Min Son

Ignition Transition by Ignition Position and Time of Gaseous Oxygen/Kerosene Combustor

The objective of this paper is to observe effects of an ignition position and time on the ignition transition. A gaseous oxygen and liquid kerosene are used for propellants with the shear-coaxial injector. In order to study the ignition delay time and combustion instability intensity, the pressure transducer was used. The ignition position was changed with the injector spacer. Sequences except the igniter operation time were fixed to compare the ignition time only. Initial pressure peak and ignition delay time increased as the ignition time was delayed. Also, the unstable flame development zone was detected as the igniter was away from the injector.

Macroscopic Analysis on Supercritical Transition of Liquid Hydrocarbon Fuel

In order to analyze supercritical transition of liquid hydrocarbon fuel which used propulsion engine, visualization of phase changing using Methylcyclohexane (MCH) was performed. Also, measurements of temperature and pressure were conducted to obtain saturation lines of MCH and Decane. delayed increase of the pressure existed near the critical point due to dramatical increase of specific heats and the critical opalescence was only observed from the end point of delaying to the critical point. Beyond the critical point, the boundary between phases disappeared and the strong density gradient was observed. As the comparison between experimental and numerical saturation lines, the numerical estimation for mixture had relatively little difference while the results of pure components had almost coincidence.

Visualizations of Gas-centered Swirl Sprays in Sub to Super Critical Conditions

ABSTRACT The gas-centerd swirl injectors are widely used on the main combustor of large liquid propellant rocket engines. Since the gas-liquid propellants, such as kerosene and oxygen-rich gas combination, are mixed and burned in the high pressure condition over the critic al pressure point, the cold-flow spray test in the atmospheric condition can not represent the actual spray pattern. To observe the near actual spray patterns of gas-centered swirl injector, the high pressure spray chamber and the control system were constructed. The operating sequence was controlled precisely to obtain clear visualization images.초 록 기체중심 스월 인젝터는 대형 액체 로켓 엔진의 주연소기로 광범위하게 사용되고 있다. 케로신과 산소과잉 가스와 같은 기체-액체 추진제들은 임계 압력 이상의 높은 압력 조건에서 혼합, 연소되므로 대기조건에서의 비연소 분무실험은 실제적인 분무 거동을 정확히 재현할 수 없다. 기체중심 스월 인젝터에서 실제 조건과 유사한 분무 패턴을 관측하기 위해서, 고압 챔버와 제어 시스템이 구성되었고 선명한 가시화 결과를 얻기 위하여 실험 과정이 정밀하게 제어되었다.Key Words: Gas-centered Swirl Injector(기체중심 스월 인젝터), Super Critical Spray(초임계 분무), Macroscopic Spray Pattern(거시적 분무 패턴)Received 10 December 2013 / Revised 7 May 2014 / Accepted 15 Ma y 2014

Visualization of Vortex Tube near Submerged Nozzle in Simulator of Solid Rocket Motor

A flow visualization near submerged nozzle of solid rocket motor was conducted by experiments. A numerical simulation was also performed to reveal detailed phenomena. Radial cold flow simulating hot gas was introduced by a porous grain model which was manufactured by perforated steel plates. The grain model was mounted in high-pressure chamber which has quartz glass at the top of the grain model. From the high-speed images, a rotating vortex was observed and the two type of counter-rotating momentums were generated in numerical results. The rotating momentum was generated at the fin-slot grain because of unbalance between high-velocity flow from slots and low-velocity flow from fin-bases. As a result, roll torques can be produced by the rotating vortex tube.