样本容量对明渠垂线流速分布对数公式拟合的影响  

Impact of sample size on the log-law fitting of vertical velocity distribution in open-channel flows

作　　者：陈兴伟[1,2] 林炳青[1] 林木生[1] 

机构地区：[1]福建师范大学地理科学学院,福建福州350007 [2]湿润亚热带山地生态国家重点实验室培育基地,福建福州350007

出　　处：《水利水电科技进展》2013年第5期35-37,94,共4页Advances in Science and Technology of Water Resources

基　　金：国家自然科学基金(50979015)

摘　　要：针对明渠垂线流速分布测量样本容量对对数公式拟合的影响问题,通过水槽试验,应用激光多普勒测速仪,在0.2倍水深内布设110个点进行垂线流速测量;按相对等距原则,从110个测量数据中共生成11组不同样本容量的流速系列进行统计分析。结果表明:试验测得的垂线流速分布符合对数公式;对数公式拟合所得的摩阻流速、积分常数及其统计变量相关系数和变差系数随样本容量大小的变化而变化,当样本容量逐渐变大时,渐渐趋于稳定,符合统计理论的大数定律;合理反映垂线流速分布变化的试验,其测点需要一定的样本容量;试验得到的垂线流速在间距分布比较均匀的条件下,0.2倍水深内所需样本容量为50左右。In order to investigate the impact of sample size for open channel vertical velocity distribution measurement on the log-law fitting,110 measuring points were arranged within a 0.2 times water depth in flume experiments.The vertical velocities were collected with a laser Doppler anemometer（LDA）.Based on the relative equidistance principle,11 sets of velocity of different sample sizes generated from the 110 velocity measurements were used to conduct statistical analysis.The results show that the vertical velocity distributions agree well with the log-law formula.The fitted friction velocity,integral constant,statistical variables and variation coefficient obtained from log-law fitting vary with the size of the samples.With the sample size increase,these parameters tend to be stable which is consistent with the statistical law of large numbers.It can be concluded that a certain sample size is needed at its measuring point to accurately reveal the vertical velocity distribution.According to the present test,a sample size of about 50 is necessary for a reasonable fitting result within 0.2 times water depth when the measurements are uniform distributed with same interval in the vertical direction.

关 键 词：明渠流 垂线流速 流速分布 对数公式 样本容量 

分 类 号：TV133[水利工程—水力学及河流动力学]