上游单90°弯头对内锥流量计性能的影响

Effects of Upstream Pipe Single 90° Elbow on the Performance Characteristics of Cone Flowmeters

为提高对内锥流量计安装与使用条件的认识，设计100mm口径的样机一台，开展了上游单个90。弯头影响的实验研究．实验介质为常温水，雷诺数范围为0．13×10^5～5．1×10^5．实验方案分基线实验和上游不同直管段长度的单弯头实验，节流比分别为0．45、0．55、0．65和0．85，累计进行了15组实验．利用平均流出系数相对误差及附加不确定度作为安装条件的主要评价标准，给出了上游单个90°弯头实验的直管段建议长度，并与国外研究结论进行了比较。得出节流比分别为0．45、0．55和0．65时，前直管段建议长度分别为2D、1D和3D；节流比为0．85时，前直管段长度为0D、1D、2D和5D时，弯头的影响均不能忽略．

To acquire a deep knowledge of installation requirements and application conditions,a prototype with 100 mm diameter was designed and the effects of upstream pipe single 90° elbow on the performance characteristics of cone flowmeters was carried out here. The experiment medium was water of normal temperature and Reynolds number range of 0.13× 10^5-5.1 × 10^5. The experiment scheme included the baseline experiments and one single elbow effects experiments with different upstream straight pipe length. The equivalent diameter ratio was of 0.45,0.55,0.65 and 0.85 respectively. There were 15 groups of experiments in all. The relative error of the averaged discharge coefficient and the additive uncertainty were the key evaluating criteria. Comparing with the foreign study conclusions,suggestions on installation requirements were given for the upstream single 90° elbow effects. For cone flowmeters with the equivalent diameter ratio of 0.45, 0.55 and 0.65 ,the proposed strength of upstream pipes is 2D, 1D and 3D respectively. While the straight length of the up- stream pipe is 0D, 1D,2D and 5D respectively,the effects of upstream pipe single elbow on the performance characteristics of cone flowmeter with ratio of 0.85 can not be neglected.