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由节流装置与差压变送器及显示仪表组成的差压式流量计,在目前国内外流量测量中占有重要位置,使用最为广泛。国际标准ISO-5167和国家标准GB-2624-81是节流装置设计的基本依据。其提供的流量基本方程式为 M=(ΔPρ)～(O.003996α_nγ_RCεd～2) (1)式中,质量流量M的大小,与被测介质工况有着密切的联系。节流装置设计时,α_n、γ_RC、ε、d、ρ诸参数,都是在额定工况参数——流体平均温度t_0平均压力P_0和常用雷诺数R_eDeom之下确定的。但是,测量过程中流体温度t、压力P和雷诺数R_eD并非稳定,特别是开环计量和检测时,工况变化可达百分之几十,给测量结果带来难以接受的误差。如下文列举的空气测量实例,当t和P变化20%时,引入误差分别为9.956%和10.87%。而雷诺数在流量量
By the throttle device and the differential pressure transmitter and display instrument composed of differential pressure flowmeter, flow measurement at home and abroad occupy an important position, the most widely used. International standard ISO-5167 and national standard GB-2624-81 are the basic design of throttling device. The basic flow equation provided is M = (ΔPρ) ~ (O.003996α_nγ_RCεd ~ 2) (1) In the formula, the mass flow rate M is closely related to the measured medium condition. When designing the throttling device, the parameters α_n, γ_RC, ε, d and ρ are all determined under the rated working condition parameters - the mean fluid temperature t_0 average pressure P_0 and the common Reynolds number R_eDeom. However, the fluid temperature t, the pressure P and the Reynolds number R_eD are not stable during the measurement. In particular, when the open-loop measurement and measurement are carried out, the change of working conditions can reach several tens of percent, which brings unacceptable errors to the measurement results. As the air measurement examples listed below, when the t and P changes by 20%, the introduced errors are 9.956% and 10.87%, respectively. The Reynolds number in the flow