Design and application of digital valve in gas supply control system for wind tunnel

As the required indicators of air supply experiments in the wind tunnel become more rigorous, the analog control valve is unable to meet the demands. Considering the drawback of PCM digital valve and PWM digital valve, the PCM+PWM digital valve is put forward to meet the gas supply requirements, where the PWM digital valve regulates the flow under the benchmark which is provided by the PCM digital valve. The research status and design index of the digital valve, the selection and design of the nozzle, the distribution of the throat area, the calculation and selection of the magnetic valve, and the flow control method based on PID are introduced in detail. By repeated debugging, parameters optimizing and performance testing, several gas supply experiments are conducted. Experimental results show that the application of the digital valve is successful, the measuring accuracy of the mass flow control is superior to ±3g/s, and the characteristics of fast response, large range, and high reliability are achieved to provide strong support for gas supply experiments.