In the monitoring of greenhouse gas emission from industrial smoke-stacks, the most common device used to measure the stack gas velocity is the S-type Pitot tube in South Korea, which is used to estimate the volumetric flow rate by what is termed the Continuous Emission Monitoring System (CEMS). The S-type Pitot tube installed in the stack is inevitably affected during velocity measurements by velocity changes, yaw and pitch angle misalignments due to the harsh environments. Various geometries of the S-type Pitot tube can affect the characteristics of the S-type Pitot tube coefficients, including the degree of sensitivity to velocity changes and yaw and pitch yaw angle misalignments. Nevertheless, there are no detailed guidelines pertaining to the S-type Pitot tube geometry considering accurate and reliable measurements in the ISO, EPA and ASTM international standards. In the present study, S-type Pitot tubes with various geometric parameters, in this case the distance between the impact and wake orifices and the bending angle of the orifices, were manufactured by a 3D printer. Wind tunnel experiments were conducted in the Korea Research Institute of Standards and Science (KRISS) air speed standard system to determine the optimal geometry of an S-type Pitot tube for the accuracy velocity measurements in actual smokestacks which undergo velocity changes and yaw and pitch angle misalignments. Particle image velocimetry was also used to understand the flow phenomena around an S-type Pitot tube under various geometric and misalignment conditions by means of qualitative visualization.

Radiopharmaceuticals used in nuclear medicine for therapy or diagnosis (molecular imaging, PETscan, scintigraphy) are characterized in terms of volume activity before injection to patients. The current measurement process relies on dose calibrators which have to be calibrated by transfer standards, traceable to primary standards. For very short half-life radionuclides (few minutes), the metrological traceability can only be assured through an on-site calibration with primary standards. However, until now, there is no primary system for the direct measurement of such high activity radioactive solutions. This study presents the subsystem under development for the measurement of a sampled volume of the order of one microliter with an associated relative target standard uncertainty of 1 %.
This article focuses on the volume measurement method development and its validation by comparison to the gravimetric method.
The paper, in a first part, describes the developed method and the associated hardware and software. The authors have chosen a non-contact optical method implemented by a microscope camera and associated optics in front of a transparent capillary.
The second part of the paper describes the measurement process. Several image processing steps are described and the traceability to dimensional units are presented.
Finally, the paper presents some validation results by comparison to a gravimetric measurement, including repeatability and accuracy tests. Further development and improvements, necessary for the finalization of the prototype and the measurement of nano-flow rates are discussed.

Pitot tube has the advantages of small pressure loss, cost economical, compact size, easy to cary, install and measure., which make It suitable for the flow measurement of medium and large d ameter pipes, and flow velocity and velocity distribution measurement at any point in air duct, water pipe and mine. However, when measuring the mixed phase fluid of gas and liquid, the pitot tube will have abnormal fluctuations in the flow measurement with the passage of time, and the measurement result would be far from the actual flow rate.
Gas-liquid mixed phase fluid is widely used in industrial production. Because gas phase fluid can be compressed, and there is shifting between gas and liquid phases, and the two-phase interface is complex and variable, the flow measurement of gas-liquid mixed phase flow is very difficult . In actual measurement, there could be condense liquid slowly formed on the inner wall of the pressure tapping hole of the pitot tube. As the amount of the condense water increase, due to the effect of liquid surface tension. attracted by internal molecules, the liquid surface molecules have a tendency to be pulled inside. As time goes by, there will be more and more water drops, and once it reached to a certain amount, the water drops will form a water film. Once the water film is formed, the pressure tapping hole of the pitot tube is divided into the meas ring side and the actual flow side by the water film, and the measuring side cannot correctly respond to the change of the flow rate any more, and therefore cause inaccurate measurement.
Based on the analysis of the feature of the flow profile of gas-liquid mixed-phase fluid and the data of the forming of water film, we propose a method of recognizing the abnormal data caused by the water fluid in a gas-liquid mixed-phase fluid base on the square error algorithm. We add a two-way solenoid valve to the front and rear pressure holes of the pitot tube. Under normal circumstances, the solenoid valve is closed. Once the algorithm recognizes the abnormal data, it opens the pressure-receiving hole by controlling the small solenoid valve built in the pitot tube, and the positive pressure or negative pressure of the gas-liquid mixed phase flow destroys the formation of the water film.

An air test line of 50mm diameter was used in experiments covering two kinds of straight pipe length, and the numerical simulation results of vortex shedding frequency, which originated from the ANSYS FLUENT analysis results, were proved to be highly consistent with the experimental results. Based on this comparison, flow field simulation studies, including 13 pipe conditions, were carried out to establish the effect of upstream and downstream elbow fittings on the performance of the vortex flowmeter. The results indicated that the influences of the upstream straight pipe length were more obvious than the downstream straight pipe length. When there was an upstream elbow, the frequency value was greatly reduced, and the maximum error was -60.62%. The closer the elbow was to the vortex generator, the larger the decrease. The downstream elbows had a relatively small influence on the measurement results, and the maximum error was -13.23%. Considering the asymmetry of the 2D pipeline, the 3D simulations of part of the pipeline condition were further executed. The differences between 2D and 3D calculation results were analyzed, and the application value of different simulation results was explored.

For the butterfly flow-regulating valve commonly used in the variable head flow standard device, the threedimensional flow field in the valve body was simulated during the flow regulating process by CFD dynamic mesh technology. The flow field changes with cloud maps in the internal and downstream piping of the valve body under several operating conditions of 10°, 30°, 45°, 60°and 90°opening was proposed in the condition of constant water head. The simulation results also show that there are two opposite vortices in the flow field downstream of the valve body at 10° and 30° opening, and the valve opening has a nonlinear function relationship with the flow. Meanwhile, The flow control function of butterfly valve was presented to keep the flowrate constant under variable head conditions. Experiments were carried out on a variable head simulation device with an effective head of 3m and a pipe diameter of 150mm. Experiments show that the control function can be used to open-loop control the butterfly valve, and the control accuracy of flow fluctuation less than 1% can be obtained.