• 한국연소학회:학술대회논문집
• /
• 2003.12a
• /
• pp.125-130
• /
• 2003

본 논문에서는 액체로켓엔진에서 터보펌프의 160kW급 터빈을 구동하고, 액체산소와 케로신을 추진제로 사용하는 가스발생기의 설계점 연소성능시험 결과에 대해 논의하였다. 충돌형 F-O-F 인젝터, 물냉각 채널을 가진 연소실, torch ignitor, turbulence ring 그리고 측정 링을 갖는 가스발생기에 대해 기술하였고, 점화, 연소, 종료 등의 시험 cyclogram에 대해 언급하였다. 설계점에서의 연소시험 및 turbulence ring 장착여부, 연소실 길이 변화에 따른 연소시험의 결과들에 대해 기술하였다. 연소시험 결과 가스발생기는 설계점에서 안정된 작동성을 보여주었고, 연소압력 및 온도 등의 성능이 예측치에 근접하는 결과를 보여 주었다. Turbulence ring은 출구에서의 가스온도를 균일하게 분포시켜 효과적인 혼합 장치임을 보여 주었고, 4-6msec 정도에서의 잔류시간에서는 연소효율의 차이가 크지 않음을 알 수 있었다. 가스발생기 출구에서의 온도는 공급되는 추진제의 O/F ratio에 따라 매우 민감하게 반응함을 알 수 있었다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.1
• /
• pp.54-60
• /
• 2004

Experimental study on combustion characteristics of double swirl coaxial injectors has been conducted for the assessment of critical injector design parameters. A reusable, subscale thrust chamber has been fabricated with a water-cooled copper nozzle. Two different configurations of injectors have been tested for the understanding of the effects of recess length on high pressure combustion. Clearly, the recess length drastically affects the combustion efficiency and hydraulic characteristics of an injector. Internal mixing of propellants in an injector with recess number of two increases a combustion efficiency and reveals sound combustion although a pressure drop required for the same amount of mass flow rates increases compared with an injector of recess number of one.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.726-728
• /
• 2010

A subscale gas generator was designed and manufactured to investigate the effect of design parameters on discharge coefficients of injectors for a 75 ton-class gas generator and hot-firing tests were successfully performed. The test results showed that discharge coefficients of fuel and liquid oxygen injectors remained nearly constant irrespective of variations of a mixture ratio and a chamber pressure. When the post diameter of the liquid oxygen injector was reduced, the discharge coefficient was increased as the pressure drop of the injector was decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.457-460
• /
• 2012

Design and fabrication of a sub-scale thrust chamber for verification of 7 tonf-class thrust chamber injectors were described in this paper. The 7 tonf-class thrust chamber consists of mixing head with 90 coaxial swirl injectors and regeneratively combustion chamber cooled by kerosene. The coaxial swirl injectors with different pressure drop and recess number were designed for 7 tonf full-scale thrust chamber. By applying the designed injectors to the sub-scale thrust chamber before applying them to the full-scale thrust chamber, the injector performance and functioning were verified. The sub-scale thrust chamber consists of 19 injectors, has chamber pressure of 70 bar, total propellant mass flow rate of 4.3 kg/s, mixture ratio(O/F) of 2.45.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.729-732
• /
• 2010

The present study has been motivated by the development of a reliable numerical methodology for simulation of kerosene/LOx coaxial swirl injectors. To deal with thermodynamic non-ideality and anomalies of transport properties pronounced at supercritical pressures, a set of subroutine libraries has been constructed based on the cubic equations of state, and applied to an existing flamelet analysis code. For computational efficiency, two-dimensional axisymmetric RANS formulation with swirl was adopted and validated successfully against an isothermal coaxial swirling jet. For the actual problem with high pressure combustion, however, numerical results show that the RANS models yield excessive production of turbulence probably due to high density gradient magnitude in the vicinity of mixing layer of swirling film flow, and imply strongly further improvement of the turbulence models.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.4
• /
• pp.61-66
• /
• 2004

The objective of the present study is to develop methodology for the assessment of combustion stability of liquid rocket injectors. To simulate actual combustion occurring inside of a thrust chamber, a fullscale injector has been employed in the study, which bums gaseous oxygen and mixture of methane and propane. The main idea of the experiment is that the mixing mechanism is considered as a dominant factor significantly affecting combustion instability in a fullscale thrust chamber. A single split triplet injector has been used with an open-end cylindrical combustion chamber. The characteristics revealed by excited dynamic pressures in gaseous combustion show degrees of relative acoustic damping depending on operating conditions. Upon test results, the direct comparison between various types of injectors can be realized for the selection of the best design among prospective injectors.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.2
• /
• pp.1-8
• /
• 2013

This study presents relations between the time lag and interaction index of the impinging-jet injectors using the time lag model in a model chamber. The response of the flame is analyzed to artificial perturbation with 5% amplitude of oxidizer speed at a resonance frequency. At the mixing point of fuel and oxidizer, which determines the characteristic length, the relationship between velocity perturbation and heat release rate is quantified by combustion parameters of interaction index and time lag. In this method, time lag or delay is calculated by the characteristic length and the average velocity obtained from numerical results. The tendency that the time delay decreases with axial jet velocity has been observed.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.2
• /
• pp.10-17
• /
• 2004

The results of the combustion performance tests of gas generator which supplies hot gas into the turbine of turbo-pump for liquid rocket engine and uses LOx and kerosene as propellant are described. The gas generator consists of a injector head with F-O-F impinging injector, a water cooled combustion chamber, a gas torch igniter, a turbulence ring and an instrument ring. The effect of turbulence ring and combustion chamber length on performance of gas generator are investigated. The ignition and combustion at design point are stable and the pressure and gas temperature at gas generator exit meets the target. The turbulence ring installed at middle of chamber effectively mixes hot gas with cold gas and the effect of residence time of hot gas in gas generator on combustion efficiency is small. Test results show that the main parameter controlling the gas temperature at gas generator exit is overall O/F ratio.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.10
• /
• pp.701-708
• /
• 2022

Since the propellant tank structure of the projectile is mainly subjected to a compressive force, there is a high risk of damage due to buckling. Large and lightweight structures such as propellant tank have a complex manufacturing process. So it requires a non-destructive test method to predict buckling load to use the structure after testing. Many studies have been conducted on Vibration Correlation Technique(VCT), which predicts buckling load using the relationship between compressive load and natural frequency, but it requires a large compressive load to predict the buckling load accurately, and it tends to decrease prediction accuracy with increasing internal pressure in structure. In this paper, we analyzed the causes of the decrease in prediction accuracy when internal pressure increases and proposed a method increasing prediction accuracy under the low compressive load for being usable after testing, through VCT combined testing and FEA result. The prediction value by the proposed method was very consistent with the measured actual buckling load.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2010.09a
• /
• pp.335-339
• /
• 2010

본 연구는 현재 "디지털지적시범사업" 지구의 면적증감필지의 청산방법에 있어서 현재 17개 시범지구의 통일성이 없어 사업수행에 큰 차질을 빚고 있는 문제점의 개선을 위해 실효성 있는 지적재조사를 위한 방안으로 시범지구의 청산방법실태를 분석을 통해 전국적으로 제일 많이 존재하는 불부합 유형인 편위형과 불규칙형을 중심으로 1/600, 1/1200의 축척별 면적증감량에 따른 청산금을 비교 평가하였다. 또한 저비용 고효율의 새로운 면적청산모형을 제시하여 향후 지적재조사 추진과정의 가장 핵심사항으로 제기될 증감면적의 비용조정에 따른 모형을 제시하였다. 따라서 본 연구는 연구지역 전체의 면적증감량을 분석하고 그에 따른 개별공시지가, 감정평가액, 유사평가액, 혼합평가액의 모형에 따른 모형별 청산금의 납부 정수비용을 평가하였다.