For traceability of the new glycol test-bench for flow meters at IAV GmbH in Gifhorn LDV measurements were realized.
Water-glycol-mixture is an often used medium in the automotive field as a coolant. Under operating conditions the fluid is exposed to large variation of temperature. Classical flowmeters (such as magnetic flow sensors) for mass and volume flow have to be calibrated periodically on a special test bench to provide accurate measurement-results.
The special type of medium and large temperature-variations for example -20°C to +125°C make the traceability of the test-bench to a challenging task.
Conventional control standards for mass/volume flow such as weighing devices or test containers are not an appropriate solution for this kind of test-bench. Therefore a Coriolis mass-flowmeter was used as a master-standard which was checked and calibrated with the LDV-measurement.
The goal of this measurement was to figure out the real volume flow passing through the pipes. Therefore it was important to take measurements of the local axial velocities of the cross section with a high resolution. The volume flow is calculated by integration of the local velocities over the cross-section. To converge to the real value of the volume flow the measuring uncertainty has to be kept as small as possible.
The measurement revealed a clearer picture of the flow conditions for each operating point. The flow conditions were assessed by the well established guideline for fluid dynamic validation of calibration test-benches acc. to EN 1434.