• Journal of Advanced Navigation Technology
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• v.3 no.2
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• pp.97-107
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• 1999

Passive sensors such as Laser Range Finder(LRF) and Forward Looking Infrared(FLIR) camera frequently used for tracking aircraft landing produce the measurements of elevation angle contaminated by large noise due to the exhaust plume disturbance. This results in poor tracking performance if the extended Kalman filter is used for estimation of the range and elevation which are corrupted by the non-Gaussian noise such as plume disturbance. In this paper, an adaptive estimation filter and the extended Kalman filter is combined to produce a combination-type filter. In this approach the adaptive filter is used for the plume-type disturbance noise and the extended Kalman filter is utilized for the measurement of Gaussian type. The proposed combination filter is effective for the trajectory estimation of landing aircraft under the influence of unknown bias and numerical simulations illustrate the performance of the proposed filter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.568-575
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• 2016

For the combat survivability, an infrared signature emitted from aircraft is needed to be predicted and analyzed. In this study, we studied the infrared signature from the exhaust plume from the viewpoint of Infrared(IR) detector. The Line-By-Line method using the radiation database is used for radiative property, and radiative intensity analysis is conducted along 1-D line of sight based on the radiative property. The numerical thermo-fluid field for the plume is conducted by ANSYS FLUENT, while setting the lines of sight having the different detection angle on the thermo-fluid field. We found the high IR signature on the line of sight passing through the locally high temperature region of the plume inside, and the strongest signature from the line of sight toward the nozzle surface. Based on this, it confirms the influence of the surface radiative emission on the infrared signature.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.640-647
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• 2014

Infrared signature of aircraft exhaust plume is the critical factor for aircraft survivability. To improve the military aircraft survivability, the accurate prediction of infrared signature for the propulsion system is needed. The numerical analysis of thermal fluid field for nozzle inflow, free stream flow, and plume region is conducted by using the in-house code. Weighted Sum of Gray Gases Model based on Narrow Band with regrouping is adopted to calculate the spectral infrared signature emitted from aircraft exhaust plume. The accuracy and reliability of the developed code are validated in the one-dimensional band model. It is found that the infrared radiant intensity is relatively more strong in the plume through the analysis, the results show the different characteristic of the spectral infrared signature along the temperature, the partial pressure, and the species distribution. The continuous spectral radiant intensity is shown near the nozzle exit due to the emission from the nozzle wall.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.96-101
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• 2015

This study regards distributions of flow in the ventilation system used in the kitchen hood in a ship. In this study, for describing the flow in the ventilation system, three-dimensional steady-state turbulence was assumed for the governing equation. When the plume was formed, three gases, CO, CO2, and HCL, in the flow field of the hood were considered as the plume, and it was assumed that the sum of concentrations of the gases was 100%. As a result, it could be confirmed that the plume was smoothly discharged when the flow rate of the supply was ten times lower than that of the exhaust.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.4
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• pp.22-29
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• 1997

This paper presents results on dynamic analysis of the missile initial motion arising from the missile detent force. Using ADAMS (Automatic Dynamic Analysis of Mechanical Syatem) software, a non- linear46-DOF (Degree of Freedom) model is developed for the launcher system including missile and lunch tube contact problem. From the dynamic analysis, it is found that initial angular velocity of the missile incre- ases when the missile detent force increases and also when rocket exhaust plume is taken into account. To achieve the missile launching stability, it needs to reduce the missile initial detent force and exhaust plume area of the lancher. Results of the dynamic analysis on the system natural frequency agree well with those obtained from experimental modal tests. The overall results suggest that the proposed method is a useful tool for prediction of initial missile stability as well as design of the missile launcher system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1017-1022
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• 1996

This paper presents results of dynamic analysis of the missile initial motion arising from the missile detent force. Using ADAMS (Automatic Dynamic Analysis of Mechanical System) software, a non-linear 46-DOF (Degree of Freedom) model is developed for the launcher system including missile and launch tube contact problem. From the dynamic analysis, it is found that initial angular velocity of the missile increases when the missile detent force increases (more than 18 g) and also rocket exhaust plume is taken into account. To achieve the missile launching s ability, it needs to reduce the missile initial detent force and exhaust plume area of the launcher. Results of the dynamic analysis on the system natural frequency agree well with those obtained from experimental modal tests. The overall results suggest that the proposed method is a useful tool for prediction of initial missile stability as well as d :sign of the missile launcher system.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.85-91
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• 2005

Radiative heating of a liquid rocket base plane due to plume emission is numerically investigated. Calculation of flow and temperature fields around rocket nozzle precedes and thereby realistic plume shape and temperature distribution inside the plume are obtained. Based on the calculated temperature field, radiative transfer equation is solved by discrete ordinate method. With the sample rocket plume, the averaged radiative heat flux reaching the base plane is calculated about 5 kw/m$^{2}$ at the flight altitude of 10.9 km. This value is small compared with radiative heat flux caused by constant-temperature (1500 K) plume emission, but it is not negligibly small. At higher. altitude (29.8km), view factor between the base plane and the exhaust plume is increased due to the increased expansion angle of the plume. Nevertheless, the radiative heating disappears since the base plane is heated to high temperature (above 1000 K due to convective heat transfer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.266-271
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• 2008

Generation mechanisms of pressure waves from the H-IIA launch vehicle are analyzed numerically. The Mach wave radiated downstream from wavy shearlayer of supersonic exhaust plume is revealed to be the dominant noise source. Reflecting from the constructions of the launch-pad, the Mach wave turns to propagate to the vehicles. It was also found that the fluctuating supersonic plume entering into the flame duct is the dominant noise source that appears in the flame duct. Then, the pressure wave propagates through the flame duct and is ejected outside to the vehicle.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.126-134
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• 2012

The Single Species, Unreacted Flow Model which is effectively applicable on the computational analysis of rocket exhaust flow is introduced in this paper. The basic concept of this model had been originated from chemically frozen analysis of hot air but it was complemented by compensating molecular weight and specific heat which was obtained CEA code analysis of exhaust plume. Comparing single species, unreacted model with the finite chemistry model, unreacted model can reduce calculation time to 1/5 while it makes similar simulation results.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.54-61
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• 2014

In this study, a plume exhausted from rocket nozzle is investigated by using an unstructured 2-dimensional axisymmetirc DSMC code at various altitude. The small back-pressure to total-pressure ratio($P_b/P_o$) and large $P_b/P_o$ represent low and high altitude condition, respectively. At low altitude, the plume shows a typical complicated structure (e.g. Mach disk) of underexpanded jet while the high altitude plume experiences plain expansion. The various features of exhaust plume is discussed including density, translational/rotational temperature, Mach number and Knudsen number. The results shows that even at 20 km altitude where the freestream Knudsen number is small as $1.5{\times}10^{-5}$, the transitional and rarefied flow regimes can occur locally within the plume. It confirms the necessity of DSMC computation at low altitude.