• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.148-154
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• 2018

When shooting small arms, the inner surface temperature is heated up to about $700{\sim}1,000^{\circ}C$ by the friction of the bullet and the inner wall of the barrel and the combustion of propellant. High-temperature propellant gas and high-speed movement of the bullet cause corrosion of the inner wall, which is noticeable immediately in front of the chamber. In this study, the mechanical properties of Cr-Mo-V steel, which is the base material, were tested using Taguchi experimental design to find the best nitriding treatment conditions. For the nitriding process, the working time, salt bath temperature, and salt concentration were combined as three conditions and placed in the $L_9(3^4)$, orthogonal array table. The thicknesses of the white layer and the nitrogen diffusion layer were measured after nitriding under each condition in a salt bath furnace. Durability was evaluated by measuring the degree of dispersion through actual shooting because it was difficult to evaluate the mechanical properties of the cylinder inner structure. As a result, it was confirmed that the durability was optimal at $565^{\circ}C$, 1 hour, 0.5%. These optimal conditions were selected by the statistical analysis of the Minitab program(ver.17).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.552-561
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• 2018

Biomass, a carbon-neutral resource, is an alternative energy source for exhaustion of fossil fuel and environmental problems. Most of energy production systems using biomass operate with a thermal chemical conversion method. Amongst them, gasification generates syngas and applies to boilers or engines for the production of heat and electricity. However, Tar could be formed during the production of syngas and it is condensed at low temperature which may cause to clog the pipelines and combustion chamber, ultimately resulting in decrease of process efficiency. Thus this work utilized water and oily materials such as soybean oil, waste cooking oil and mineral oil for scrubbing liquid. The removal efficiency of Tar appeared 97%, 70%, 63% and 30% for soybean oil, waste cooking oil, mineral oil and water respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.53-62
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• 2010

An airbag is composed of housing assembly, door assembly, cushion assembly, and an inflator. The inflator is the essential part that generates gas for airbag. When an airbag is activated, it effectively absorbs the crash energy of the passenger by inflating a cushion. In this study, tank tests were performed with newly synthesized propellants with various compositions, and the results are compared with the numerical results. In the simulation of inflator, a zonal model has been adopted which consisted of four zones of flow regions: combustion chamber, filter, gas plenum, and discharge tank. Each zone was described by the conservation equations with specified constitutive relations for gas. The pressure and temperature of each zone of the inflator were calculated and analyzed and the results were compared with the tank test data. In the zone of discharge tank the pressure quickly rose, the pattern of pressure curve was very similar to the pressure curve of real test. And in zone 1 & 2 & 3 the mass of products was increased and decreased with time. In zone 4, the mass of products was increased with time like real inflator. From the similarity of pressure curve in zone 4 and closed bomb calculation the modeled results are well correlated with the experimental values.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.14-17
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• 2008

A poppet type shutoff valve under the pneumatic control has been adapted for the MOV (Main Oxidizer shutoff Valve) for KSLV (Korea Space Launch Vehicle). The MOV controls the supply of liquid oxygen into the combustion chamber just by opening and shutting operations. The poppet part of the poppet valves is usually connected with the piston, but on the other hand that of the MOV is separated and just contacted with the piston in order to secure the flexibility of the valve design. For the prevention of the collision with valve body by an undesirable movement of the piston part, it is necessary to evaluate the force during the valve closing. The analysis of the force balance of the MOV at the moment of the valve closing have been performed and some important design parameters for the force balance control have been introduced.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.81-90
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• 2004

This paper describes the results of combustion performance test of fuel-rich gas generator(GG) using LOx and kerosene as propellant at off-design conditions. The chamber pressure is thought to be a function of O/F ratio and total propellant mass flow rate. The test shows that the spatial temperature deviation at the exit of gas generator remains within 7.5K and that the average gas temperature at the exit is a function of propellant O/F ratio. The results of firing test of gas generator at off-design conditions, especially the relation between gas temperature and O/F ratio, can provide useful data for the design of future gas generator and for the development of low-O/F ratio reaction analysis code.

• Journal of ILASS-Korea
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• v.25 no.1
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• pp.8-14
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• 2020

Recently, 1-D model-based engine development using virtual engine system is getting more attention than experimental-based engine development due to the advantages in time and cost. Injection rate profile is the one of the main parameters that determine the start and end of combustion. Therefore, it is essential to set up a sophisticated model to accurately predict the injection rate as starting point of virtual engine system. In this research, procedure of 1-D model setup based on AMESim is introduced to predict the dynamic behavior and injection rate of diesel injector. As a first step, detailed 3D cross-sectional drawing of the injector was achieved, which can be done with help of precision measurement system. Then an approximate AMESim model was provided based on the 3D drawing, which is composed of three part such as solenoid part, control chamber part and needle and nozzle orifice part. However, validation results in terms of total injection quantity showed some errors over the acceptable level. Therefore, experimental work including needle movement visualization, solenoid part analysis and flow characteristics of injector part was performed together to provide more accuracy of 1-D model. Finally, 1-D model with the accuracy of less than 10% of error compared with experimental result in terms of injection quantity and injection rate shape under normal temperature and single injection condition was established. Further work considering fuel temperature and multiple injection will be performed.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.113-119
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• 2013

A main oxidizer shut-off valve (MOV) controls the supply of cryogenic liquid oxygen to the combustion chamber of liquid rocket engines by on/off operations. The main subjects to be introduced are not only the valve transient response during valve on/off procedures but also the characteristics of pneumatic and seat/poppet parts as core technologies in the development of the MOV, which is expected to be adopted for the Korea Space Launch Vehicle II. It is shown that the analytical prediction of the transient valve travel is in good agreement with experimental results. Friction and elastic forces on the valve moving part are quantitatively evaluated by structural analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.957-967
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• 2017

Firing test of the fuel grain for solid fuel ramjet with additives and ignition support material was conducted. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Boron particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. An oxidant gas having a controlled temperature, pressure and oxygen composition close to the air condition in the ramjet combustor was supplied using the Ethanol blended $H_2O_2$ gas generator. Gas was set to flow at a mass flow rate of 150 g/s and mass flux of $200kg/m^2s$ in the grain port. Through the test, ignition support operated well and ignition delay of 0.5. During the test, stable chamber pressure with 8 bar and high combustion efficiency of 0.86 was confirmed.

• Journal of the Korean Society of Propulsion Engineers
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• v.27 no.1
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• pp.58-67
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• 2023

Results of dry-run tests, cold-flow tests, and hot-firing tests performed to throttle a methane engine uni-element thrust chamber are covered in the paper. After installing flow control valves on the oxidizer and fuel supply lines of the methane engine combustion test facility, a number of dry-run tests were repeated so that the valves could reach set strokes quickly and stably. Then, cold-flow tests using liquid nitrogen and gaseous nitrogen were conducted to confirm the stable supply of the simulated propellants according to the valve control. Finally, using liquid oxygen and gaseous methane, hot-firing tests for fixed and continuous thrust control of 50% to 10% of the nominal thrust were successfully performed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.2
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• pp.179-188
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• 2011

Experiments were conducted in a constant-pressure combustion chamber to investigate the effects of hydrocarbon addition on cellular instabilities of syngas-air flames. The measured laminar burning velocities were compared with the predicted results computed using reliable kinetic mechanisms with detailed transport and chemistry. The cellular instabilities that included hydrodynamic and diffusional-thermal instabilities of the hydrocarbon-added syngas-air flames were identified and evaluated. Further, experimentally measured critical Peclet numbers for fuel-lean flames were compared with the predicted results. Experimental results showed that the laminar burning velocities decreased significantly with an increase in the amount of hydrocarbon added in the reactant mixtures. With addition of propane and butane, the propensity for cell formation was significantly diminished whereas the cellular instabilities for methane-added syngas-air flames were not suppressed.