• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.153-156
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• 2008

Ignition and combustion performance of a gas-turbine engine were changed by various high-altitude condition. A goal of this study is to make the small test facility to simulate high-altitude condition. To perform the low pressure condition, a diffuser was used in various diffuser front of primary nozzle pressure. To perform the low temperature, heat exchanger was used in various mixture ratio of cryogenic air and ambient temperature air. The experimental result shows that high-altitude conditions can be controled by diffuser front of primary nozzle pressure and mixture ratio of cryogenic air and ambient temperature air.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.3
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• pp.73-82
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• 2015

A high altitude test facility which includes supersonic diffuser and ejector has been developed to simulate atmospheric pressure at 25 km using a 500 N class small scale liquid rocket engine. Also high altitude simulation test for the small scale liquid rocket engine was performed to verify the facility's performance. The experimental facility consists of high altitude simulation device, propellants supply system and coolant supply system. Low pressure condition corresponding to about 27 km(0.021 bar) altitude atmosphere was successfully simulated and a small scale liquid rocket engine thrust level was confirmed at the simulated condition by the high altitude test facility verification test.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.3
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• pp.61-68
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• 2010

A small high altitude test facility has been developed to investigate ignition performance of a small gas-turbine combustor under high altitude conditions. Supersonic diffusers and a heat exchanger were used to perform a low pressure and a low temperature condition, respectively. Experimental results showed that the low pressure environment could be controlled by upstream pressure of primary nozzle flow and low temperature environment by mixture ratio of cooled air and ambient air. Ignition performance tests were performed to verify the performance of the facility under simulated high altitude conditions. Conclusively, it was proven that the test facility could be used for ignition performance test of a small gas-turbine combustor under high altitude condition of approximately 6,100m.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.23-26
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• 2007

A preliminary， study of low temperature condition was performed to simulate high altitude condition. The mixed air temperature were investigated at various condition by experiments using cryogenic air by heat exchanger and normal temperature air. An experimental setup was constructed to simulate low temperature condition with liquid nitrogen. To control mass flow rate, orifice and pressure regulators were used. The experimental results show that the mixed air temperature increases linearly with mass flow rate of normal temperature air. Therefore it can be help to simulate a low temperature condition of high altitude.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.442-447
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• 2008

A numerical analysis has been conducted to investigate and characterize the unsteadiness of flow structure and oscillatory vacuum pressure inside of a supersonic diffuser equipped to simulate the high-altitude rocket test on the ground. A physical model of concern includes a rocket motor, a vacuum chamber, and a diffuser, which have axisymmetric configurations, using nitrogen gas as a driving fluid. Emphasis is placed on investigating physical phenomena of very complex and oscillatory flow evolutions in the diffuser operating at very close to the starting condition, i.e. minimum starting condition, which is one of major important parameters in diffuser design points of view.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.309-312
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• 2005

High altitude ignition test was performed to understand high altitude ignition characteristics of slinger combustor. To verify ignition limits, test was carried out with variation of altitude and fuel nozzle rotational speed using AETF(Altitude Engine Test Facility) in KARI(Korea Aerospace Research Institute). From the result, the effect of major factors which affect on ignition characteristics was observed. The reduction of ignition limit with increasing altitude and expansion of ignition limit with increasing rotational speed of fuel nozzle was verified. Also minimum rotational speed of fuel nozzle at high altitude must be greater than that of seal level condition.

• Journal of Astronomy and Space Sciences
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• v.27 no.3
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• pp.205-212
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• 2010

To better understand the physical processes that maintain the high-latitude lower thermospheric dynamics, we have identified relative contributions of the momentum forcing and the heating to the high-latitude lower thermospheric winds depending on the interplanetary magnetic field (IMF) and altitude. For this study, we performed a term analysis of the potential vorticity equation for the high-latitude neutral wind field in the lower thermosphere during the southern summertime for different IMF conditions, with the aid of the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM). Difference potential vorticity forcing and heating terms, obtained by subtracting values with zero IMF from those with non-zero IMF, are influenced by the IMF conditions. The difference forcing is more significant for strong IMF $B_y$ condition than for strong IMF $B_z$ condition. For negative or positive $B_y$ conditions, the difference forcings in the polar cap are larger by a factor of about 2 than those in the auroral region. The difference heating is the most significant for negative IMF $B_z$ condition, and the difference heatings in the auroral region are larger by a factor of about 1.5 than those in the polar cap region. The magnitudes of the difference forcing and heating decrease rapidly with descending altitudes. It is confirmed that the contribution of the forcing to the high-latitude lower thermospheric dynamics is stronger than the contribution of the heating to it. Especially, it is obvious that the contribution of the forcing to the dynamics is much larger in the polar cap region than in the auroral region and at higher altitude than at lower altitude. It is evident that when $B_z$ is negative condition the contribution of the forcing is the lowest and the contribution of the heating is the highest among the different IMF conditions.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.707-710
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• 2008

The method suggested in this thesis is the safe and economic method when testing rocket engine because ground test facility copies high altitude. We have decided to use the schematic of testing facility based on already known design method and test result, and we have decided the test condition for ground firing test of solid fuel. In addition the pressure of nozzle exit area is 0.1bar, we have designed the testing facility structure to test in this condition. Moreover, we have designed to reduce the accident probability.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.647-650
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• 2017

As the necessity of development of supersonic vehicle increases, securing an aerodynamic data from low to high altitude is requested for flying vehicles crusing in various high-tech environment. Therefore our research team built equipment by improving heating device of Model Aerodynamic Facility(MAF) of Konkuk University to simualte a real gas environment. Guided weapon system and temperature and velocity distribution according to the flow that is produced from the pier of supersonic vehicle is planned to be researched by using this equipment.

• Journal of IKEEE
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• v.22 no.3
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• pp.747-753
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• 2018

Currently, many companies have succeeded in logistics delivery experiments utilizing drone and report it. When a drone is used commercially, long-term flight is an important performance that a drone should have. However, unlike vehicles operated on the ground, drone is a vehicle that continues to consume energy when maintaining the current altitude or moving to the destination. Therefore, the drones can fly for a long time as the capacity of the battery is large, but the batteries with large capacity are restricted by heavy weight and it acts as a limiting factor in a commercial use. To address this issue, we attempt to compare how far we can fly than forward flight based on the flight pattern with the same energy consumption condition. In this paper, the comparison of energy consumption was performed in three flight pattern, forward flight without altitude change and forward flight with altitude change, by computer simulation and it shows the increasing of flight distances when the quadrotor fly with altitude change from high altitude to low altitude.