Switched nozzle valve

A method of regulating gas flow for an application requiring a regulated gas flow rate using a switched nozzle valve, the method comprising:

• flowing the gas through the switched nozzle valve, the switched nozzle valve having a converging section, a nozzle throat, a valve element, a valve seat, and a diverging section having an exit to be in fluid communication with an application requiring gas flow control, the valve element being seatable on the valve seat;
• switching the valve by an operator at a switching frequency using a pulse-width-modulation (PWM) signal generated by a microprocessor between a fully closed position where the valve element is seated on the valve seat and a fully open position where the valve element is spaced from the valve seat and the nozzle throat is unimpeded to achieve a velocity and a time-averaged flow rate of the gas without a feedback measurement;
• accelerating the gas in the converging section such that the velocity of the gas reaches the speed of sound such that the flow in the orifice is in a choked condition, wherein the pressure in the orifice is at a critical pressure;
• further accelerating the gas in a first part of the diverging section;
• forming a shock wave at the diverging section;
• abruptly decelerating the gas by the shock wave;
• and
• further decelerating the gas by a remaining portion of the diverging section downstream of the shock wave for recovering pressure loss while maintaining the speed of sound of the gas in the orifice, thereby providing gas control to the application.