• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.687-692
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• 2016

When turbochargers are applied to engines, the temperature of the engine becomes high, making the cooling of pistons very important. To solve this problem, an oil jet is used. The oil jet provides oil to the underside of piston for cooling. When an oil jet is used, oil pump size-up and oil cooler are needed because of the increased oil flow rate and higher oil temperature. On the other hand, these increase the friction torque of the engine. This study examined how much the friction torque of an engine increases by an oil jet, oil cooler, and oil pump size-up. In addition, the proportions of the friction torque of the engine increased by each part were measured by changing the engine assembly condition. At low speed, the oil pump and oil cooler had a larger effect on the friction torque than the other factors. At high speed, oil cooler had a larger effect than the other factors.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.42-49
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• 2014

Test device using virtual engine simulator can help reduce the number of engine tests through tests similar to the actual engine tests and repeat the test under the same condition, and thus reduce the engine maintenance and operating costs. Also, as it is possible to easily implement extreme conditions in which it is hard to conduct actual tests, it can prevent engine damages that may happen during the actual engine test under such conditions. In this study, an upgraded small jet engine performance test device was developed that can conduct both real and virtual engine test by applying real-time engine model to the existing micro jet engine performance test device that was previously developed by authors. This newly developed multi-purpose small jet engine performance test device is expected to be used for various educational and research purposes.

• Advances in Energy Research
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• v.3 no.1
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• pp.31-43
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• 2015

This paper compares the performance of JP-8(Jet Propellant) fuel and liquefied petroleum gas (LPG) and natural gas in the F110 GE100 jet engine. The cost of natural gas usage in gas turbine engines is lower than JP-8 and LPG. LPG cost is more than JP-8. LPG volume is bigger than JP-8 in the same flight conditions. Fuel tank should be cryogenic for using natural gas in the aircraft. Cost and weight of the cryogenic tanks are bigger. Cryogenic tanks decrease the move capability of the aircraft. The use of jet propellant (JP) is the best in available application for F110 GE 100 jet engine.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.50-55
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• 2006

An efficient cooling system for a piston of an automotive engine is very important. Therefore a large capacity gasoline engine or diesel engine has adopted the direct injection cooling system to increase its cooling efficiency. In this direct cooling system, an cooling oil is injected to a piston directly using an oil jet and this cooling oil flows through an oil gallery inside the piston. Flow rate and injection accuracy of this cooling oil are very important because these are main factors that have influence on its efficiency. The purpose of this study is to understand the changes of flow characteristics with various curvatures and diameters of an outlet nozzle and to check whether engine oil enters into the oil gallery well or not. From this study, we found that secondary flow was formed in a curved part of jet due to centrifugal force and irregular flow pattern appeared at the jet outlet. This pattern has influence on flow characteristics of engine oil entering the gallery. These simulation results have a good agreement with experiments.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.27-34
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• 1998

The purpose of this study is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area and its angle, the depth and shape of the piston top cavity(main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load, by the depth of the piston top cavity at the low speed and load. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.788-793
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• 2001

Test experience with a micro-turbine jet engine is introduced. The engine provides us with valuable opportunities to experience know-hows essential for engine development. It consists of a single radial compressor and a single stage turbine. Engine starting procedure has been established after many trials and errors. Static and dynamic engine performance tests were conducted. Static performance was found to be inferior to that advertised by the manufacturer. Further improvement is needed. Dynamic performance revealed that engine thrust overshoots unfavorably for the purpose of UAV control.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.84.2-84.2
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• 2011

Astrophysical jets play important roles in many interesting astronomical phenomena, such as star formation, gamma-ray bursts, and active galactic nuclei. The jets are thought to be driven by rotating disks through magneto-centrifugal processes. However, quantitative understanding of the jet-driving mechanism has been difficult because examples showing rotation in both disk and jet are rare. One of the important quantities in the models of jet engine is the size of the jet-launching region. The bipolar jet of the NGC 1333 IRAS 4A2 protostar shows a lateral velocity gradient, which suggests that the SiO jet is rotating around its axis. The jet rotation is consistent with the rotation of the accretion disk. The disk-jet rotation kinematics suggests that the jet-launching region on the disk, or the outflow foot-ring, has a radius of about 2 AU, which supports the disk-wind models.

• Journal of ILASS-Korea
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• v.11 no.3
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• pp.176-189
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• 2006

In the present study, capability of improving the liquid atomization of a high-speed liquid jet by using wall impingement is explored, and its application to a jet engine atomize. is demonstrated. Water is injected from a thin nozzle. The liquid jet impinges on a wall positioned close to the nozzle exit, forming a liquid film. The liquid film velocity and the SMD were measured with PDA and LDSA, respectively. It was shown that the SMD of the droplets was determined by the liquid film velocity and impingement angle, regardless of the injection pressure or impingement wall diameter. When the liquid film velocity was smaller than 300m/s, a smaller SMD was obtained, compared with a simple free jet. This wall impingement technique was applied to a conventional air-blasting nozzle for jet engines. A real-size air-blasting burner was installed in a test rig in which three thin holes were made to accommodate liquid injection toward the intermediate ring, as an impingement wall. The air velocity was varied from 41 to 92m/s, and the liquid injection pressure was varied from 0.5 to 7.5 MPa. Combining wall impinging pressure atomization with gas-blasting produces remarkable improvement in atomization, which is contributed by the droplets produced in the pressure atomization mode. Comparison with the previous formulation for conventional gas-blasting atomization is also made, and the effectiveness of utilizing pressure atomization with wall impingement is shown.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.115-121
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• 2004

This paper suggests the development scheme for a supersonic turbo jet engine in order to increase the performance and to reduce the weight based on the characteristics of components as well as the current technology trends.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.401-404
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• 2006

An axisymmetric simulation with detailed chemistry and fine resolution mesh is conducted for the $LOX/GH_2$ jet flame in rocket engine combustor. A preliminary result is shown for a single shear coaxial injector element. The fundamental features of the $LOX/GH_2$ coaxial jet flame is explored by the analysis of simulated flame.