Research On The Flow Process And Flow Characteristics Of Nitrous Oxide Injectors

The liquid nitrous oxide supply system was designed based on the application of nitrous oxide engine. Flow characteristics of pipeline and the nitrous oxide spray state were especially analyzed. Nine different injectors were designed, which are used in nitrous oxide/toluene bi-propellant engines, and flow characteristics are researched through cold experiments with high/normal back pressure.Liquid nitrous oxide injection experiments indicate that nitrous oxide flows in two-phase flow type and injects in two-phase flow type. Many problems such as measurement of two-phase flow, judgement of flow state in pipeline and safety in operation were solved successfully.Theroy model was choosed from two different two-phase models, homogeneous flow model and separating flow model. Finally the second one was considered to be the best by comparing with the cold flow tests. The concepts of the phase area ratio and critical gas/liquid ratio are put forward based on the model. Pressure characteristics of mixing cavity was analyzed and found that it is more sensitive to gaseous medium. Different injectors'discharge coefficients were studied by changing the recess length, exit length of outlet, size of the annulus, and other geometry parameters. Comparing experiment results under different back pressures, it is found that back pressure does not affect corresponding laws between the geometry parameters and discharge coefficient. When the back pressure rises, discharge coefficient becomes larger. By summarizing the research on injectors, design method of nitrous oxide injector is advanced.