Abstract Oil and gas production industries use large (diameter > 0.8 m) ultrasonic flow meters (USMs) to measure exhaust gas from flare stacks, emissions from smokestacks, flow of natural gas, etc. Since most flow laboratories do not have compressors with sufficient flow capacity (>10 kg/s) to calibrate large flow meters, calibrations are performed using the blow-down method where flow is generated by discharging high pressure tanks, leading to significant flow transients. We used an array of critical flow venturis (CFVs) in a blow-down facility to calibrate a large (D = 89.5 cm) 8-path ultrasonic flow meter. The flow transients associated with the blow-down process caused large spatial and temporal variations in temperature that dominated (40%–67%) the uncertainty budget. Our uncertainty analysis accounts for transient-generated uncertainties and provides guidelines for improving blow-down calibrations of large flow meters.

中文翻译：

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大型超声波流量计的排污校准

摘要 石油和天然气生产行业使用大型（直径 > 0.8 m）超声波流量计 (USM) 来测量火炬烟囱的废气、烟囱的排放、天然气流量等。由于大多数流量实验室没有足够流量的压缩机容量 (>10 kg/s) 以校准大型流量计，使用排污方法进行校准，其中通过排放高压罐产生流量，导致显着的流量瞬变。我们在排污设施中使用了一系列临界流量文丘里管 (CFV) 来校准大型 (D = 89.5 cm) 8 路超声波流量计。与排污过程相关的流动瞬变导致温度的巨大空间和时间变化，主导（40%–67%）不确定性预算。