Instability characters and suppression method of a pressure regulator

Abstract

With the increasing interest in hypersonic propulsion, National University of Defense Technology in China sets up a large high-temperature wind tunnel. A pilot-operated pressure regulator is developed to supply gas with a given pressure to the wind tunnel. Although the regulator works normally and stably during the working stage, severe oscillations with maximum amplitude of 3 MPa occur during the pressurization stage. To solve the problem, a numerical approach is developed to model the supply system, especially the pressure regulator. The approach is validated by comparing numerical results with experimental results. It turns out that the frequency of the oscillation is mainly determined by the inlet pipe, while the amplitude is affected by the downstream volume, the seal chamber and the seal orifice. To suppress the instability, a connecting pipe is adopted to let the gas in the seal chamber come from outside of the regulator. The method is quite simple but the effect is dramatic, as is attested feasible by both simulations and experiments.