• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.1-10
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• 2019

The wave motion inside the nozzle is known as one of the major damping elements of the rocket's combustion instability by it's aeroacoustic effects that result from the flow passage through the nozzle throat. These effects can be quantitatively evaluated by the nozzle admittance. In this study, one-dimensional linearized Euler equation was adopted to calculate the nozzle admittance, and trend analysis was performed depending on the nozzle's main design variables. As a result, when nozzle converging part shortens, it is verified that the frequency dependency of the nozzle admittance is decreased due to the widened frequency range with lowered longitudinal nozzle admittance. Also, admittance estimation using the short nozzle theory is not appropriate when the first tangential mode of the pressure perturbation arises.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.108-116
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• 2018

A firing test of the 75 tonf-class liquid rocket engine to be used as the first and second stage engines of the KSLV-II was carried out at the rocket engine test facility(RETF). Since this engine uses liquid oxygen as the oxidizer, which is a cryogenic fluid, it is essential that the chill down of the supply pipe line and engine proceed for the firing test; thus, the given inlet requirements must be met. Moreover, it is important to understand the chill down characteristics of the facility and the engine and the amount of liquid oxygen consumed in the chill down process for efficient test operation in the future. In this paper, chill down characteristics of the supply pipe and the engine were evaluated through the investigation of the chill down process of the 75 tonf-class liquid rocket engine at each stage before and after run tank pressurization. In addition, the amount of liquid oxygen consumed was also evaluated.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.64-71
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• 2018

It is essential to understand the characteristics of gas turbine components in order to carry out an off-design analysis of a gas turbine engine. In this study, a micro gas turbine engine test system was constructed to understand the performance characteristics of gas turbines. The temperature and pressure in the flow path of the micro gas turbine was collected by measuring the engine spool speed, and a compressor map was constructed by using the experimental data. The exhaust gas was collected at the turbine outlet and the combustion efficiency was calculated. An off-design performance analysis at ground static was performed using GasTurb software by applying the compressor map and combustion efficiency obtained from the experimental data. Futhermore, we compared and evaluated the analysis results with engine operating data.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.84-91
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• 2010

For the successful development of 75-tonf-class liquid rocket engine, a plenty of tests on each engine component have to be performed and this is equally true for a combustor. However the test facility which is in operation at Korea Aerospace Research Institute lacks its capacity to perform fire tests of a 75 tonf class combustor at its nominal thrust. Since the test facility has to be ready prior to the start of development tests, it is very urgent to establish the test facility. The preliminary design of a test facility for a 75 tonf class combustor which was performed according to such a necessity is described in the paper.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.42-49
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• 2021

As a measure of susceptibility on the combustion instability, thermo-acoustic instabilities in rocket combustion system was considered for the estimation of the operational stability margin. Growth rate, which governs the asymptotic stability behavior of the system, was determined from the dynamic data measured during combustion tests in order to understand the dynamic characteristics of combustor system. Frequency transform technique was first applied to determine the system parameters such as growth rate and/or damping coefficient for an interested mode from the time series pressure data, and the PDFs of pressure amplitude were extracted from the amplitude envelope of pressure oscillation for the stochastic analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.70-78
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• 2014

A numerical study has been conducted to investigate flow and heat transfer characteristics of supersonic second throat exhaust diffusers for high altitude simulation. By changing pressure and configuration, flow and cooling characteristics of the diffuser have been studied. At the normal operation of the diffuser, there were high temperature regions over 3,000 K without cooling, especially near wall and in subsonic diffuser part. If the cooling system of the diffuser is added, flow velocity is increased due to the cooled wall temperature.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.142-148
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• 2018

To improve the performance of a launch vehicle, kerosene, a launch vehicle fuel, undergoes a densification process. Liquid nitrogen injection cooling is an effective densification method which has a simple system and is inexpensive. During the cooling process, however, nitrogen may dissolve in the kerosene, possibly resulting in changes to fuel properties. Therefore, it is essential to measure and eliminate the amount of dissolved nitrogen in the kerosene. In this study, the vacuum extraction principle is introduced to measure the content of dissolved nitrogen in the kerosene. In addition, the experimental results, which used a designed/manufactured nitrogen sampling device, are described. From the results, the validity of the nitrogen sampling device and the dissolved nitrogen measurement/elimination methods was demonstrated.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.374-382
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• 2014

This paper presents the computational aerodynamic analysis of a long-endurance UAV that was developed by the Korea Aerospace Research Institute (KARI), named EAV-2. EAV-2 is a technical demonstrator of aerodynamically efficient design, as well as a hybrid electric-propulsion system for future long-endurance UAVs. We evaluated the aerodynamic characteristics of six low-Reynolds number airfoils, using a panel method code, XFOIL, to select an optimal airfoil for the long-endurance mission of EAV-2. The computational results by a CFD code, FLUENT, suggested that the aerodynamic performance of EAV-2 would be notably improved after adopting SG6043 airfoil, and modifying the fuselage design. This reduced the total drag by 43%, compared to that of a previous KARI model, EAV-1, at the target lift of $C_L=1.0$. Also, we achieved a drag reduction of approximately 14% by means of the low-drag fuselage configuration.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.297-299
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• 2012

Korea Aerospace Research Institute has been doing researches on the hypersonic propulsion system and hypersonic wind-tunnel since 2000 and started scramjet engine researches from 2005. Total 5 kinds of scramjet engine were designed and tested and two of them were hydrocarbon-fueled scramjet engine. For verifying the own characteristics of each components like the intake and combustor, several component tests were done at the KSPC of JAXA and KARI. In this paper, current scramjet engine research activities of KARI will be described.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.81-86
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• 2013

This article deals with the manufacturing and performance evaluation on the specimen pipes which have large size diameter and thin thickness. This specimen is for LOX main pipe of KSLV-II propulsion feeding system. The material of specimen is alloy 21-6-9. Alloy 21-6-9 has higher strength and better weldability rather than STS-300 class pipes. We found that the specimen using alloy 21-6-9 satisfied the requirement by pressurization tests.