• Journal of the Korean Society of Propulsion Engineers
• /
• v.5 no.3
• /
• pp.87-99
• /
• 2001

Technical status and prospect of the subsonic airbreathing propulsion system composed of jet engine fuel feeding system and air intake for missile application is described herein, including analysis of some present airbreathing missiles. Comprehension on this can be applicable both to blow deeply about the same type missiles and to get some basic idea of unmanned air vehicle's and light aircraft's propulsion system.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.12
• /
• pp.1031-1038
• /
• 2017

In order to improve the performance of the air breathing engines, it is important to maximize the total pressure recovery through air intake. In this study, we investigated whether the Oswatitsch method, which guarantees the maximum pressure recovery for supersonic intake, is effective at hypersonic speed by compressing the intake air with the same intensity at each ramp. The non-linearity of the shock wave normal Mach number at each ramp stage was analyzed by comparing the compression ramp angle and the number of ramp to the inflow Mach number in terms of compressible thermodynamics and the operation limits of the inlet. Based on this analysis, the Oswaitisch technique yields valid conditions not only in supersonic but also hypersonic flight regime.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.241-245
• /
• 2011

In an engine test, data are collected in a form of a time series. Usually only the time average of a time series is interesting to engineers while its stochastic fluctuation is being ignored. In this paper, we collect pressure and fuel flux data from an air-breathing engine test and analyze their fluctuations using the multiscale sample entropy analysis, which is suggested as a measure of the complexity of a time series. It is shown that different physical quantities indeed have different complexities at each timescales, suggesting a possibility of an instantaneous tool which evaluates the engine test.

• Fire Science and Engineering
• /
• v.24 no.6
• /
• pp.98-103
• /
• 2010

A series of fire experiments have been performed to examine the measurement bias of the bare bead thermocouple widely used in fire testing and analyze the measurement bias of bare bead thermocouple comparing with the measured temperature using the aspirated thermocouple. The measured temperature of the bare bead thermocouple was lower than that of the aspirated thermocouple in the hot upper layer while it showed opposite trends in the upper layer. Also, the bare bead thermocouple showed higher measurement bias in the lower layer rather than upper layer in the compartment fire. The maximum relative percentage error of the bare bead thermocouple against the aspirated thermocouple reached 250% in the present study. The present study points out the need of correction process of the measured temperature by bare bead thermocouple for improving the reliability of the fire tests.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.579-583
• /
• 2011

The component based propulsion modeling and simulation of an air-breathing engine such as ramjet and scramjet is studied. The simulation model has been realized considering the characteristics of the air-breathing engine which is composed of air intake, combustor and nozzle including engine controller and fuel supply system. To estimate the engine performance and to verify the engine controller, real time based Hardware in the Loop System simulating actual environment is constructed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2003.05a
• /
• pp.59-63
• /
• 2003

This paper describes the conceptual design method of subscale direct-connect test facility for liquid fuel ramjet combustion study and preliminary analysis of test results. The measured pressure signal represents the successful operation of the test facility. The pressure oscillation in combustion chamber shows the dominant frequency of 190Hz, relatively very low frequency to 1L acoustic mode (1200Hz) based on the length of combustor. It is suspected that there were several driving sources, which are vortex street at backward step of combustor, inlet resonance induced by the long length of unchecked inlet, and/or combustor configuration with optical window.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.18 no.6
• /
• pp.1-10
• /
• 2014

The optimal method to intuitively and systematical design hypersonic intakes is reported. In Mach 7 flow condition, the hypersonic intake model designed by theoretical approach is corrected by CFD(Computational Fluid Dynamics) analysis based on viscous flow condition, leading to the optimum hypersonic intake model. For performance comparison with CFD analysis, the double ramp intake is superior to the single ramp intake. Furthermore, in the off-design condition, the performance of the designed hypersonic intake is little degraded.

• Korean Journal of Construction Engineering and Management
• /
• v.24 no.4
• /
• pp.3-13
• /
• 2023

The purpose of this study is to compare and analyze the performance and work productivity of wet type pavement cutters and sludge suction type pavement cutters (hereinafter referred to as automatic pavement cutters) developed to reduce scattering dust. We first investigated the development status of wet type manual pavement cutters that are mainly used in Korea and automatic pavement cutters, and analyzed the pavement cutting work in detail. And the standard cutting performance was derived by measuring the cutting time by depth by applying the two equipment to the test bed under the same conditions. However, there is a limitation that the data measured in the test bed does not reflect the various variables of the actual pavement cutting site. Therefore, in this study, data was collected through field surveys, and the correlation between cutting distance and time was analyzed, and then a model for calculating the productivity of pavement cutters was presented through simple regression analysis. As a result of comparative analysis of the values derived from the regression equation with the standard cutting performance derived from the test bed, the cutting performance derived through the regression equation showed a similar trend to the standard cutting performance. Finally, we verified the usability of the automated pavement cutter developed by qualitatively analyzing three tasks that are difficult to measure quantitatively but affect productivity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.11a
• /
• pp.331-335
• /
• 2006

Theoretically, stable operations of an inlet are achieved at the design condition. However, at off-design conditions supersonic inlets often encounter the problem of aerodynamic instability, called inlet buzz. During inlet buzz, supersonic inlets exhibit considerable oscillation of the shock system in front of the inlet and corresponding large pressure fluctuations downstream. This phenomenon results in decrease of engine performance. An experimental and numerical study was conducted to investigate the phenomenon of supersonic inlet buzz on a generic, axisymmetric, external-compression inlet with a single-surface center-body. This study suggest that intermittent buzz exist and the frequency become to be large as increasing the back pressure.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.19 no.3
• /
• pp.65-72
• /
• 2015

In present study, a supersonic inlet for dual mode ramjets or RBCC/TBCC engines with a wide range of flight Mach numbers is designed. A conical variable inlet configuration is chosen for the inlet design. Geometric relations with angles of compression cones and conical shock waves are used for the design of the inlet configuration. The performance of the supersonic inlet is confirmed by the numerical analysis. The capture area ratio is maintained around 100% from Mach 3 to 8 conditions.