• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.4-4
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• 1999

최근 충남대에서는 다양한 추진제와 연소 조건으로 액체로켓 연소 실험이 진행되고 있으며 그에 비례하여 많은 사고들이 발생하고 있다. 한 예로 GO$_2$/kerosene을 추진제로 하는 노즐삭마 시험용 로켓엔진(추력 1001bf, 연소실 압력 600psia) 개발 중에 화염이 인젝터면에 형성되어 인젝터면을 손상시키는 사고를 여러 번 경험하게 되었다. 본 연구는 인젝터 손상의 원인을 규명하여 안정적인 인젝터 설계에 도움을 주기 위한 목적으로 실험용 동축 인젝터를 제작하여 화염 부상 특성을 실험적으로 연구하였다. 사용된 인젝터는 연료인 Kerosene을 접선형 선회기로부터 90$^{\circ}$의 원뿔 각을 가지고 분무되도록 설계하였으며, 그 주위로 산하제인 GO$_2$가 연소실의 축방향에 수평하게 분무되도록 설계하였다. 2-유체 동축 인젝터의 난류 확산 화염에서 연료와 산화제의 혼합은 화염 특성을 결정하는 주요 변수이므로 인젝터로부터 분무되는 추진제간의 유량을 변화시켜 화염 부상 특성을 연구하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1361-1369
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• 2013

This study performs a computational fluid dynamics (CFD) analysis of the inner flow of a multihole injector nozzle by using ANSYS CFX 13.0. Based on the obtained results, a design of experiment (DOE) was performed and applied to investigate the effects of injector nozzle design parameters on cavitation. To analyze the design sensitivity and signal-to-noise ratio (S/N ratio), the hole diameter, hole length, hole angle, and K-factor of the nozzle hole were selected as design parameters, and the effect of these parameters was investigated at 16 experimental points. Consequently, it was found that the effect of the K-factor on the cavitation and inner flow of the injector nozzle is the greatest. Thus, the selection of a suitable K-factor is important in nozzle design considering cavitation flow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.650-655
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• 2016

In this study, a computational simulation of the internal flow characteristics was carried out for a Urea-SCR Injector. A single hole swirl injector with a swirl disk and slanted nozzle was used in this simulation. The maximum needle lift and opening velocity were selected as the design parameters. To analyze the unsteady internal flow characteristics of the Urea-SCR injector, the moving grid technique was applied to simulate the delicate needle movement. According to the simulation results, the injected mass flow rate from the Urea-SCR injector decreased with increasing needle opening velocity and maximum needle lift. This is because the Urea-solution tends to fill the empty space that the needle previously occupied. The swirl flow is decreased as the flow goes through the injector nozzle, because of the friction with the nozzle wall. Also, during the maximum needle lift period, the swirl coefficient and mean swirl coefficient increase with increasing needle lift. The results of this study may be used as the basic design data of related injectors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.62-68
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• 2005

An injector for fuel rich gas generator was designed and experimentally investigated. Five variations of F-O-F triplet impinging type injector were tested to evaluate spray characteristics with kerosene/water simulant propellant. Test was focused to find the effect of design variables of impinging angle, and impinging distance, on the atomization performance. A mixing efficiency is used to compare droplet distribution and local O/F ratio of each injector in the range of momentum ratio of 0.2~1.3. Test results shows the max value of mixing efficiency locates about the 0.8 in momentum ratio. And the injector with an impinging angle of 45 degree and impinging distance of 6mm shows the very good performance result suitable for fuel rich gas generator. A combustion test will be also conducted with selected injector to verify the spray pattern and mixing efficiency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.153-156
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• 2003

Backhole, which is one of geometric parameters in swirl coaxial injectors, is found to affect the inner flow motion and the acoustic characteristics of the swirl injector. In order to analyze the effect of the backhole as a damping device such as acoustic cavities of the combustion chamber, it was regarded as a Helmholtz or Quarter-wave resonator. As a result, it is known that the swirl coaxial injector with the backhole may produce the resonant frequency coincided with the frequency of the combustion chamber.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.4
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• pp.137-144
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• 2006

The basic data obtained in this research for single element performance were directly applied to the design of injector head(7 elements). Designed performance of the 7-element Swirl Coaxial injector was $245kg_f$ sea level thrust with 20bar combustion chamber pressure. Numerical analysis were performed to obtain the change of spray pattern for the design of injector head, and we confirmed the feasibility and application of those results. Hot tests were performed for the multi-element injector to compare with the performance of the single element injector and those can be applied to the design of scaled liquid rocket engine. The basic data obtained in this research can be directly applied to the real liquid rocket injector design.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.107-114
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• 2009

A Common-Rail Direct Injection (CRDI) system for high speed diesel engines was developed to meet reductions of noise and vibration, emission regulations. High pressure in the common rail with electric control allows the fuel quantity and injection timing to be optimized and controlled throughout a wide range of engine velocity and load conditions. In this study, CRDI system analysis model which includes fuel and mechanical systems was developed using commercial software, AMESim in order to predict characteristics for various fuel injection components. The parameter sensitivity analysis such as throttle size, injection rate, plunger displacement, supply pressure of fuel injection for system design are carried out.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.7-7
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• 2000

액체추진 로켓 분야에서 비연소 혼합시험(cold flow mixing test)은 로켓엔진의 성능을 예측하고 인젝터와 관련된 문제의 진단에 도움을 줄 수 있는 자료를 확보할 수 있는 수단이 된다. 비연소 혼합시험이 실제 연소시험을 대신할 수 있는 신뢰성 있는 자료를 제공할 수는 없지만, 인젝터의 최적형상을 설계하기 위해서 실시해야할 고 비용의 연소시험에 대한 횟수를 줄일 수 있는 보조시험으로서의 역할을 할 수 있다. 혼합시험 성능이 우수한 인젝터가 수력학적인 혼합성능을 능가하는 연소반응에 의해서 실제 연소시험에서는 성능이 저하되는 경우도 있을 수 있으나 대부분의 경우에는 비연소 혼합시험에서 좋은 성능을 나타내는 인젝터는 실제 연소시험에서도 좋은 성능을 나타낸다. 일반적으로 비연소시험과 연소시험 사이의 상관 관계를 정확히 정립하기 위해서는 많은 상관 관계 변수의 적용 및 충분한 혼합시험 자료가 요구된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.146-149
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• 2006

Spray characteristics of an injector employed in mono-propellant hydrazine thrusters were investigated by PIV(particle image velocimetry) and LDA/PDA(laser/phase Doppler anemometry) techniques. The instanteneous plane image data captured by PIV measurement were examined in order to judge a pass-fail criteria of spray injection performance according to the specific pressure supplied. LDA/PDA technique were also applied to measure the velocity and droplet size of spray were not obtained from PIV measurement. The objective of this experimental study was the clear understanding of spray characteristics as well as the derivation of injector performance to understand clearly the spray characteristics by comparing the both results.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.3
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• pp.50-57
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• 2007

Spray characteristics of an injector in a small liquid rocket engine (LRE) is characterized by Particle Image Velocimetry (PIV) and Dual-mode Phase Doppler Anemometry (DPDA). Instantaneous plane images captured by PIV are examined for the qualitative prediction of spray breakup with the setup of evaluation technique for effect of spray angles on injector performance. DPDA is also applied in order to quantify the average velocity, turbulent intensity, SMD, and number density of spray droplets along the spray stream distance leading to precise observation of spray atomization behavior. An objective of the study is the derivation of design parameters of new injectors and the establishment of performance criteria through the clear understanding of spray characteristics.