Tsyh Tyan Yeh

An intelligent ultrasonic flowmeter for improved flow measurement and flow calibration facility

An increasing need for reduced uncertainty has forced metrologists to look for novel ways to improve the calibration standards for flow. The NIST is experimenting with the use of an advanced ultrasonic flowmeter (AUFM) to improve flow measurement and to detect the dynamic properties of calibration facilities. Ultrasonic technology is evolving rapidly and technical advances have significantly improved flow measurement in continuous industrial processes. The AUFM couples multipath ultrasonic sensing capabilities with pattern recognition software to predict likely flow fields and their probability of existence. The knowledge encoded in the AUFM is derived from training exercises that use computational fluid dynamics and experimental results to teach a flow field recognizer (FFR) via a learning algorithm. A four-path ultrasonic flowmeter prototype has been used to demonstrate the AUFM operational principle. Results showed that the four-path meter can successfully identify flow patterns among several selected flow fields. The results also indicated that the ability of the FFR to identify flow patterns increases as the accuracy of the sensor increases, while decreases as the number of flow patterns considered increases. In addition to being used as a flow diagnostic tool, the AUFM could prove beneficial in field applications where installation effects can lead to gross errors when ultrasonic signals are evaluated using conventional integration techniques.

An Uncertainty Analysis of a NIST Hydrocarbon Liquid Flow Calibration Facility

This paper presents the uncertainty characterization of NIST’s new hydrocarbon liquid flow calibrator (HLFC). This facility uses a passive piston prover technique where fluid is driven by pumps while the measuring piston is passively stroked through the calibration interval. This facility is typically operated using MIL-C-7024C fluid (also known as Stoddard solvent – a surrogate liquid for JP-4 and JP-5 jet fuels), but using a variety of other fluids offers a wider range of measurements. The range of flows for this facility is 0.19 to 5.7 liters per minute – lpm (0.05 to 1.5 gallons per minute – gpm). Over this range, the expanded uncertainty claim for this facility is ±0.01%, at 95% confidence level. The uncertainty of a dual-turbine meter tested in the system is also reported. In addition, NIST is working to incorporate additional piston provers so that the flow for hydrocarbon liquids calibration service will reach 760 lpm (200 gpm).Copyright

Error Free Liquid Flow Diverters for Calibration Facilities

A design for diverter valves in gravimetric liquid flow calibration facilities is proposed. The concept makes use of repeated unidirectional motions of the diverter valve to reduce errors associated with asymmetry in the diverter valve motion and in the liquid jet velocity profile. Various implementation examples are provided and their benefits are discussed.Copyright