Simulation of the Outflow of Supersonic Jets into a Rarefied Medium in Pulse Modes

The use of electromagnetic valves for generating pulsed flow modes of a high-density supersonic jet in the second and submillisecond ranges is analyzed. It has been shown that “slow” second-range valves do not allow achieving a quasi-stationary mode with a high gas flow rate compared to a stationary outflow; submillisecond-range “fast” valves generate gas pulses with parameters necessary to simulate high-flow conditions at background gas pressures that do not overload the high-vacuum pumping system. It is found that the submillisecond valve provides the ability to simulate instantaneous flow rates of up to several tens of grams of a product per second in a pulse at pressures in the prechamber of up to 2 MPa and a pressure in the surrounding space of 1–3 Pa. A set of sonic and supersonic nozzles has been implemented with an electromagnetic valve device and power-supply and control systems that provide the gas outflow from the nozzle prechamber during a controlled period of time from 0.3 to 1.5 ms with a given duty cycle varying from several tens to thousands. The generated gas pulses have a trapezoidal shape with a quasi-stationary core.