管壁差压式涡街流量计测量影响因素分析

为了提高涡街流量计的抗干扰性和稳定性并保证测量精度，提出了一种基于管壁差压的旋涡频率检测新方法.在水和空气不同管内流动介质的情况下进行了系统实验.应用旋涡动力学和流体阻抗法，分析了取压位置和引压管频率特性因素对该方法测量性能的影响.实验结果表明，在旋涡发生体下游的一定距离内，取压位置对该方法的斯特劳哈尔数和仪表系数的影响很小，较靠近旋涡发生体迎流面的地方可测流量下限低.引压管的长度应尽量短，并且保证其固有频率与涡街频率相差较大.该方法简便可靠，适应性强，测量下限低.

Impact analysis of vortex flowmeter measured with duct-wall differential pressure method

In order to improve the anti-disturbance ability and stability of vortex flowmeter without influencing its accuracy,a new method by using duct-wall differential pressure was proposed to measure vortex frequency.Systematic experiments were performed in the cases of water and air respectively.Based on the theory of vortex dynamics and fluidic impedance,the impacts of pressure-sampling position and joining pipe's frequency response on measured performances of the method were investigated.The experimental results show that pressure-sampling position has little effect on the Strouhal number and meter coefficient in a certain vicinity downstream from the bluff body.The nearer the pressure-sampling position is to the bluff body,the smaller is the minimum measurable flowrate.The joining pipe length should be made as short as possible and its natural frequency must be far from the vortex frequency.The method is simple and reliable,has strong adaptability,and reduces the minimum measurable flow limit.