Deliverable D4 (A2.4.4) Technical report on the inter-comparison of sonic nozzles (CFVNs) of different sizes, shapes, and surface roughness, using alternative fluids (based on e.g. Reynolds number equivalence) with focus on discharge coefficient. The report will also explain their high-pressure calibration behaviour (pmax = 100 MPa) and possible differences in their behaviour compared with the ISO curves from ISO 9300

This report was written as part of activity A2.4.4 from the EMPIR Metrology infrastructure for high-pressure gas and liquified hydrogen flows (MetHyInfra) project. The three-year European project commenced on 1st June 2021 and focused on providing metrological infrastructure and traceability for high pressure hydrogen flow meter calibration (1000 bar / 3.6 kg/min), fuel cells applications (4 kg/h, 30 bar) and liquid hydrogen. For more details about this project please visit methyinfra.ptb.de.
The purpose of this document is to document an inter-comparison of sonic nozzles (CFVNs) of different sizes, shapes, and surface roughness, using alternative fluids (based on Reynolds number equivalence) with a focus on discharge coefficient (Cd). The report also explains their high-pressure calibration behaviour (p_max = 100 MPa) and difference in their behaviour compared with the ISO curves from ISO 9300:2022.