Sonic nozzles ; CFD ; Wall roughness ; Heat transfer ; Turbulence intensity
Zusammenfassung
Sonic nozzles depict a well-established standard for the precise measurement of gas flows in various engineering and metrological applications. During each nozzle calibration, numerous factors, including nozzle shape, wall roughness, wall heat transfer, and real gas effects, influence the characteristics of the nozzle. These factors are often not measured or accounted for in experimental campaigns but can considerably affect the development of the boundary layer within the nozzle throat and the thermodynamic properties of the considered gas and thus the prediction of the mass flow rate. This numerical study investigates the effects of different nozzle shapes, roughness values, wall temperatures, and gas models on the flow in sonic nozzles not only individually but also in interaction with each other by using computational fluid dynamics. Deviations in the nozzle shape reveal an impact on the discharge coefficient in both the laminar and turbulent range. The discharge coefficient decreases in the turbulent range with increasing roughness values. The wall heat transfer primarily affects the flow in the laminar range, where the mass flow rate is the highest for colder walls. Real gas effects become increasingly relevant at pressures above 40 bar for hydrogen gas. A variational study combining these factors demonstrates that the superposition of flow results of individual variations serves as an appropriate first approximation for those of combined variations. Overall, this numerical work provides a deeper insight into how relevant factors of nozzle calibration and combinations of those affect the mass flow rate in sonic nozzles.
Themenbereich der Metrologie
Metrologie in der Medizin
Förderinformationen (1)
Förderername: European Metrology Programme for Innovation and Research
Förderinformationen (2)
Förderername: Horizon 2020 Framework Programme
Förderinformationen (3)
Förderername: EURAMET European Metrology Programme for Innovation and Research
Zitierung
Weiss, S., Mickan, B., Polansky, J., Mohammadkhani, A., Oberleithner, K., Bär, M., & Schmelter, S. (2026). Numerical investigation of individual and combined flow effects and influences in sonic nozzles. Measurement, 260, 119826-1–119826-13. https://doi.org/10.1016/j.measurement.2025.119826
