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기체주입식 분사기를 이용한 아음속 횡단류로 분사되는 이유체 혼합물의 분무특성
이근석 ( Keunseok Lee ),이원구 ( Wongu Lee ),안규복 ( Kyubok Ahn ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-
Spray characteristics of liquid and gas mixture ejected from effervescent injector to subsonic crossflow were experimentally studied. Effervescent injectors combined with aerator and plain orifice nozzle which had different ratio of the length to diameter (L/d = 10, 5) and operated with water and nitrogen. To analyze the breakup length and spray trajectory, instantaneous spray images according to GLR were obtained by high speed camera by injecting liquid and gas mixture into crossflow maintained at constant speed. Image analysis showed that as the GLR increased, the penetration height increased and the breakup length in the x direction decreased.
전단동축형 분사기의 유량계수에 대한 형상학적 변수들의 영향
안종현,이근석,안규복,Ahn, Jonghyeon,Lee, Keunseok,Ahn, Kyubok 한국분무공학회 2020 한국액체미립화학회지 Vol.25 No.3
Six shear coaxial injectors for a 3 tonf-class liquid rocket engine using oxygen and methane as propellants were designed and manufactured by considering geometric design parameters such as a recess length and a taper angle. Cold-flow tests on the injectors were performed using water and air as simulants. By changing the water mass flow rate and air mass flow rate, the injection pressure drop under single-injection and bi-injection was measured. The discharge coefficients through the injector oxidizer-side and fuel-side were calculated and the discharge coefficient ratio between bi-injection and single-injection was obtained. Under single-injection, the recess served to reduce the injection pressure drop on the injector fuel-side. For the injectors without recess, the discharge coefficients under bi-injection were almost the same as those under single-injection. However, for the injectors with recess, the taper angle and bi-injection had a significant effect on the discharge coefficient.
이원구(Wongu Lee),이근석(Keunseok Lee),안규복(Kyubok Ahn) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5
기체주입식 가변추력은 추진제에 낮은 밀도의 기체를 주입하여 추진제 전체의 밀도를 감소시킴으로써 추력을 조절하는 방법이다. 가변추력을 위한 이상 유동은 에어레이터에 의하여 형성되며, 와류형 분사기는 closed, open, screw-type의 세 가지 형상의 분사기를 이용하였다. 본 논문에서는 세 가지 형상의 와류형 분사기에 기체주입식 가변추력 방식을 적용하여 기체-액체 질량 비에 따른 분무차압, 혼합물의 밀도, 유량계수의 변화를 측정하였으며 기체주입식 가변추력의 가능성을 확인하였다. Thrust throttling using gas injection is method that a low density gas directly injected into propellant to reduce the bulk density of propellant. Two phase flow for thrust throttling was formed by aerator. Injectors were used Closed, open, screw-type swirl injectors. In this paper, applying thrust throttling using gas injection in swirl injector measured pressure drop, density of mixture and discharge coefficient according to gas-liquid mass ratio. Also, based on experimental results, validity of gas injection method were confirmed.
이원구 ( Wongu Lee ),이근석 ( Keunseok Lee ),안규복 ( Kyubok Ahn ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-
An Experiment was carried out to investigate the variation of spray characteristics during thrust throttling using gas injection method in the tree types of bi-swirl coaxial injectors. Thrust throttling using gas injection is a method of controlling the thrust by reducing the bulk density of the propellant by supplying low density gas into the liquid propellant. As the gas is mixed with the liquid, the propellant becomes a mixture. In the mixture, gas is exists in form of the bubbles. To analyze these mixture, the two-phase flow model was set up and spray characteristics were compared using spray angle and breakup length. The mass flow rate of the gas was set to using Gas-Liquid mass Ratio(GLR). The mass flow rate of liquid was varied by adjusting the thrust ratio from 10 to 50% based on the nominal thrust of 420 N. Spray images were taken using high speed camera and light source. One hundred images were taken with an exposure time of 2μs at sampling rate of 1000 Hz.
안종현 ( Jonghyeon Ahn ),이근석 ( Keunseok Lee ),안규복 ( Kyubok Ahn ) 한국분무공학회 2021 한국액체미립화학회지 Vol.26 No.1
Six shear coaxial injectors with different recess length and taper angle were manufactured. Cold-flow tests on the injectors were performed at room temperature and pressure using water and air as simulants. By changing the water mass flow rate and air mass flow rate, spray images were taken under single-injection and bi-injection. Breakup length and spray angle were analyzed from instantaneous and averaged spray images using image processing techniques. For all the injectors, the breakup length generally decreased as the momentum flux ratio increased at the same gas mass flow rate. The injectors with 7.5° taper angle usually had the longest breakup length and the smallest spray angle. When the taper angle was 15° or more, it hardly affected breakup length and spray angle. The recess length did not influence breakup length but its effect on spray angle depended on the taper angle.