• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.4
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• pp.10-20
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• 2022

The performance analysis test of the scramjet engine intake was conducted under the Mach 5 condition of the scramjet engine test facility, a free-jet ground test facility of the Korea Aerospace Research Institute. A pitot/static pressure rake installed at the rear of the isolator was designed and manufactured to measure the total pressure recovery rate and mass capture ratio, which are typical performance factors of the scramjet engine intake. The effect of the rake mounted at the rear of the isolator on the intake, the performance analysis measured by the rake, and the change in wall static pressure distribution according to the angle of attack were performed. Finally, the point at which the intake unstart occurred was confirmed by using the rear back pressure adjusting device, which simulates pressure rise in the combustor, and the results are summarized in this paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.4
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• pp.315-322
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• 2009

In the conventional boost converter, the actual duty cycle is limited as the output voltage increases due to increased voltage and current stress of the switch and diode and voltage surge caused by diode reverse recovery. In this paper a new non-isolated boost converter suitable for high gain applications is proposed. The proposed converter has voltage gain of around 6 when the duty cycle is 0.5. Since ZVS is achieved under CCM, the proposed converter has wide ZVS range. Also, voltage ratings of switch and diode are the same as one third of output voltage, and ratings of input and output passive components are reduced due to the interleaving. In addition voltage surge caused by diode reverse recovery is negligible due to ZCS turn-off of diodes. Operating principle of the proposed converter is described and validated through theoretical analysis, simulation and experiment.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.16-27
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• 2020

For the operation of the scramjet engine in the wide flight range, the design of the inlet must show stable performance in various flight conditions. In this study, the design methods of a 2D fixed inlet for stable performance in wide flight ranges of Mach number 4 to 6 and angle -6° to 6°, is performed. After proposing the design method and design focus, performance prediction and analysis were performed by various initial compression angles and design Mach numbers, which are essential design factors in total pressure recovery and inlet capture area ratio in the wide flight range. Based on the analysis results, we present the selection criteria for the two main design elements to represent stable performance in the wide flight range.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.297-308
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• 2022

Most air-breathing aircraft operated in the hypersonic region are equipped with a scramjet engine. In a scramjet engine, a shock wave generated at an inlet acts as a compressor for a general gas turbine engine instead, so total pressure loss caused by the shock wave is considered very important. In this study, to minimize total pressure loss, a method of designing an external compression inlet using isentropic compression surface was proposed, and an external compression inlet with 3-deflection angles and Busemann inlet were designed under the same conditions. After that, through computational analysis, the performance characteristics at off-design conditions were compared. Each inlet shape was truncated according to the length of the 3-ramp external compression inlet, and the boundary layer correction was performed. The isentropic external compression inlet showed superior performance at the design point, but under the off-design conditions, its performance was degraded compared to the 3-ramp external compression inlet.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.61-70
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• 2006

A Supersonic air intake model was designed for the high performance ramjet and dual-mode scramjet engine to operate at Mach 4 flight condition. The air intake was tested in the blowdown-type wind tunnel of Kyushu University to identify the internal flow characteristics corresponding to the flight parameters such as the back pressure, angle of attack and angle of yaw. Flow visualization was achieved by the Schlieren and oil flow visualization techniques. The intake performance was analyzed quantitatively based on the surface pressure and total Pressure measurements. The experimental results were compared with the computational fluid dynamics results. The present study exhibits the fundamental but rarely found experimental results of the high Mach number supersonic air intake.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.207-210
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• 2008

In this study, one type of ramjet intake were designed for the flight condition of Mach number 4 and numerical analysis was performed. In order to widen the flight envelope range (Mach number $2{\sim}6$), movable intake concept was applied. The central body was designed so that the capture area ratio which is one of most important factors of ramjet intake design could be adjusted. And various types of cowl and movable insert part of shell were designed in order to control throat area which could increase total pressure recovery. The numerical results showed that the designed ramjet intake could be applied in various flights Mach number.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.992-995
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• 2011

A study on the performance design schemes of the supersonic air intakes applied to the supersonic air-breathing propulsion system(Ramjet/Scramjet) was conducted and for two kinds of air intakes, the preliminary configuration designs and the performance analysis models were established. For axisymmetric conical air intake and two dimensional rectangular air intake, the performance effects were assessed according to compression angles and shock wave numbers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.393-396
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• 2006

This paper presents the characteristics of the performance parameters of dual mode(ramjet-scramjet combined) engine, inlet and combustor for wide range of flight Mach number, resulted from the analysis of its operating limitations. The transitional-critical flight Mach number from ramjet to scramjet and the performance of two types of combustors, such as constant pressure- and constant area- combustor, are conceptually evaluated.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.114-121
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• 2011

This paper proposes a soft-switching interleaved boost converter which is suitable for high step-up and high power applications. Compared to the conventional boost converter the proposed converter can achieve approximately doubled voltage gain using the same duty cycle. The voltage ratings of the switch and diode are reduced to half, which result in the use of devices with lower $R_{DS(ON)}$ and on drop leading to reduced conduction losses. Also, voltage ratings of the passive components are reduced, and therefore the total energy volume is reduced to half. Further, the switch is turned on with ZVS in the CCM operation, and the diode is turned off with ZCS which results in negligible surge caused by diode reverse recovery leading to reduced switching losses. The validity of the proposed converter is proved through a 2kW prototype.

• Journal of IKEEE
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• v.23 no.3
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• pp.962-970
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• 2019

In this paper, the non-isolation, high-efficiency and high-voltage-output DC-DC converter using the self-driven synchronous switch is proposed. The proposed converter achieves high-voltage-output by applying a tapped inductor to the conventional boost DC-DC converter structure, and it reduces the voltage stress of main switch applying the lossless capacitor-diode (LCD) snubber to the switch. And the proposed converter applies the synchronous switch instead of the diode to the output part, and thus it resolves the reverse recovery problem and achieves high-efficiency. The synchronous switch of proposed converter uses the self-driven method and has a simple structure. In this paper, the operation principle of proposed converter is explained, and then, a design example of the converter prototype is presented. And the characteristics of the proposed converter are shown through experimental results of the prototype made with the designed circuit parameters.