• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.4
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• pp.253-260
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• 2013

Ice accretions on the surface around a rotorcraft air intake can deteriorate the safety of rotorcraft due to the engine performance degradation. The computational simulation based on modern CFD methods can be considered extremely valuable in analyzing icing effects before exact but very expensive icing wind tunnel or in-flight tests are conducted. In this study the range and amount of ice on the surface of anti-icing equipment are investigated for heat-on and heat-off modes. It is demonstrated through the computational prediction and the icing wind tunnel test that the maximum mass and height of ice of heat-on mode are reduced about 80% in comparison with those of heat-off mode.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.978-983
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• 2015

A study on the speed limit and sizing of auxiliary fixed-wing of compound gyroplane was performed. The performance of the plane that uses the same rotor system and power of BO-105 helicopter was compared with that of BO-105 helicopter. The wing area which is used to compensate in lift, was calculated considering the aerodynamic characteristics and lift sharing ratio of the rotor. Achievable flight speeds were observed for two types of fuselage; BO-105 and streamlined bodies. The study showed that the autorotating rotor can share 1/2 of lift at high speed and the parasite power of compound gyroplane having streamlined body and small wing can be minimized, accordingly it can fly faster than helicopter with airspeed more than twice.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.3
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• pp.44-52
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• 2004

In this study, a component map generation method using experimental data and the genetic algorithms are newly proposed. In order to generate the performance map for components of this engine, after obtaining engine performance data through many experimental tests, and then the third order equations which have relationships the mass flow function the pressure ratio and the isentropic efficiency as to the engine rotational speed were derived by using the genetic algorithms. A steady-state performance analysis was performed with the generated maps of the compressor by the commercial gas turbine performance analysis program GASTURB. In comparison, it was found that the component maps can be generated from the experimental test data by using the genetic algorithms, and it was confirmed that the analysis results using the generated maps were very similar to those using the scaled maps from the GASTURB.

• Journal of KSNVE
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• v.11 no.3
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• pp.461-470
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• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.20-26
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• 2000

In this experimental study, we examined gas engine characteristics of a small high-speed engine in various ways. And we studied performance of natural gas, hydrogen gas and gasoline fuel engines, as emission characteristics and process of combustion. For the purpose of preventing back-fire occurred in case of high-speed and high load in hydrogen engine, we controlled air quantity by installing throttle valve in gas fuel engine. We performed experiment by mixing nitrogen to hydrogen fuel. As a result, we could find out characteristics which of a high speed small engine by applying gas fuels.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.41-47
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• 2011

Turbopump, which is a part of 75 ton open cycle liquid rocket engine has a super sonic impulse turbine. This paper investigated the leading edge thickness effect on the turbine performance experimently. Two rotors were tested with the different leading edge thickness. The ratios (rotor thickness to Pitch) are 1.9 and 1.4 times to 30 ton turbine rotor. As a result, a rotor with 1.4 times ratio had a 1.5% higher efficiency gain than a rotor with 1.9 times ratio. The pressure ratio with the maximum efficiency on the same rotational speed was increased to the full expansion ratio of nozzle.

• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.8-13
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• 2017

This study was performed to evaluate the turbine performance of a turbopump in the third stage engine of the Korea Space Launch Vehicle-II. The turbine is a supersonic impulse type with a single rotor. One nozzle is for starting and four remaining nozzles are for steady operation. A similarity test was carried out in the high air test facilities at the Korea Aerospace Research Institute. Test results showed that turbine efficiency changed much more from rotational speed variations than by pressure ratio variations. These results showed characteristics similar to other supersonic impulse turbines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.149-152
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• 2010

It was investigated that effect of the supersonic impulse turbine rotor leading edge thickness which was the part of 75 ton open cycle liquid rocket engine turbopump. The test for turbine was performed that the rotor thickness to pitch ratio was 1.9 and 1.4 to 30 ton turbine. As a result of test, the rotor with lower thickness(1.4) had 1.5% efficiency gain to the higher thickness(1.9) and the pressure ratio with maximum efficiency was increased to the nozzle full expansion point.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.77-80
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• 2010

A series of hydraulic tests of a Lox pump are performed using water at a room temperature. According to the test results, the Lox pump satisfies its design requirement but both the head and the efficiency do not fully follow the conventional similarity rule. The deviation of the head from the rule is assumed to be due to the increased volute loss at high rotational speed. Furthermore, it is found that when the pump rotates with the flow ratio less then the design requirement the leakage flowrate seems to be increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.299-306
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• 2015

Turbocharged gasoline direct injection engine is one of promising technologies in the automotive industry. However, reduction in turbo-lag under transient operation is one of important challenging points to improve drivability. Engine transient performance was investigated in a 4-cylinder 2.0 L turbo-gasoline direct injection (T-GDI) engine using Inconel and TiAl (Titanium Aluminide alloy) turbine wheel turbochargers. The TiAl turbocharger performed superior transient boost pressure and torque rises under various engine transient operation conditions. These were mainly due to lower turbine rotational inertia of TiAl turbocharger. The Maximum boost pressure and torque build up were founded in 1500 rpm and 2000 rpm, instant load change from 20% to 100% of pedal position.