基于黏性比例因子的锥形流量计最优锥角选择  

Optimal angle combinations of cone flow meter selection based on viscous stress scale factors

作　　者：刘伟光[1] 张涛[1] 徐英[1] 齐锋锋 李波[2] 

机构地区：[1]天津大学电气与自动化工程学院,天津300072 [2]天津航海仪器研究所,天津300072

出　　处：《仪器仪表学报》2015年第7期1497-1505,共9页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金(60974118)项目资助

摘　　要：锥形流量计的锥角参数是影响锥形流量计性能的重要参数,锥体前锥角和后锥角均有较大的取值范围,这造成供选择的锥角组合无限多。通过实验和传统的CFD仿真优化锥形流量计锥角工作量大,效率低。研究证明了锥角的变化引起的下游取压位置处的压力波动会导致锥形流量计流出系数的改变。根据流体力学本构方程理论定义了评价黏性应力对压力波动影响的黏性应力比例因子k1和k2,并得到结论：任一锥角组合锥形流量计下游取压位置处黏性比例因子k1和k2越大,锥形流量计的压力信号受到的干扰越大,对应的流出系数重复性和线性度误差越差,在低入口雷诺数状态下这种干扰尤为明显。基于黏性比例因子的具有不同锥角组合锥形流量计的性能预测结论是：β值在0.45~0.75的锥形流量计,前锥角为27.5°±2.5°,后锥角为65°±5°时锥形流量计的流出系数重复性和线性度误差好于其他的锥角组合。实验测试DN100口径,β值分别为0.45,0.5和0.65的9个不同锥角组合的锥形流量计,实验结论证明了基于黏性应力比例因子的锥形流量计锥角组合预测的准确性。Cone angle is a key factor affecting the performance of cone flow meter, but the large value range of the front and back cone angles leads to options of the cone angle combination are infinite. Cone angle combination optimizations by experimental and traditional CFD simulation methods are heavy in workload and inefficient in computation. Variation of cone angle combination causes pressure fluctuations in low pressure tapping position, which make discharge coefficient of cone flow meter change. According to the constitutive equation theory in fluid mechanics, viscous stress scale factors k1 and k2 are defined, and the factors can evaluate the viscous stress impact on pressure fluctuation. The flowing conclusions especially for the low inlet Reynolds numbers are drawn in the research. For any cone flow meter with different cone angle combinations, the pressure disturbances is rising with increase k1 and k2 . Meanwhile the corresponding reproducibility and linearity errors of discharge coefficient are worse. In the process of performance prediction of cone flow meters with different cone angles combinations based on viscous stress scale factors , the conclusions can be drawn that the cone flow meters with β value 0.45 - 0.75, the front cone angle 27.5°± 2.5° and back cone angle 65°±5° have good performance in reproducibility and linearity errors of discharge coefficient. The conclusions are verified in experiments.

关 键 词：锥形流量计 黏性比例因子 本构方程 锥角组合 

分 类 号：TH814[机械工程—仪器科学与技术]