Transient Fluid Flow in Short-Pulse Operation of Bipropellant Thrusters

Abstract

The flow of propellants into an evacuated injector during a short pulse was measured for several propellants using two different methods. In the first method, the fluid front was observed with a high-speed camera. In the second method, the average fluid velocity during a pulse was determined from the pressure rise in the chamber from a pulse. The propellants tested were hydrazine, monomethyl hydrazine, hexane, water, and nitrogen tetroxide. The measured velocities are an order of magnitude slower than the steady-state velocities under the same conditions. The results are consistent with the development of a flow controlled by inertia and viscous drag. The implications for pulsed operation of bipropellant thrusters are discussed.