数和峰度系数的垂线分布。从拟合的平均流速分布得出摩阻流速u*，结果与牛顿流体本构方程一致；黏性底层与全流区的时均流速、紊动强度和雷诺应力均能用拟合所得的u*合理无量纲化，并能光滑连接，表明由此得出的u*适用于全流区。将明渠紊流的各种分布与封闭槽道流DNS数据进行对比，验证了HR-PTV在黏性底层所得各阶速度矩的准确性。
재광활명거문동수류적연구중，점성저층구유중요적작용，벽면전절응력여와량균원우차류구。유우충분발전명거문류적점성저층적물리척도재0.1 mm량급，상규방법난이실제측량해구내적속도분포。본문구건료측량점성저층적고분변솔HR-PTV여측량전류구적보통PIV적우합측량계통，대광활명거문류점성저층적류동특성진행료연구。HR-PTV계통채용역치체증법、회도절단、타원도여충실도지표등방법진행도상처리득도청석적입자도상；사용필배궤솔법대입자좌표진행필배，계산입자속도。득도료명거문류점성저층（0.3 mm이내）적평균류속、문동강도、편태계수화봉도계수적수선분포。종의합적평균류속분포득출마조류속u*，결과여우돈류체본구방정일치；점성저층여전류구적시균류속、문동강도화뢰낙응력균능용의합소득적u*합리무량강화，병능광활련접，표명유차득출적u*괄용우전류구。장명거문류적각충분포여봉폐조도류DNS수거진행대비，험증료HR-PTV재점성저층소득각계속도구적준학성。
Viscous sublayer has an important role in open channel flow, and shear stress and vorticity are both derived from this area. Due to its physical dimensions is in the order of 0.1 mm in fully developed tur-bulence flow, common measurement methods are difficult to observe viscous sub layer. This paper illus-trates a High-Resolution PTV coupled PIV system built for measuring the inner and outer layer of open channel flow. The threshold iteration increasing method,gray truncation method,elliptical indicator and fill-ing indicator are used for High-Resolution PTV image processing. Probability matching method is used for matching the particles and calculating the velocities. The mean velocity, turbulence intensity, skewness and kurtosis distribution in viscous sublayer are got in open channel flows. The friction velocities were got by fit-ting the mean velocity distribution in viscous sublayer, and the results are consistent with the Newtonian fluid constitutive equation. The mean velocity, turbulence intensity and Reynolds stress of inner and outer layer can all be converted into reasonable dimensionless by the friction velocity from fitting the mean veloci-ty distribution in viscous sublayer, and data in the share region between HR-PTV and PIV can connect smoothly. Various distribution of open channel flows were compared with the data from direct numerical sim-ulations in channel flow to verify the results.