• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.301-302
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• 2012

During a last decade, detonative combustion is promising combustion mechanism of high-speed propulsion systems, but is more rigorously considered in these days as a game-changer for the improvement of thermodynamic efficiency of propulsion and power generation systems. Regardless of the skepticism about the pressure loss associated with the strong shock waves, it is shown that the additional compression by the strong shock wave exhibits increased thermodynamics efficiency that is not achievable by conventional compression systems. Present talk will give an introduction to the concepts and the recent activities on the pressure gain combustors (PGC) researches based on detonation phenomena.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.237-240
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• 2006

Hybrid propulsion systems provide many advantages in terms of stable operation and safety. However, classical hybrid rocket motors have lower fuel regression rate and combustion efficiency compared to solid propellant rocket motor. Accordingly, the recent research efforts are focused on the improvement of engine efficiency and regressionrate in the hybrid rocket engine. The present study has numerically investigated the combustion processes and the flame structure in the hybrid rocket engine. The turbulent combustion is represented by the flamelet model and Low Reynolds number $k-{\varepsilon}$turbulent model is employed to reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect. Numerical results suggest that the present approach is capable of realistically simulating the combustion characteristics of the hybrid rocket engines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.246-249
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• 2003

The propeller of the propulsion system for a target drone has been designed. Vortex theory has been applied to the propeller design method. This method analyze the propeller performance according to the design parameters. The optimum design has been aimed to maximize the efficiency. The performance of the designed propeller has been analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.117-121
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• 2003

In order to investigate the performance characters of the ramjet propulsion, at the first step, in this paper Ideal Brayton cycle is adopted. In the Ideal Ramjet cycle some of the Parameters are independent of the heat input, for example thermal efficiency but in the Ideal Brayton cycle, Mach number and the entry temperature of the combustion chamber are important variables with the heat input.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.272-275
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• 2007

The combustion efficiency of the solid fuel ramjet is affected by the inlet air temperature. And this inlet air temperature is dependent on the flight Mach number and the environment air temperature. If the flight altitude is changeable, the inlet air temperature and also the air density vary. The performance efficiency is investigated with this variables related to the combustion efficiency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.371-377
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• 2009

The propulsion system of turboprop has been rarely used in the large aircraft due to the limitation of the maximum velocity of the propeller, the power limitation by the reduction gear, etc. Recently, the demand on turboprop aircraft continues to increase because of economical efficiency and environmental factors. In this paper, turboprop propulsion system which is composed of a Pratt & Whitney 127F turboprop engine and a Hamilton Standard 568F propeller was modeled by using the Gasturb11 software. The result of the performance analysis on this propulsion system model showed that the propulsion system model was evaluated to have been successfully builded.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.485-492
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• 2015

Small advance ratio and low Reynolds number of stratospheric propulsion system bring lots of challenges to the design of propellers. Contra-rotating propeller configuration is proposed to improve the propulsion efficiency. In this paper, the feasibility of contra-rotating propeller for stratospheric airship has been assessed and its performance has been investigated by wind tunnel tests. The experimental results indicate, at relatively low Reynolds number, although the advance ratio is fixed, the performance of propellers is different with variation of Reynolds number. Moreover, at the same Reynolds number, the efficiency of contra-rotating propeller achieved appears to be a few percent greater than that for a standard conventional propulsion system. It can be concluded that contra-rotating propellers would be an efficient means to improve the performance of stratospheric airship propulsion system.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.376-383
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• 2012

Owing to rapid development of power device and inverters, most of submarines adopt an eletric propulsion system. Although PMPM(Permanent Magnet Propulsion Motor) propulsion system has relatively higher power, energy conversion efficiency and smaller volume than engine propulsion system, it also produces large amount of heat due to current flowing inside motor coils and change of magnetic field induced by iron core. The produced heat in stator and inverter largely affects motor efficiency and bearing lubrication and causes thermal aging while the system is on operation. So, we analyze the existing cooling system and submarine ESS (Energy Saving System) cooling system whose power consumption is reduced. HILS(Hardware In the Loop System) technique is used for the modelling of the submarine cooling system. To confirm the ESS cooling system characteristic, HILS is simulated using LabVIEW with hardware. As a result, the ESS cooling system has the characteristic of better temperature stability and less power consumption than the existing one.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.32-36
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• 2003

This paper deals with a theoretical method for the design of a biased asymmetric preswirl stator propulsion system which has been used to increase efficiency by the recovery of a propeller slipstream rotational energy by the counter rotating flow of a stator. In the case of full slow-speed ship, the upward flow is generated at the propeller plane by the after body hull form. The generated upward flow cancells the rotating flow of the propeller at the starboard part while it increases at port part. A biased asymmetric preswirl stator propulsion system consists of three blades at the port and one blade at the starboard which can recover the biased rotating flow effectively. This paper provides the design concept which gives more simple and a high degree of efficiency. The model tests for the designed compound propulsion system will be carried out later.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2323-2328
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• 2011

There have been many changes in Subway train types since SeoulMetro opened the Line No.1 in 1974. Propulsion control device has changed many times following the generations of control method from resistance control method which uses large resistor for the traction motor control to chopping control which uses power semiconductors and finally to inverter control. Railroad vehicle propulsion control device refers to devices such as converter/inverter which supply power for subway operation, power conversion equipment like small switching-mode power supply and traction motor. In this paper, we will analyze every part of railroad vehicle propulsion control device of SeoulMetro so we can find problems in the subway operation. And we will present propulsion control device model which makes minimized failures, efficient maintenance possible when replacing railroad vehicle later. By doing this, we hope to ensure stability and improve energy efficiency to the top.