A NEW METHOD AND DEVICE FOR GAS FLOW-METER CALIBRATION ON AIR AT HIGH VELOCITIES |
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| M. D. Cazacu, R. M. R. Neacsu |
- Abstract:
- The work presents the theoretical and experimental research on a new method, more precise and more advantageous than the ones already known, for the gas flow-meter calibration on air for however high flow-rates or flow velocities and without pressure loss. The research also deals with a patented device, which can be attained under the best technical and economical conditions even for the largest sizes. This is why we have made both the method and the device available for all interested companies and metrological laboratories.
The theoretical research refers to the permanent, with axial symmetry flow of a compressible ideal or viscous fluid, in its isothermic or adiabatic evolution towards the entrance of a circular pipe.
The movement is obtained by the numerical integration of Euler or Navier-Stokes system of partial differential equations, completed with the equations of thermodynamic evolution tor compressible fluids. We introduce the stream function and eliminate the pressure and density functions with unknown values along the boundary of the domain occupied by the fluid.
From experimental point of view, the used method consists in the gas exhaustion out of a large enough chamber with the following known characteristics: absolute pressure, temperature and humidity of the air and its recycling through a pipe.
These characteristics have been stabilised after a certain time interval and measured with good accuracy. We have also measured the relative pressure inside the pipe whose diameter is constant and known, and on which the calibration flow-meter is mounted under admitted metrological conditions.
What follows is the measuring in the pipe-entrance region of the relative static pressure of exhausted gas, the velocity distribution being uniform in the rst section.
The device for the gas ow-meters calibration on air for large diameters and high velocities is made in entrance section, followed by an intermediary pipe section on which the calibration flow-meters are mounted, and at the end of this pipe there is an exhaustion blower with a valve at its outlet, for the adjustment of the exhausted flow-rate.
The greatest advantage of this method is that it can be applied under any atmosphericat conditions and that it is not necessary to ensure the rigorous temperature conditions (20 ± 0.5 °C), which are required in the metrological laboratories and which are standardly imposed but exemplary. The only requirement is the ensuring of a certain permanence of the working gas parameters, but only during each measurement session. - Keywords:
- flow-meter, gas flow-meter, flow-meter calibration, metrological calibration
- Download:
- IMEKO-TC9-2000-085.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC9
- Event name:
- FLOMEKO 2000
- Title:
- 10th Conference on Flow Measurement
- Place:
- Salvador, Bahia, BRAZIL
- Time:
- 04 June 2000 - 08 June 2000