• Title/Summary/Keyword: Aeroacoustic noise

Search Result 105, Processing Time 0.027 seconds

헬리콥터 테일팬용 팬-덕트의 공력소음해석 및 소음저감연구

  • Chung, Ki-Hoon;Kang, Hee-Jung;Kim, Hae-Dong;Hwang, Chang-Jeon
    • Aerospace Engineering and Technology
    • /
    • v.3 no.1
    • /
    • pp.45-55
    • /
    • 2004
  • In this study, a time marching free wake method was used for the aerodynamic analysis and the boundary element method was used for the aeroacoustic analysis of the Tail Fan, respectively. In addition, variations of blades position in duct were performed and the aeroacoustic analysis shows a marginal improvement in noise level.

  • PDF

Computation of serrated trailing edge flow and noise using a hybrid zonal RANS-LES

  • Kim, Tae-Hyung;Lee, Seung-Hoon;Lee, Soo-Gab
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2012.04a
    • /
    • pp.414-419
    • /
    • 2012
  • The evaluation of a zonal RANS-LES approach is documented for the prediction of broadband noise generated by the flow past unmodified and serrated airfoil trailing edges at a high Reynolds number. A multi-domain decomposition is considered, where the acoustic sources are resolved with a LES sub-domain embedded in the RANS domain. A stochastic vortex method is used to generate synthetic turbulent perturbations at the RANS-LES interface. The simulations are performed with a general-purpose unstructured control-volume code FLUENT. The far-field noise is calculated using the aeroacoustic analogy of Ffowcs Williams-Hawkings. The results of the simulation are validated through the full-scaled wind turbine acoustic measurements. It is found that the present approach is adequate for predicting noise radiation of serrated trailing edge flow for low noise rotor system.

  • PDF

Computation of Serrated Trailing Edge Flow and Noise Using a Hybrid Zonal RANS-LES (혼합 영역 RANS-LES를 이용한 톱니 뒷전 유동 및 소음장의 계산)

  • Kim, Tae-Hyung;Lee, Seung-Hoon;Lee, Soo-Gab
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.22 no.5
    • /
    • pp.444-450
    • /
    • 2012
  • The evaluation of a zonal RANS-LES approach is documented for the prediction of broadband noise generated by the flow past unmodified and serrated airfoil trailing edges at a high Reynolds number. A multi-domain decomposition is considered, where the acoustic sources are resolved with a LES sub-domain embedded in the RANS domain. A stochastic vortex method is used to generate synthetic turbulent perturbations at the RANS-LES interface. The simulations are performed with a general-purpose unstructured control-volume code FLUENT. The far-field noise is calculated using the aeroacoustic analogy of Ffowcs Williams-Hawkings. The results of the simulation are validated through the full-scaled wind turbine acoustic measurements. It is found that the present approach is adequate for predicting noise radiation of serrated trailing edge flow for low noise rotor system.

Analysis on Performance of Axial Flow Fan for Outdoor Unit of Air-conditioner: Noise Characteristics (에어컨 실외기용 축류홴의 성능에 관한 연구: 소음 특성)

  • Kim, Yong-Hwan;Lee, Jang-Ho
    • The KSFM Journal of Fluid Machinery
    • /
    • v.13 no.5
    • /
    • pp.29-34
    • /
    • 2010
  • In this paper, aerodynamic noise of axial flow fans for outdoor unit of air-conditioner was analyzed by both experiment and numerical simulation. The three-dimensional incompressible turbulent flow was predicted by the commercial computational fluid dynamics code SC/Tetra, while the aeroacoustic noise of an axial flow fan was predicted by FlowNoise. Computations and experiments were performed with two types of axial flow fans, in which very different noise source distributions were presented. The results obtained from this study are expected to show the way to reduce the noise of axial flow fans in industrial applications.

Development of the Helicopter Noise Prediction Code and its Applications (헬리콥터 소음 예측 코드 개발 및 적용사례)

  • Wie, Seong-Yong;Kim, Do-Hyung;Kang, Hee Jung;Chung, Ki-Hoon;Hwang, Changjeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2014.10a
    • /
    • pp.904-910
    • /
    • 2014
  • The Helicopter noise analysis code was developed using Farassat's Formular 1A based on Ffowcs-Williams and Hawkings equation and Lowson's Formula which contains single loading noise source concept. HART-II(Higher harmonic control Aeroacoustic Rotor Test), STAR(Smart-Twisting Active Rotor) and Active-tab Rotor were computed and analyzed by using developed noise code. The results of these rotor noise prediction are explained and its applicability would be mentioned in this paper.

  • PDF

Numerical Prediction of Aerodynamic Noise from Rotors (회전익 공력소음의 수치적 예측)

  • 이정한;이수갑
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1997.04a
    • /
    • pp.581-587
    • /
    • 1997
  • Numerical predictions of aerodynamic noise radiated by subsonic rotors are carried out. A time domain approach for Ffowcs-Williams Hawkings equation of acoustic analogy is used in developing a comprehensive rotor/fan noise prediction program to handle both arbitrary blade shapes and loading conditions. Since only the aeroacoustic aspects of rotors are considered here, the calculations are carried out for rotors with simple aerodynamic characteristics. Broadband noise from ingestion of turbulence is also considered. By incorporating discrete frequency noise prediction of steady loading with broadband spectrum, much better correlation at the low frequency region with experimental data is obtaind. The contributions from different noise mechanisms can also be analysed through this method.

  • PDF

An Experimental Analysis of the Contributions to the Radiated Noise due to Panel Vibration in a Fan Unit (공조기기 판넬 진동으로 인한 방사소음의 실험적 기여도 분석)

  • Kook, Hyung-Seok;Huh, Seung-Jin;Ko, Kang-Ho;Lee, Jae-Hyung;Hong, Seok-In;Kim, Jin-Yong
    • Proceedings of the KSME Conference
    • /
    • 2001.06b
    • /
    • pp.192-197
    • /
    • 2001
  • This study is concerned with the reduction of noise radiation by an industrial fan unit. Among the noise sources involved in the fan unit, this article is focused on the noise source due to vibration of panels of the unit housing. It is shown here that noise radiation associated with the panel vibration can be as significant in some frequency ranges as that associated with other noise sources such as aeroacoustic fan noise.

  • PDF

A Computerized Design System of the Axial Fan Considering Performance and Noise Characteristics (성능 및 소음특성을 고려한 축류 팬 설계의 전산 체계)

  • Lee, Chan;Kil, Hyun-Gwon
    • The KSFM Journal of Fluid Machinery
    • /
    • v.13 no.2
    • /
    • pp.48-53
    • /
    • 2010
  • A computerized design system of axial fan is developed for constructing 3-D blade geometry and predicting both aerodynamic performance and noise. The aerodynamic blading design of fan is conducted by blade angle distribution, camber line determination, airfoil thickness distribution and blade element stacking along spanwise distance. The internal flow and the aerodynamic performance of designed fan are predicted by the through-flow modeling technique with flow deviation and pressure loss correlations. Based on the predicted internal flow field and performance data, fan noise is predicted by two models for discrete frequency and broadband noise sources. The present predictions of the flow distribution, the performance and the noise level of actual fans are well agreed with measurement results.

A Prediction of Airflow-Induced Noise in DVD Drive using Acoustic Analogy (음향상사이론을 이용한 DVD Drive 내에서의 유동소음 예측)

  • Yoo, Seung-Won;Lee, Jong-Soo;Min, Oak-Key
    • Proceedings of the KSME Conference
    • /
    • 2000.11b
    • /
    • pp.502-507
    • /
    • 2000
  • This paper presents the numerical prediction of airflow-induced sound in DVD drives. Computational fluid dynamics (CFD) is first conducted to evaluate flow field characteristics due to the high-speed disk rotation, and to support the acoustic analysis. The acoustic analogy based on Ffowcs Williams-Hawkings (FW-H) equation is adopted to predict aeroacoustic noise patterns. The integral solution for quadrupole volume source is included to identify the turbulence noise generated inside the DVD tray. Near-field noise is strongly affected by the flow field characteristic, which is caused by the complex shape of the tray. For a mid-field, the quadrupole noise play as a counterpart of thickness noise or loading noise, resulting in a different pattern compared with those in the near field.

  • PDF

Design and Noise Analysis Software of Fans (홴 설계 및 소음 해석 소프트웨어)

  • 전완호;백승조;김창준
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2001.11a
    • /
    • pp.270-274
    • /
    • 2001
  • Fans are widely used in household electrical appliances due to their easy usage and high performance for cooling capacity. However, the noise generated by these fans causes one of serious problems. LG electronics makes the intranet software for design and analysis of fan. Axial, sirocco and centrifugal fan can be designed and analyzed by using the IFD(Intranet Based Fans Design) software. In order to calculate the aeroacoustic noise of a fan, the numerical method, which can calculate the acoustic pressure at the blade passing frequency and its higher harmonic frequencies, has been developed. To calculate the unsteady resultant force of the blade, vortex method is used. This paper shows the overview of the software and validates the accuracy of predicted noise of fan.

  • PDF