Research On Continuous Throttling Technology Of Gas Generating

The key technologies of the throttleable gas generator, including mass flow rate throttling of propellants, throttling injector and continuous throttling of gas generating were studied through theoretical, numerical and experimental method. Moreover, the throttleable technology was demonstrated by experiment. Characteristic of flux throttling was obtained and then an investigation of the atomization process of coaxial injector and combustion process of the throttleable gas generator was carried out. All the investigation provides references for continuous throttling technology of gas generating.A throttleable critical sonic nozzle(TSN) and a throttleable cavitation ventrui nozzle(TVN) were built based on the critical theory and cavitation theory to throttle the mass flow rate of oxygen and kerosene respectively. In order to achieve a linear flow rate profile, a special plug contour was designed based on the envelope theory. The inner flow and flow characteristic of the TSN and TVN were investigated through numerical simulation, as a reference for the later research. The characteristic of the TSN and TVN was examined by using air and water as propellant simulants. Special attention was given to the static characteristic including linearity, repeatability and hysteresis. The result showed that their performed well. Experiment was employed to investigate the dynamic characteristic. It was found that when throttled slower than 3.107kg?s-2 for the TSN and 11.95kg?s-2 for the TVN, the throttling process could be treated as quasi static condition. Another conclusion about the TSN and TVN was that the influence of the boundary layer to the discharge coefficient was notable. The discharge coefficient vs. the hydraulic diameter in the throat fitted to the power law wel.Swirl-coaxial injectors was designed and tested. Water and air were employed as the liquid and gaseous propellants simulants respectively. The injector responses quickly and stably, and the discharge coefficient is independent of throttling rate. Then, the dynamic spatial configuration of the spray was captured by high speed camera. The spray angle was obtained from the image. It was found that the spray angle increase when mass flow rate increased. Later, the malvern device measured the diameters of particles when the mass flow rate was throttling. Malvern data shows that SMD responses quickly and decreased when mass flow rate increased. Moreover, the SMD in different position share the same trends of variation. The atomization process under throttling rate in current experiment could be treated as quasi static condition.The throttleable gas generator is comprised of d ual- manifold injectors(swirl coaxial injector) and supply system which including the TSN&TVN. Firing tests were carried out with oxygen and kerosene occupied as propellants. Mix ratio was adjusted through two ways, one is changing the kerosene mass flow rate and keep oxygen mass flow rate, another is changing oxygen mass flow rate and keep kerosene mass flow rate. Results showed that the throttleable gas generator worked stable and responded quickly. The previous way influenced the chamber pressure little, while the later way had a great influence on the chamber pressure. The kerosene droplet did not finish the evaporation process inside the chamber. Two ways effect the flame structure different, the inc rease of oxygen result in outer flame staying around the injector and may lead to injector damage. Combustion efficiency and c*(characteristic velocity) increase linearly with mixing ratio when mixing ratio less than 0.22. When mixing ratio exceed s 0.54, it is hard to improve the combustion efficiency and c*.