Bodo Mickan, Rainer Kramer, Volker Strunck, Toralf Dietz
In Germany, a high pressure piston prover has been operated as the national volumetric primary standard for high-pressure natural gas for more than 15 years. The reliability and the claimed uncertainty of this system was proven in international key comparisons in which all relevant physical principles of traceability for gas measurements were assed. One important part of the uncertainty budget for the volume at the location of the meter under test (MuT) are dynamic effects caused by the limited dynamic in the transient response of the MuT in its indication of the flow. This impact of the...
Xiao-ming Sang, Li-fen Wan, Dong-jun Li, Hu Ji
This article introduces the detection method of the small throat diameter sonic nozzle by using a bell-type gas flow standard facility and its advantages. The related experiment researches have been done. It also describes the structure styles and the working principles. Meanwhile, it assesses the uncertainty of the outflow coefficient C for the small throat diameter sonic nozzle detected in this method. The feasibility of the detection method has been verified through the experiment data analysis.
Kyung-Am Park, Saeng-Hee Lee
The volumes of a storage tank and a temperature control loop of the high pressure gas flow standard system in KRISS were increased about three times to calibrate large flow meters and to test the flow capacity of control valves. Sonic nozzle bank consisted of 15 sonic nozzles (10, 13, and 19 mm diameters) is used as reference flow meter. The performance of this large air flow calibration system was evaluated.
Jiann-Lin Chen, Jhih-Wei Lin, Peng Chen, Chin-Yi Wie, Yu-Chung Huang
CFD technique has been used to simulate the flow field for a vortex flowmeter with different inflow conditions. The transient turbulent flows were simulated and the vortex shedding frequencies were obtained by FFT technique. The relation of Strouhal number versus Reynolds number with fully developed flow inlet was acquired numerically and experimentally for the standard case. The flow qualities along the piping were quantified by a specific definition. Several cases, including the asymmetric flows and unsteady sine-wave flows at the entrance, were studied and compared with the standard one....
B. H. Peng, J. J. Miau, F. Bao, L. D. Weng, C. C. Chao, C. C. Hsu
Flow-field study was conducted concerning vortex shedding from a circular cylinder with a slit. Experiments were carried out in a water channel and a low-speed wind tunnel with emphasis on the impact of the slit width on the quality of the vortex shedding signal measured. It is found that among the cases studied, whose slit widths ranging from 0 to 0.3 d , where d denotes the diameter of the circular cylinder, an optimal range of slit width, 0.1 - 0.15 d , was identified, in which not only the vortex shedding signals show the best quality, but also the relation of the Strouhal number against...
E. von Lavante, A. Gedikli, A. Thibaut, S. Tournillon, H. Krisch
The problem of accurate determination of volumetric flows by means of vortex-shedding flowmeters in the case of upstream disturbances caused by an butterfly valve, installed 5 diameters upstream of the meter, has been studied. To this end, the flow about the bluff body used in the presently studied vortex-shedding flow meter, having DN25 (simulation) and DN50 (experiments) test sections, was investigated experimentally and numerically.
Hui-Min Shen, Xin Fu
Due to the mechanism of vortex flowmeter, it is susceptible to the random disturbance from the ambient. With the goal of improving the poor sensitivity and noise immunity of conventional vortex flowmeter at low-flowrate, many researchers have done lots of work, focusing on innovation about the bluff, including the geometry or combinations, and the signal processing. This paper presents an adaptive algorithm for a vortex flowmeter with dual bluff body to improve its sensitivity for low flowrate applications. In our study, we get the distance where intension of vortex getting strongest by...
M. Akresh, L. Reindl, M. Vasic
It is known that a vortex signal is fundamentally related to the fluid flow velocity. When, a vortex flow meter operates at a low flow velocity, the vortex signal is weak, which has been discussed by several researchers in recent years. Subsequently, when a flow meter operates at a high flow velocity, the vortex signal is superimposed on additional signals, making it difficult to extract the true vortex signal. Both problems directly influence the measurement range of a vortex flow meter. The investigation of the vortex signal in high turbulent range is rarely mentioned in literature, and is...
Chih-Cheng Feng, Win-Ti Lin, Cheng-Tsair Yang
Center for Measurement Standards (CMS) developed a laminar flow element (LFE) type flow meter as a transfer standard. This LFE consists of a single straight glass capillary or multiple straight glass capillaries connected in parallel. Two gauges and one thermometer measured the inlet/outlet pressure and inlet temperature, respectively, and the differential pressure was restricted from 2 kPa to 100 kPa. The glass capillaries were manufactured by laser machining, resulting in consistent inner diameter and straight flow path. Characteristics of glass material also prevented the capillary from...
Unnikrishnan P. N., Sivaprakash K. G., S. Saseendran
A 2” NB Critical Flow Venturi Nozzle (CFVN) of Nominal Flow capacity 25 m³/h was designed at Fluid Control Research Institute (FCRI), India as a transfer standard for undertaking calibration of smaller capacity flow meters. The Nozzle fabricated was of Toroidal throat design and was assembled as per the general guidelines of ISO 9300:2005 "Measurement of gas flow by means of Critical flow Venturi nozzles". The Air Flow Measurement facilities at FCRI is equipped with Primary Standards Pressure-Volume-Temperature-time (PVTt) facility of 2 m³ Nominal volume and 90 m³/h maximum flow capacity and...