INRIM has been developed a LDA calibrator for a speed range between 0.03 m/s and 14 m/s. The device is composed by a rotating disk with a surface manufactured that simulates the tracer particles. The device is also composed by an alignment system to adapt the calibrator to different focal lengths and beam angles. The particularity of this prototype consists in its solidity and portability. Actually, the target of this device is not the improvement of the general measurement accuracy for LDA calibrators but it has been designed to be portable in order to be used as a possible transfer device...
A liquid flow standard system has been used to calibrate liquid volume at a specific flow rate. However, liquid flow rate has not been considered as a calibration item due to lack of flow diversion mechanism. To enable the liquid flow rate calibration service, uncertainty due to flow diversion was estimated. Diversion timing error as well as temperature dependence on the flow rate was considered. Uncertainty contributions by the two factors were largest more than 40 % of the total uncertainty. On the while, the uncertainty contributions due to other factors were less than 5 %.
This paper describes an accurate determination for the water thermal expansion coefficient starting from CIPM water density equation. This thermal expansion coefficient, as it is determined, is to be used in the volume determination according to the volumetric method.
Due to their long term stability, well understood flow behaviour and very low uncertainty, standard critical flow Venturi nozzles (CFVN) are enjoying great popularity as a calibration tool and flow metering device. Their application to very small flow rates beyond the ISO 9300 Standard, however, leaves many questions unanswered. The present work aimed at detailed description of flow fields within CFVNs of diameters between 15 µm and 80 µm. The present numerical flow simulations were validated by corresponding experimental work.
For the measurement of velocity of gas streams in ducts, the S pitot tube is one of the most widely used velocity measurement devices. Factors as Reynolds number and misalignment can be additional error sources for the S pitot coefficient. The variation of S pitot coefficient is observed on five different manufactures of S pitot through the airs peed standard system. The results of these experiments indicate that the coefficient curve of S pitot tube is fluctuated at small velocities around 0.2 % up to 0.7 %. The coefficient value of S pitot tube has a band from 2 % to 4 %
The feasibility of Lorentz Force Velocimetry for flow measurement of poorly conducting electrolytes is demonstrated using experimental results on salt water flow exposed to a permanent magnet system. The results provide a linear relationship between the measured Lorentz force and flow velocity, consistent with the theoretical scaling laws. Further measurements are currently being performed on a new experimental setup. The new experiments are aimed at investigating the effect of flow dynamics on the measured force.
A magnetic flowmeter is described in which the inductor is an electromagnet inducing a pulsed lowfrequency magnetic field in the pipe channel. Due to an alternating magnetic field applied, the effect of external noise caused by the power-line frequency is fully excluded, the effect of thermo-electromotive force is significantly reduced, and the effect of eddy currents is practically excluded, etc.
In the present investigation, the problem of accurate determination of volumetric flows by means of vortex-shedding flow meters in the case of upstream disturbances produced by bends has been studied. To this end, the corresponding flow field was investigated experimentally and by detailed numerical simulation for the case of incompressible fluid flow (water). The computations were carried out for a limited number of cases using the three-dimensional unsteady incompressible solver of the Navier-Stokes equations as included in the adapco Star CCM+ commercial program.. The effects of...
A novel method of measuring the annular concentric clearance is proposed to estimate the clearance height between the piston and the cylinder. The principle of the method is that pneumatic flow rate through the clearance is an assured function of the height and the upper stream pressure of clearance. Firstly, the measuring principle was proposed. Then the simulation model was built in AMESim, and the clearance-pressure data tables were obtained. Finally, the experiment was carried out, and the results showed that the clearance measuring method was effective and can be used to estimate...
The dynamic method of generating reference Volatile Organic Compounds (VOC) mixtures at trace level requires the uninterrupted blending of the component flows. The accurate control of the dilution air flows can be realized by Mass Flow Controllers (MFC). Accuracy and stability of MFC are here measured and discussed in order to verify their use in dynamic gas dilutors. Long term stability confirm the necessity of calibrating MFC before each use. MFC accuracy results not pressure drop dependent, but limited by the short term stability for flows below than 70% of MFC full scale and generation...