Development of a high-capacity multi-nozzle gas flow standard facility

To meet the calibration requirements of the flow meter used in the FL-9 Low-speed Pressurized Wind Tunnel inlet test at the Aviation Industry Corporation of China (AVIC) Aerodynamics Research Institute, with a maximum flow rate of 45 kg/s, this paper presents the development of a large-scale multi-critical flow Venturi nozzle gas flow standard device. Baded on the measurement principle of critical flow Venturi nozzles, the device innovatively proposes a six-bit binary combination critical flow Venturi nozzle gas flow standard scheme. Considering both development costs and the traceability limitations of individual nozzle dimensions, a design incorporating 10 larger throat diameter nozzles was adopted.In cases where the domestic primary standard range could not meet the traceability requirements, a secondary traceability transfer was ensured using small-scale critical flow Venturi nozzle secondary standards,thereby guaranteeing the tranceability and accuracy of the measurement values. The device operates at pressures from 0.1 MPa to 0.4 MPa, with a flow calibration range of 0.1855 kg/s to 46.7538 kg/s and a flow control resolution of 0.1855 kg/s to 0.7421 kg/s. Calibration results indicate that the expanded uncertainty of the flow measurement is 0.36%, meeting the calibration accuracy requirements for the pressurized inlet test flow meter.