过流截面突然扩大和突然缩小时局部阻力的测量与分析

在研究过流截面突然扩大或突然缩小的局部损失时 ,若采用两点法测量 ,因数据中包含沿程损失和粗大误差 ,故测量误差较大 .若采用三点法或四点法测量 ,虽然消除了沿程损失的影响 ,但仍然存在包含粗大误差的数据 ,直接影响测量结果的精确度 .本文分析了过流截面突然扩大和突然缩小时局部阻力的成因和理论计算公式 ,提出了测量判别比的概念 .利用这一概念 ,可剔除含粗大误差的数据 ,从而简化数据处理 ,提高测量结果的精确度 .

Measurement and analysis of local resistance on flow section expanded and narrowed suddenly

Having studied the local resistance on flow section expanded or narrowed suddenly, it may take data measured with 2_points method contained the resistance along the road and careless error, the error of mesurement is bigger. Measurement with 3_poits method or 4_poits method can remove the effect of resistance along the road, but there are data contained careless error and it has an effect on the accuracy of measurement.On the basis of discussing theoretic formulas and the reason of producing local resistance on flow section expanded and narrowed suddenly, the author has puts forward the concept of measurement distinguish coefficient. Accoding to the concept, datum contained careless error are rejected, data management is simplified and measure of precision of measurement result is raised.