• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.69-72
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• 2011

Hot-firing tests were performed on the third sub-scale gas generator for development of a 75 ton-class liquid rocket engine. This paper deals with the analysis results of low-frequency combustion instabilities that were encountered during combustion tests of the gas generator. The low-frequency pressure fluctuations seem to be related to chamber pressure and pressure drops through oxidizer/fuel injectors.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.1-9
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• 2020

Using kerosene and liquid oxygen, 1.5-tonf class liquid-liquid pintle injector with rectangular two-row orifice was designed and manufactured. The combustion test of the pintle injector was carried out to verify the combustion performance and combustion stability under a supercritical condition which is the actual operation condition of the liquid rocket engine. The combustion test result showed that the pintle tip was damaged by the high temperature combustion gas in the high-mixed ratio recirculation zone of the combustion chamber. To solve this problem, the insert nozzle was installed in the pintle injector to increase cooling performance at the pintle tip. As a result of the hot firing test, installation of the insert nozzle, AR and BF had a great effect on pintle tip cooling performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.26-26
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• 1998

우주항공 산업에 대한 관심 증가에 따라 지상에서 많은 연소시험을 시행하고 있으나, 소음 발생문제에 부딪혀 어려움을 겪고 있는 실정이다. 따라서 초보적 단계이기는 하나, 액체로켓 엔진의 추력 손실을 최소화시키고 최대한 제트 소음을 크게 줄일 수 있는 소음기를 연구, 개발하고 있다. 본 연구에서는 제트소음에 대한 기초연구를 수행하여 물분사형 소음기를 설계 및 제작하였고, 물분사량과 소음기의 기하학적형상이 소음 특성에 미치는 영향을 연구하였다. 본 실험범위에서 연구의 결과는 다음과 같다. 1. 동일한 물 분사량 조건에서, 소음기 길이가 노즐출구 직경의 10배 모델 보다 30배 모델이 9dbl 정도 감음효과를 보였다. 2. 불 분사량이 증가함에 따라 소음레벨은 감소하였고, 30배 모델의 경우 불분사량이 배기가스의 10-12배 조건에서는 소음레벨을 91dbl까지 줄일 수 있었다. 3. 상기조건(소음레벨 91dbl)에 확장관을 부착함으로써, 소음레벨을 약 86dbl까지 줄일 수 있었다. 4. 본 형태의 물분사방식을 채택할 경우 고온배기가스로 인한 소음기의 파손을 방지하기 위해서 반드시 막냉각장치의 설치가 요구된다.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.28-33
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• 2009

Natural gas is the world's most plentiful combustible fuel, abundantly acailable in all continent. A fuel injector designed specifically for low energy density gaseous fuels has been developed. The injector incorporates design features that are necessary to optimize the performance for fuels such as CNG, LNG. Gaseous fuel injectors have a decisive influence upon starting performance, driveability, fuel consumption and exhaust emissions. A gaseous fuel injector has been developed to cope with the considerably larger volume flow rates and the developed gaseous fuel injector could be used at heavy duty natural gas engine. The static flow of injectors at various inlet pressure was directly proportional and the controllability showed great performance.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.3
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• pp.1-6
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• 2007

A 3-tonf-class high pressure sub-scale combustor was designed and manufactured to study the performance improvement of combustor. The combustor consists of a combustion chamber with film cooling, thermal barrier coating and water cooling channels to prevent thermal demage of the hardware and an injector head with 37 coaxial swirl injectors. Hot-firing tests were carried out at the design point with varying flow rate for film cooling. The test result revealed that the increase of film cooling flow rate decreases the combustion performance, but in the cases of similar film cooling flow rates, the combustion performance is dependent on the mixture ratio of main injector excluding the film cooling flow rate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1019-1024
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• 2011

The gaseous fuel injection(GFI) type of LPG fuel-supply system is more advantageous than liquefied fuel injection(LFI) from the viewpoint of durability and cost reduction. However, compared with LFI types of LPG fuel-supply systems, in the GFI systems it is difficult to achieve precision fuel metering because of the compressible characteristic of the gaseous fuel. In this study, a Helmholtz resonator is proposed as an appropriate system for precision fuel metering in GFI systems, and the effects of the Helmholtz resonator on the fuel metering are simulated by the commercial flow-network-analysis package Flowmaster.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.265-272
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• 1999

A thrusters modulation method is suggested for spacecraft attitude control with asymmetric configured thrusters during orbit adjustment maneuvers. Attitude is controlled by thrusters off-modulation during orbit maneuvers. Usual control method for symmetric configured thrusters cam not be applied for asymmetric configured thrusters. Disturbance induced from thrusters asymmetricity shall be compensated during pulsing. In this paper, a thrusters control method using null solution is suggested, which is shown working well without inducing disturbance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.76-80
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• 2012

Uni-element preburners using a oxidizer-rich triplex injector have been designed and tested. During combustion tests 1L mode high-frequency instability of 1100 Hz and low-frequency instability of 100 Hz were observed. High-frequency instability has been suppressed by reducing chamber diameter and applying turbulent rings in combustion chamber. Recently, research to reduce low-frequency instability is in progress.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.92-100
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• 2005

An optimal fuel manifold is suggested to improve the cooling performance of an injector face plate. The cooling performance at the center area of the injector face plate is to be augmented while the spatial injection uniformity is maintained. The comparison of the cooling performance of f candidates gives the conclusion that the dividing plate from 2-3 injector .ow to 9-10 injector. row is an optimal. The maximum face plate temperature decreases by 27$\%$ while the injection uniformity is close to that of the original design. The pressure drop in the fuel manifold of the optimal design is also same as the original design.

• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.81-89
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• 2018

In the present study, a numerical investigation was conducted to analyze the effect of the distance between the adjacent injectors on the characteristics of flow structure, fuel penetration, and air/fuel mixing. Numerical results were validated with experimental data using a single injection. Subsequently, the same injector geometry and properties were applied on a non-reacting flow simulation with multiple injectors. Total pressure loss, penetration height, and mixing efficiency were compared with the distance between the injectors. The results showed that each injected gas merged into a single stream, resulting in the 2D-like flow fields under the condition of short distance and lower mixing efficiency along with higher total pressure loss. When the distance between the injectors increased, total pressure loss reduced and mixing efficiency increased due to the weakening of interactions between the injected gases.