[en] The gage utilizes the differential pressure given by a differential pressure producer to generate, in a bypass, a partial gas flow measured by means of a direct-reading anemometer of windmill type. The partial gas flow is generated between pressure pick-up openings in the gas-suction pipe in front of a venturi insert and pressure pick-up openings at the bottleneck of the venturi insert. The reading of the anemometer is proportional to the main gas flow and independent of the variables of state and the properties of the gases to be measured. (RW)

[en] Radioactive tracers have been used for the calibration of a Venturi type flowmeter. This instrument is usually applied for the measurement of volumetric flow. The curve of calibration that was obtained is represented by the equation Q=113,7(ΔH)sup(0,535). Here Q is the volumetric flow in cm³/s and ΔH is the pressure difference in mm Hg as indicated by the Venturi type flowmeter. An incertainty of 2% has been estimated for any measurement in the context of this experiment. The results obtained are in harmony with previous measurements

[en] The nuclear reactor described includes a pressure vessel and at least one inlet nozzle and one outlet nozzle and pipes connected to these nozzles for circulating a coolant in the vessel to remove the heat generated by the fuel rods. A flow rate restrictor is fitted in each inlet nozzle and is designed to put up a relatively weak resistance to the direct flow of the coolant entering the vessel and a highly increased resistance to any coolant flowing in the opposite direction, so as to limit the coolant counterflow as from the vessel further to a significant burst in the coolant intake pipe. The flow rate restrictor is made up of a certain number of appreciably parallel venturi channels and extending longitudinally from the inlet nozzle so that their resistance to the direct flow of coolant entering the vessel is distinctly less than their resistance to the flow in the opposite direction. It is composed of a moulded part entirely located inside the inlet nozzle so that there is no risk of it being damaged in the event of a burst occurring in the inlet pipe

[en] Controlling the containment pressure is an important part of the Swedish severe accident mitigation strategy. As a final measure, venting of the containment atmosphere to the environment is feasible via a filtered venting system using a water scrubber as the filtering device. The comprehensive theoretical and experimental verification of the Multi Venturi Scrubber System has resulted in the following predicted scrubber performance: Both during the scrubber heat-up phase and in long periods of operation, where the water of the scrubber is heated to saturation, a decontamination factor of the order of several thousand is predicted. During no conditions foreseen in the safety analysis are decontamination factors below DF = 500 in the BWR scrubber and DF = 1500 in the PWR scrubber envisaged. These values are equivalent to a retention of 99.8 % and 99.9 % respectively and correspond to a case with only about 10-20 cm of water above the venturi tube outlets and unfavorable gas dynamic conditions. They can be compared to the design values (DF = 100 and 500, respectively) required to limit ground contamination to the very low level specified by Swedish authorities. 1 fig

[en] An experimental investigation was undertaken to determine those scaling parameters applicable to measuring the mass flow rate of gas-particle suspensions through venturis. It was found that Stokes number and the particle/gas loading ratio are the two most important parameters. The results show that pressure drop increases linearly with loading ratio and decreases monotonically with increasing Stokes number. The results also indicate that *b-ratio and orientation of venturi do not significantly affect the pressure drop. Data for irregularly shaped pulverized coal particles show higher pressure drop compared with those for spherical particles. A quasi one-dimensional numerical model overpredicts the pressure drop, but a two-dimensional model demonstrates improved agreement. (Author)

[en] The present paper discusses the use of venturi flow meters for measurement of vapor quality of helium two-phase flow. Tests were performed by connecting two identical venturis with 2.29 mm throat and 4.57 mm inlet diameters in series with a vertical two-phase helium flow loop. With one venturi operating in liquid and the second one operating in two-phase regime as controlled by an inline heater, the ratio of the pressure drop across the two venturis is found to be well correlated to the vapor quality of the two-phase flow. Data presented are for vertical upflow of two-phase helium at 4.2 K with vapor quality between zero and 100% under both forced flow and natural circulating flow conditions. The forced flow rates, controlled by a flexible bellows acting as a positive displacement pump, range from 1.0 g/s up to 2.5 g/s. Within the parameter range covered in this test, the result can be well described by the homogeneous model

[en] A computational fluid dynamics analysis is conducted to evaluate the prediction performance of the standard and RNG κ e - eddy viscosity models, and differential stress model (DSM). A 5x5 rod array with the split vane is simulated and the numerical predictions are compared with the experimental results where applicable. The curvature-compensated convective transport (CCCT) scheme is used to discretise the convection term. There is a negligible difference in the prediction performance between the standard and RNG κ e - models. DSM was found to more accurately predict characteristics of turbulent flow in the fuel bundle with the flow-deflecting vane

[en] Current feeder system (CFS) of steady state superconducting tokamak 1 (SST-1) consists of ten pair of vapour cooled current leads (VCCL). Helium vapour consumption of a VCCL is an important parameter to be measured accurately during operation of current leads. To measure flow precisely and accurately, we use venturi type flow element. A venturi flow element was designed for required flow rate with accuracy of approximately +/- 1% and the same was machined, finally it was calibrated and validated to define its discharge co efficient and found to be in agreement with the designed value. These venturi flow elements with Differential pressure transmitter (DPT) have been installed in helium gas return network of current feeder system of SST-1. This paper describes design, validation and installation and commissioning of venturi flow element with its DPT. (author)

[en] Highlights: • Venturi erosion characteristics is discovered based on big data. • The multi-level evaluation method of venturi is proposed. • The accurate correction method of venturi is proposed. • The replacement criterion is defined from the principle of venturi. The main feed water flow for nuclear power units is measured by Venturi tubes. These use the principle of differential pressure to act as throttling devices. Over the course of their operational life, the passage of medium- and high-speed fluids can erode Venturi tubes, undermining the measurement accuracy of the differential pressure and flow. Venturi tubes play a vital role in nuclear power units, participating in the regulation of the water level in steam generator control systems and protecting reactor signals. Thus, the accuracy of their signal measurements directly affects the safe and stable operation of nuclear power units. This paper analyzes statistical data regarding the main feed water flow measurements from 26 nuclear power units. Combined with the working principles of Venturi tubes, it establishes the mechanism governing erosion in Venturi tubes and its characteristics over long-term operation. A multi-level assessment method for Venturi tube erosion then is proposed that can evaluate the accuracy of flow measurements in terms of degradation, failure and replacement. On the basis of this method, accurate corrections of the differential pressure can be implemented or the tubes replaced. The method was applied in nuclear power units and its effectiveness verified. It can therefore provide a reliable basis for improvements in the safety of nuclear power unit operation and serve as a reference for other chemical and thermal power fields where Venturi tubes are used for measurement and regulation.

[en] In order to study the effect of the diffusion angle on the turbulence in the venturi tube, in this work, the stereo-particle image velocimetry is used to measure the transient velocity of the diffusion part of venturi tube, which diffusion angle is 10°, 12.5°, 15° and 20°, respectively, and the time-averaged velocity is obtained. Based on the transient velocity of the diffusion part of the venturi tube, the distribution of turbulent kinetic energy in the diffusion section is obtained by statistical analysis of the instantaneous velocity field. It is shown that the average velocity in the diffusion section of the venturi tubes of different structures presented an axisymmetric single peak distribution in the direction of the section diameter, and the turbulent kinetic energy presented an axisymmetric double peak distribution in the section diameter. Flow separation can be observed in all experimental condition. With the increasing of the diffusion angle, the largest turbulent kinetic energy increases, but the radial width of the main flow zone does not change, and the radial width of the separation flow zone increases, but the effect on the proportion of the separation flow zone is small, and the high turbulent kinetic energy zone widens. With the increasing of Reynolds number, the peak value of turbulent kinetic energy increases, which is mainly caused by the axial Reynolds stress, and the proportion of separated flow area decreased slightly, but the distribution of main flow area and separated flow area changes little. This study provides an experimental basis for studying the flow field of the venturi tube with high Reynolds number at different angles. (authors)