• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.89-96
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• 2006

The combustion temperature in gas generator should be kept below around 1,000K to avoid any possible thermal damages to turbine blade by adopting either fuel rich or oxidizer rich combustion. Thus, non-equilibrium chemical reaction dominates in the gas generator. Meanwhile, Kerosene is a compounded fuel mixed with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focus to model the non-equilibrium chemical reaction of kerosene/LOX with detailed kinetics developed by Dagaut using PSR(Perfectly stirred reactor) assumption. Also, droplet evaporation time is taken into account by calculating for the residence time of droplet and by decoupling reaction temperature from the reactor temperature. In Dagaut’s surrogate model for kerosene, chemical kinetics of kerosene consists of 1592 reaction steps with 207 chemical species. The comparison of calculation results with experimental data could provide very reliable and accurate numbers in the prediction of combustion gas temperature, species fraction and other gas properties.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.12
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• pp.1201-1208
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• 2009

Dome stretching tests and tension tests were performed to evaluate the formability of a copper alloy used for manufacturing the regenerative cooling chamber. The test specimens were prepared to investigate the effect of heat treatment and direction of specimens on the formability. The test results show that forming limit values are increased by the heat treatment of the material but the variation of the forming limit values by manufacturing direction is negligible compared to the heat treatment effect, and forming limit values are also different according to the test methods. These results indicate that the high temperature heat treatment of the material before bulging is a very important process to deform the inner cylindrical structure of the regenerative cooling chamber into a nozzle shape by the bulging process without necking or fracture and the test methods also have a great effect on a evaluation of the formability. The forming limit diagram obtained in this study would be utilized to the design of regenerative cooling chamber nozzles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.9
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• pp.939-945
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• 2009

The dome stretching tests and tension tests have been performed to obtain a forming limit curve(FLC) for the copper alloy which is used for manufacturing the regenerative cooling thrust chamber. For experimental investigation of the forming limit curve, we have used in-plane tension specimen to obtain tension-compression strain state as well as out-of-plane specimen to obtain tension-tension strain state through dome stretching test. All specimens were divided into longitudinal and transverse directions according to the orientation of test specimen. The test results showed that in the tension-tension region, copper alloy revealed a maximum major strain of 62.3% and a maximum minor strain of 58.6%. In the tension-compression region, the maximum major strain and the maximum minor strain were measured to be 60.5% and 25.8%, respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.7-12
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• 2007

Swirl injector with multi-stage tangential entry was analyzed to suppress high-frequency combustion instability in Liquid Rocket Engines. In order to analyze the effect of swirl injector as an acoustic absorber, swirl injector was regarded as a quarter-wave resonator and it's damping capacity is verified in atmospheric temperature. It has a finite mode of vibration and natural frequencies which can be tuned to the natural frequencies of a model combustion chamber. When the targeted injector for each modes is located at anti-node point, the amplitude of modes was decreased. And when the injector of large diameter is mounted, the split of mode which accompanies the decrease of amplitude appeared. From the experimental data, it is proved that if the location of injector mounted is located at an anti-node position of the targeted modes with proper volume, the amplitude of modes is decreased and the split of modes occurs at anti-node point.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.1-11
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• 2017

TPTF (Turbopump Real Propellant Test Facility) at Naro Space Center has used alcohol burner system to simulate the gas flow of gas generator of liquid rocket engine. During the test at TPTF, the temperature and pressure at turbine inlet were smoothly increased while those of the gas generator of engine were constant. Present research developed a simulation code for the burner and the piping system and applied to the system. The calculation results were in good agreement with the test, and confirmed quantitatively that the non-steadiness is due to the heat transfer of the pipe. While the insulation of the pipe is ineffective, the length has a large impact on the turbine inlet condition. The present research clarified the empirically estimation of test condition, and can be applied to determination of the following test conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.46-52
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• 2018

A simple Crocco's $n-{\tau}$ time delay model and linear analysis of fluid flow coupled with acoustics are combined to investigate the high frequency combustion instability in the combustion chamber of LOX/hydrocarbon engines. The partial differential equation of the velocity potential is separated into ordinary differential equations, and eigenvalues that correspond to tangential resonance modes in the cylindrical chamber are determined. A general solution is obtained by solving the differential equation in the axial direction, and boundary conditions at the injector face and nozzle entrance are applied in order to calculate the chamber admittance. Frequency analysis of the transfer function is used to evaluate the stability of system. Stability margin is determined from the system gain and phase angle for the desired frequency range of 1T mode. The chamber model with variable baffle length and configurations are also considered in order to enhance the 1T mode stability of the combustion chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.258-261
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• 2003

The optimal design and combustion analysis of the gas generator for Liquid Rocket Engine (LRE) were performed. A fuel-rich gas generator in open cycle turbopump system was designed for 101on1 in thrust with RP-1/LOx combination. The optimal design was done for maximizing specific impulse of main combustion chamber with constraints of combustion temperature and power matching in turbopump system. Results of optimal design show the dimension of length, diameter, and contraction ratio of gas generator. The configuration of the gas generator and the condition for performance which can maximize the objective function were determined and found to meet the design constraints. Also, the combustion analysis was conducted to evaluate the performance of designed chamber and injector of gas generator. And the effect of the turbulence ring was investigated on the mixing enhancement in the chamber.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.74-84
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• 2005

This paper include the investigation of finding the system characteristics of facility by simulating open-type turbo-pump fed system, which has commercial control valves, using AMESIM (Advanced Modeling Environment Simulation) commercial software. After developing a flight-type control valve on the basis of the results, the system characteristics of facility for control and valve tests is estimated. Especially, one of purposes of this paper is to find PID value of each commercial control valve in the facility for system test. To find suitable control logic, PI and PID modes are also compared. This paper also introduces design parameters of valve and equipment for thrust control and TDS simulation, which are using control valves.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.428-432
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• 2010

A study on the forming characteristics of outer shell structure for thrust chamber nozzle extension has been performed. In order to identify anisotropy of cold rolled sheet metal, three types of tensile specimens according to the direction to the sheet rolling axis were prepared and tested, and Landford's values were obtained using the results and applied to structural analysis. Forming characteristics of the outer shell structure of the nozzle extension are investigated through manufacturing and forming of the full scale outer shell structures, and strain values obtained by the forming processes are compared to the numerical analysis results. The results obtained by this study will be utilized to design forming tools and processes for manufacturing other outer shell structures which have a bigger expansion area ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.24-33
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• 2020

In this study, model combustion tests were conducted to investigate the combustion instability characteristics of swirl coaxial injectors for a liquid rocket engine. To examine the effects of the combustion chamber resonant frequency and the injector mixing conditions, pressure fluctuations in the combustion chamber were measured by changing the combustion chamber length, injector recess length, and propellant mixture ratio. From the test results, the variation in the pressure fluctuations for each experimental condition was confirmed and the combustion stability was evaluated by stability mapping. It was found that the longitudinal mode and Kelvin-Helmholtz instabilities occurred due to the change in the combustion chamber and recess lengths.