1 Influence of Reynolds number
1) Influence of Reynolds number. From the working principle of the vortex flowmeter and the relationship between the Strouhal number and Reynolds number curve in Fig. 4, we can know that the range of Reynolds number is 2×104～7×106, which is the normal working range of the instrument. Although the Reynolds number is in the range of 5×103 to 2×104, it is also within the working range of the instrument. However, because the Strouhal number increases, measurement errors will occur, and the flow coefficient must be corrected to ensure the flow measurement accuracy.
2) Correction of Reynolds number effects. Reynolds number corrections generally have two methods. One is accomplished in the flow quadratic table and is applicable to a vortex flowmeter itself which has no correction capability. The other is implemented in a vortex flow sensor (transmitter) and is applicable to a vortex flowmeter that has a calibration capability.
2 Effect of fluid temperature changes
1) The effect of fluid temperature changes. From the working principle of the vortex flowmeter and formula (3) we can see that the flow coefficient K of the vortex flowmeter is affected by the temperature of the fluid and consists of two parts: a. caused by the change in the width d of the generated body; b. D caused by changes.
From the formula (1), it can be seen that f is inversely proportional to d, and K is inversely proportional to D2. Since the fluid temperature used in practice is significantly different from the design fluid temperature, the introduced error is considerable. 2) Correction of the effects of fluid temperature changes. The correction method for the effect of fluid temperature changes is to recalculate the flow coefficient according to the actual temperature of the fluid.
3 Impact of body flow heading
1) The impact of the build-up of the influx on the body. In the fluid to be measured, if there are viscous granules or fibrous substances with more inclusions, they will gradually accumulate on the flow-in surface of the vortex generator, causing changes in its geometry and dimensions. As a result, the flow coefficient will change accordingly, resulting in errors. .
2) The processing of the accumulation of the inflow surface of the body occurs. There is no good way to correct the impact of the build-up of body-facing flow surfaces. If necessary, it can be solved by periodically changing the body.
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