• Title/Summary/Keyword: 날개회전주파수

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직사각형 통에 설치된 축류 홴의 소음 특성

  • 최정명;구정호
    • Journal of KSNVE
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    • v.1 no.2
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    • pp.102-106
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    • 1991
  • 최근의 사회적 경제적인 급속한 발전에 따라 환경 소음에 대한 사람들의 관심도가 점차 증가되고 있다. 이로 인하여 사람들이 항상 접촉하게 되는 가전 제품 에 대한 소비자의 욕수도 제품의 성능적인면도 물론이지만 소음진동 및 디자인에 대하여도 지대한 관심이 모아지고 있다. 가전 제품에 있어서 주된 소음원은 홴 및 압축기 덮개의 진동등으로 파악할 수 있다. 특히, 홴은 냉각용, 송풍용으로서 거의 모든 가전제품에 쓰여지고 있다. 냉각용으로 사용되는 형식은 주로 축류 홴이다. 축류 홴은 다른 종류보다 소음이 크기 때문에, 저소음 축류 홴의 BPF(Blade Passing Frequency; 날개 통과 주파수)가 갖는 소음 특성을 연구하여야 한다. 이를 위해 축류 홴의 날개 갯수를 조절하면 설치된 통내에서의 BPF가 어떠한 형태로 변화하는가를 알아보고, 이에 따른 저소음화 대책을 검토하고자 한다. 홴은 그 덮개에 대하여 유량 및 소음에 관한 최적의 위치가 존재하는데, 문이 잠겨 있을 때에는 그 소음 레벨의 편차가 몹시 크게 된다. 한편 날개 갯수, 모터의 회전속도 및 통의 전달 함수 등을 감안하여 날개 통과 주파수(BPF)를 조정하면, 각종 가전 제품의 홴에 의한 방사를 저감시킬수 있다.

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The Noise Radiation Characteristics of Axial Fan by Experimental Method (실험적 방법에 의한 축류형 팬의 소음 방사 특성에 관한 연구)

  • 김동규;오재응
    • The Journal of the Acoustical Society of Korea
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    • v.11 no.1E
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    • pp.50-55
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    • 1992
  • 팬의 익면 통과 주파수 소음은 총괄 소음 스펙트럼중에서 가장 명백한 성분이다. 그 소리는 일 반적으로 가장 불쾌한 성분이므로 저감이 요구된다. 따라서 그 소음치를 저감시키기 위해서는 정확한 축류형 팬의 소음원과 소음 방사 특성 규명이 요구된다. 본 연구에서는 푹류형 팬의 소음원과 소음 방 사 특성을 정의하였다. 음압 및 음향인텐시티를 이용한 음원 해석에서, 광센서를 이용한 축류형 팬의 동 기화가 수행되었고, 팬 날개에서의정확한 소음원의 위치를 결정하기 위해 Recording time의 결정이 제 안되었다. 팬 회전시, 소음원의 위치는 각 날개의 후단과 그 다음 날개의 선단사이에 각각 존재한다. 지 향성을 통하여 축류형 팬의 소음 방사 형태를 결정하였고, 벡터 에너지 흐름도로 음의 흐름을 가시화하 였다. 팬 익면에서의 회전 진동특성을 스트레인 게이지에 의하여 규명하였고, 또한 구조진동음의 음으로 의 기여도를 측정하였다. 또한 압전필름에 의한 팬 익면에서의 정압측정 가능성이 제시되었다.

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Investigation on Forced Vibration Behavior of Composite Main Wing Structure of A Small Scale WIG Craft Excited by Engine and Propeller (엔진 및 프로펠러에 의해 가진되는 소형 위그선 복합재 주날개의 진동 거동 해석)

  • Kong, Chang-Duck;Yoon, Jae-Huy;Park, Hyun-Bum
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.11
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    • pp.1028-1035
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    • 2007
  • this study, forced vibration analysis was performed on the composite main wing structure of a small scale WIG craft which is equipped two-stroke pusher type reciprocating engine. The structural vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the H-mode(horizontal mode), the V-mode(vertical mode) and the X-mode(twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the L-mode(longitudinal mode) with the oscillating propeller thrust which occurs.

Investigation on Forced Vibration Behavior of Composite Main Wing Structure Excited by Engine and Propeller (엔진 및 프로펠러 가진에 의한 위그선 복합재 날개 진동 해석)

  • Kong, Chang-Duk;Yoon, Jae-Huy;Park, Hyun-Bum
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.04a
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    • pp.217-221
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    • 2007
  • In this study, forced vibrations analysis was performed for main wing of small scale WIG vehicle which is equipped two-stroke pusher type propeller engine, in terms of structural. for the frequency response analysis, excitations were assumed by H-mode(Horizontal mode), X-mode(Twisted mode) which is main vibration mode of engine, and for the transient response analysis, excitations were assumed by L-mode(Longitudinal mode) with propeller thrust which is occurred when it revolution.

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Analysis of Micro-Doppler Signatures from Rotating Propellers Using Modified HHT Method (수정된 HHT 기법을 이용하여 회전하는 프로펠러 날개에 의한 마이크로 도플러 신호의 해석)

  • Park, Ji-Hoon;Choi, Ik-Hwan;Myung, Noh-Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.9
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    • pp.1100-1106
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    • 2012
  • This paper has presented the analysis of the micro-Doppler signatures scattered from the blades of the rotating propeller using the modified HHT method, one of the joint time-frequency analysis methods. The field scattered from the blade edge of the propeller was calculated using equivalent current method(ECM). After the acquisition of the scattered field data in the time domain, the modified HHT method was applied to analyze the micro-Doppler signature. The analysis results showed not only a good agreement with the realistic dynamic characteristic of the blade but also sinusoidally varing characteristics of the micro-Doppler signatures generated from rotating objects. It could be concluded that the joint time-frequency analysis via the modified HHT provided the discriminative characteristics for recognizing a small aircraft target with small RCS value.

High Frequency Signal Analysis of LOx Pump for Liquid Rocket Engine under Cavitating Condition (캐비테이션 환경에서의 액체로켓엔진용 산화제펌프의 고주파 신호 분석)

  • Kim, Dae-Jin;Kang, Byung Yun;Choi, Chang-Ho;Bae, Joon-Hwan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.4
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    • pp.61-67
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    • 2018
  • High-frequency signals are analyzed at the inlet/outlet pipeline and pump casing during cavitation tests of the LOx pump for liquid rocket engines. Root-mean square values of all data are investigated with respect to cavitation number. The values of synchronous, harmonic, and cavitation instability frequencies are also calculated. Pressure pulsations of the inlet and outlet pipelines are affected by cavitation instabilities. The 3x component (i.e., the blade-passing frequency of the inducer) is predominant in the outlet pulsation sensor. This seems to be related to the fact that the number of impeller blades is a multiple of the number of the inducer blades. The cavitation instability is also measured at the accelerometer of the pump casing.

Theoretical Prediction of Noise Generated by Unsteady Loading of Marine Propellers (프로펠러의 비정상하중에 의해 발생하는 소음의 이론적 추정)

  • Chang-Sup Lee;Chung-Ho Cho
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.3
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    • pp.29-40
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    • 1999
  • A numerical method in frequency domain for the analysis of the acoustic wave equation governing the sound field generated by a non-cavitating propeller under a steady of unsteady loading condition is developed. Theory shows that only multiples of the blade passage frequency exist and that the wave number consists of the frequency component due to the nonuniformity of the wake and the Doppler effect originated from the rotation of the blades. Correlation with experiments for a two bladed propeller, designed to be load-free at a particular advance speed, indicate that the thickness effect can be significant in steady case, but can be negligible compared to the unsteady loading effect.

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Study on Forced Vibration Behavior of WIG Vehicle Main Wing Structure Excited by Propulsion System (프로펠러 엔진에 의해 가진되는 소형 위그선 주날개의 진동 거동 해석에 관한 연구)

  • Kong, Chang-Duk;Yoon, Jae-Huy;Park, Hyun-Bum
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.7-12
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    • 2007
  • Previously study on structural design of the main wing of the twenty-seat class WIG (Wing in Ground Effect) craft. In the final design, three spars construction was selected for safety in the critical flight load, and the Carbon-Epoxy material was selected for lightness and structural stability. In this study, the forced vibration analysis was performed on the composite main wing structure of the twenty-seat class WIG craft with two-stroke pusher type reciprocating engine. The vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the Y-mode (lateral mode), the Z-mode (vertical mode) and the $M_{xyz}$-mode (twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the X-mode (longitudinal mode) with the oscillating propeller thrust which occurs in operation.

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Rotating Frequency Analysis of a Helicopter Rotor Blade with Swpt Tips (후퇴각 날개끝이 있는 헬리콥터 로터깃의 회전주파수 해석)

  • ;Yang, Wei Dong
    • Journal of KSNVE
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    • v.10 no.2
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    • pp.229-239
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    • 2000
  • To reduce the drag rise on the advancing helicopter rotor blade tips, the tip of the blade is modified to have sweep, anhedral and pretwist. The equations of motion of rotor blade with these tip angles were derived using Hamilton principle, programmed using FORTRAN and named as ARMDAS(Advanced Rotorcraft Multidisplinary Design and Analysis System). Rotating frequency analysis of rotor blades with swept tipe was performed that is necessary in conceptual and preliminary design phases of the helicopter design. Vibration analysis of non-rotating blades was also accomplished and compared with MSC/NASTRAN resutls for the basis of comparison with the vibration test data. The rotating frequency analysis of blades with an actual rotor blade data was also performed to verify coded program and to check the possibility of a resonance of an actual rotor blade at the specific rotating speed.

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Optimization of the Multi-chamber Perforated Muffler for the Air Processing Unit of the Fuel Cell Electric Vehicle (연료전지 자동차용 흡기 소음기의 설계 변수 최적화에 관한 연구)

  • Kim, Eui-Youl;Lee, Sang-Kwon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.7
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    • pp.736-745
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    • 2009
  • Fuel cells convert a fuel together with oxygen in a highly efficient electrochemical reaction to electricity and water. Since the electrochemical reaction in the fuel cell stack dose not generate any noise, Fuel cell systems are expected to operated much quieter than combustion engines. However, the tonal noise and the broad band noise caused by a centrifugal compressor and an electric motor cause which is required to feed the ambient air to the cathode of the fuel cell stack with high pressure. In this study, the multi-camber perforated muffler is used to reduce noise. We propose optimized muffler model using an axiomatic design method that optimizes the parameters of perforated muffler while keeping the volume of muffler minimized.