FLEXIM collaborates with the PTB (Physikalisch-Technische Bundesanstalt – Physical Technical Federal Institution) as part of a research project on the exact determination of flow profiles and their influence on the measuring accuracy of clamp-on ultrasonic flowmeters.
The PTB is Germany’s national metrology institute. Measuring with the highest accuracy and reliability is their core competence.
FLEXIM sees itself as a technology leader in the field of non-invasive flow measurement with ultrasound. In order to extend this lead, FLEXIM is collaborating with PTB within the framework of a research project. At its historic location in Berlin’s Charlottenburg district, PTB has a standard flow rate testing system manufactured with the highest precision possible on its heat meter test track. 25 metre straight pipe lengths with nominal widths from DN 80 to DN 400 ensure the best flow and measuring conditions.
The accuracy of the non-invasive flow measurement depends essentially on the flow profile. If this is undisturbed – as on the PTB test bench –the clamp-on ultrasonic flowmeters measure with the utmost accuracy. In practice, however, there are not always sufficiently large inlet lengths to be able to assume an undisturbed flow profile.
The research collaboration with PTB therefore focuses on precise measurement and subsequent mathematical-numerical modelling of disturbed flow profiles. For this purpose, precisely defined disturbed flow conditions are generated in the flow measuring stand and measured by means of highly accurate laser-optical systems (Laser Doppler Velocimetry and Particle Image Velocimetry) over the flow cross-section. In a second step, the flow rates at the location of the flow profile determination are each recorded with several FLUXUS clamp-on ultrasonic flowmeters from FLEXIM. Evaluation of the flow profile disturbances determined with the Laser Doppler Velocimetry systems allows the development of even better models for a numerical flow profile correction and thus creates the basis for a higher accuracy of the FLUXUS ultrasonic flowmeters even under difficult flow conditions.