• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.8
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• pp.671-678
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• 2018

Helicopter noise prediction is an essential process for developing low noise helicopter technology. In this paper, the noise prediction method is developed using the helicopter integrated performance analysis program CAMRAD-II and in-house noise analysis code. In addition, the analytical technique was verified by analyzing blade-vortex interaction noise, which is the biggest cause of helicopter noise. In order to predict the actual helicopter noise, the noise analysis was performed for the flyover and approach condition, which is the standard measurement condition of the International Civil Aviation Organization (ICAO). Finally, we confirmed the suitability of the analytical method through comparison and analysis with the flight test results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.71-74
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• 2012

Generally, tone noise is generated at the rotary wing and helicopter. BVI(Blade-Vortex Interaction) noise is one of the helicopter's tone noise. The BVI noise is governed by tip-vortex characteristics such as vortex size, strength and trajectory. To avoid BVI, many methods have been developed and proposed. In this paper, rotating blade with active tab was numerically investigated to reduce BVI noise. For flow and noise simulation, the lifting surface approach and the acoustic analogy were used. Using numerical methods, the noise directivity and maximum noise position were predicted.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.77-89
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• 2011

The vibration and noise reduction issue is very important in helicopter since the thrust and flight control force of helicopter are generated by rotating drive system. In past, there was a passive method to reduce vibration and noise to focus on specified frequency. Now, there are various active method to reduce vibration and noise due to technology development. This paper describes the worldwide technology trend of vibration and noise active control in helicopter. At introduction, generalmethod of vibration and noise reduction.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.70-74
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• 2009

The helicopter development technology is improved by the increasing of computing power and advanced test facilities. The increasing efficiency of fuel consuming by the developing of improved lift-to-drag rotor system is the major issue, the noise reduction for ecology(civil area) and increase of survivability to reduce noise detection(battlefield) also are important. This investigation shows the helicopter external noise flight test methods, conventional military helicopter's(UH-60) experimental results and the numerical modeling method for aero-acoustic of rotor blade and the result of CAA(Computational Aero-Acoustic) for main rotor blade.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.302-307
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• 2008

The development technology for the helicopter is improved by the increasing of computing power and advanced test facilities. The increasing efficiency of fuel consuming by the developing of improved lift-to-drag rotor system is the major issue, the noise reduction for ecology(civil area) and increase of survivability to reduce noise detection(battlefield) also are important. This investigation shows the classification of helicopter external noise and requirements, the noise flight test methods, the numerical modeling method for aero-acoustic of rotor blade and the result of CAA(Computational Aero-Acoustic) for main rotor blade.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.302-307
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• 2008

The development technology for the helicopter is improved by the increasing of computing power and advanced test facilities. The increasing efficiency of fuel consuming by the developing of improved lift-to-drag rotor system is the major issue, the noise reduction for ecology(civil area) and increase of survivability to reduce noise detection(battlefield) also are important. This investigation shows the classification of helicopter external noise and requirements, the noise flight test methods, the numerical modeling method for aero-acoustic of rotor blade and the result of CAA(Computational Aero-Acoustic) for main rotor blade.

• Journal of Aerospace System Engineering
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• v.1 no.1
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• pp.73-78
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• 2007

Self-noise from the rotor blade of the UH-1H Helicopter is obtained numerically by using the Brooks' empirical noise model. All of the five noise sources are compared with each other in frequency domain. From the calculated results the bluntness noise reveals dominant noise sources at small angel of attack, whereas the separation noise shows main noise term with gradually increasing angel of attack. From the results of two different tip Mach numbers with the change of angel of attack, the OASPLs at M = 0.8 show about 15dB larger than those at M = 0.4.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.325-329
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• 2003

Nowadays many peoples are using helicopter in various fields, not only military use but also common people applications such as air-measurement, photography, transportation of goods and persons, saving life and fire fighting etc. And it will be expected more popular than now. Most important part of helicopter to increasing performance and to reducing noise is rotor hub-system. Hub system consists of rotor-blade and rotor-hub. We participate to develop next-generation rotor hub system with elastomeric bearing, part of rotor hub. In this paper we introduce about the role and shape of elastomeric bearing in next-generation helicopter hub system. Then we study about bearing-material requirements and measuring methods. Finally we represent some experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.690-695
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• 2006

This paper described the Performance test and sound characteristics of helicopter 'Tail-Fan' anti-torque system. In this research, Korea Aerospace Research Institute(KARI) developed 'Tail-Fan' anti-torque system for a helicopter and carried out performance and sound capturing tests of even and uneven tail fans. The performance test is carried out and the noise signals which are generated during the test are saved with microphones at the same time. The performance test's results meet the design requirements. Tone-corrected perceived noise level is reduced by replacing the even product with the uneven one.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.857-863
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• 2006

This paper described the performance test and sound characteristics of helicopter 'Tail-Fan' anti-torque system. In this research, Korea Aerospace Research Institute(KARI) developed 'Tail-Fan' anti-torque system for a helicopter and carried out performance and sound capturing tests of even and uneven tail fans. The performance test is carried out and the noise signals which are generated during the test are saved with microphones at the same time. The performance test's results meet the design requirements. Tone-corrected perceived noise level is reduced by replacing the even product with the uneven one.