Experimental Study on The Flow Process and Flow Characteristics of a Bubble Atomizing Injector Using Nitrous Oxide

摘要

A kind of injector using the propellant nitrous oxide and toluene was designed andexperimentally investigated in this paper, while the actuating medium streamed through the ring-split andcircular hole respectively. Due to the nitrous oxide's property of easy boiloff, experiments were carried outwith air-water two-phase flow replacing nitrous oxide. The main focus is on the discharge characteristic oftwo-phase flow flowing in the ring-split. Experiments for two-phase flow conditions covered the air-to-liquidmass flow rate ratio (X_x) range of 0.01-0.2. The research indicated that the stratified-flow model was bettersuited to depicting and explaining the injectors' flow characteristics than the mixed-flow model, because themass flow coefficient calculated by the former is almost completely depend on X_x. It was also found that, bymany repetitive experiments, there was a critical value of air-to-liquid mass flow rate ratio (X_(cr)) which makesthe corresponding mass flow coefficient achieving minimal value about 0.03. Analyzing the data the authorconcluded X=X_(cr) was possibly the turning point from the bubble flow pattern to the slug pattern within theinjector. The author also validated the conclusion by studying the upstream pressure fluctuation of theinjector.