• Title/Summary/Keyword: Flow Prediction

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Study on a Prediction of Noise Attenuation Performance of Automotive Mufflers (자동차 소음기의 소음성능 예측에 관한 연구)

  • 양기영;황원걸;기창두
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.389-394
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    • 1994
  • The lattice filter formed transfer function has the advantage of computer simulation in the analysis of muffler. The transfer function is derived by using z-transformation for perforated elements in through-flow, cross-flow and reverse-flow type. A computer program for the prediction of the performance of automotive mufflers is developed using the transfer functions for uniform tube, open termination, expansion element, perforated elements, etc. The analytical results are verified by comparing with the experimental results for the transmission loss of a muffer. The effect of geometric configuration change of the muffler was invesigated in order to improve the performance of noise attenuation.

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A Study on the Flow Characteristics of a Butterfly Valve in Fire Protection (소화용 버터플라이 밸브의 유동특성에 관한 연구)

  • 이동명;김엽래
    • Fire Science and Engineering
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    • v.16 no.4
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    • pp.59-64
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    • 2002
  • Investigation of flow characteristics on pressure loss and cavitations of the butterfly valve has been carried out. The pressure loss coefficient on opening angle of valve has been formulated by applying the Carnot's equations. Cavitations (such as cavitation Inception, super cavitation inception, cavitation damage inception, choking cavitation) have been predicted from the pressure loss coefficient of valve. The prediction of pressure loss and cavitation has been carried out change of the thickness ratio on opening angle of valve. The prediction data is utilize to necessary engineering data to develope of the butterfly valve.

A study on the performance prediction of 4 cycle 4 cylinder S.I. engine considering the unsteady flow in the intake and exhaust pipes (흡배기 관내의 비정상 유동을 고려한 4사이클, 4기통 전기.점화 기관의 성능 예측에 관한 연구)

  • 박성서;김응서
    • Journal of the korean Society of Automotive Engineers
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    • v.13 no.6
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    • pp.72-81
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    • 1991
  • In this study, the analytic investigation of the unsteady flow in the intake and exhaust pipes has been carried out using the method of characteristics in one direction to predict volumetric efficiency. Based on the calculated volumetric efficiency, three zone predictive analysis using Wiebe function was applied to predict the engine performance and the results were compared with experiment. Mixture in the cylinder is subdivided into three zones during combustion process in this analysis; adiabatic core zone, thermal boundary layer zone and unburned zone. In each zone, pressure, temperature and gas composition have been calculated. In conclusion, it is possible to take account of the intake and exhaust pipe tuning effect in predicting the engine performance, by the analytic solution of the unsteady flow in the pipes, and comparison of prediction with experimental results shows a good agreement on the pressure variation in the intake and exhaust pipes which has a direct influence on the volumetric efficiency and performance of the engine.

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Performance Evaluation of a Main Coolant Pump for the Modular Nuclear Reactor by Computational Fluid Dynamics (전산해석에 의한 일체형 원자로용 주냉각재 펌프의 성능분석)

  • Yoon Eui-Soo;Oh Hyoung-Woo;Park Sang-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.8 s.251
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    • pp.818-824
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    • 2006
  • The hydrodynamic performance analysis of an axial-flow main coolant pump for the modular nuclear reactor has been carried out using a commercial computational fluid dynamics (CFD) software. The prediction capability of the CFD software adopted in the present study was validated in comparison with the experimental data. Predicted performance curves agree satisfactorily well with the experimental results for the main coolant pump over the normal operating range. π Ie prediction method presented herein can be used effectively as a tool for the hydrodynamic design optimization and assist the understanding of the operational characteristics of general purpose axial-flow pumps.

Optimum Design of Axial-Flow Fans Including Noise Parameters (소음파라메터를 고려한 축류송풍기의 최적설계)

  • Son, B.J.;Lee, S.H.;Yoon, S.J.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.1
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    • pp.1-12
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    • 1995
  • In order to seek various relationships among many design parameters employed in the design of the axial-flow fans the program which generates acoustic spectrum has been developed and its validity verified. Outputs of the program, with other outputs from a formerly developed performance prediction program, have been used to form a multi-objective function, for which an optimal design process was carried out. The present analysis shows that overall noise level and efficiency has contrasting trends, and the chord length turns out to be the most critical design variable. In the chosen design case of requirements $Q=2000m^2/min$, ${\Delta}P_s=67mmAq$, D=1.4m, the chord length of 0.2059m minimizes the overall noise level, while chord length of 0.1254m maximizes the efficiency. The resulting chord length in the balanced optimization is 0.1809m.

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PREDICTION OF COMBINED SEWER OVERFLOWS CHARACTERIZED BY RUNOFF

  • Seo, Jeong-Mi;Cho, Yong-Kyun;Yu, Myong-Jin;Ahn, Seoung-Koo;Kim, Hyun-Ook
    • Environmental Engineering Research
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    • v.10 no.2
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    • pp.62-70
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    • 2005
  • Pollution loading of Combined Sewer Overflows (CSOs) is frequently over the capacity of a wastewater treatment plant (WWTP) receiving the water. The objectives of this study are to investigate water quality of CSOs in Anmyun-ueup, Tean province and to apply Storm Water Management Model to predict flow rate and water quality of the CSOs. The capacity of a local WWTP was also estimated according to rainfall duration and intensity. Eleven water quality parameters were analyzed to characterize overflows. SWMM model was applied to predict the flow rate and pollutant load of CSOs during rain event. Overall, profile of the flow and pollutant load predicted by the model well followed the observed data. Based on model prediction and observed data, CSOs frequently occurs in the study area, even with light precipitation or short rainfall duration. Model analysis also indicated that the local WWTP’s capacity was short to cover the CSOs.

Computational Grid Generation for Aero-Performance Prediction of Multi-staged Axial Compressors (다단축류압축기의 공력성능 예측용 계산격자 생성기법 연구)

  • Chung, H.T.;Kim, J.S.
    • Journal of Power System Engineering
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    • v.2 no.1
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    • pp.39-44
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    • 1998
  • Computational grids used in the numerical simulation of multi staged turbomachinery flow fields are generated. A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid for multi-row topologies. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The input module is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The final grids generated from each module of the system are used as the preprocessor for the performance prediction of the single row cascades and the flow simulation inside the multi staegd blade passage. Application to low pressure compressor of industrial gas turbine engines was demonstrated to be very reliable and practical in support of design activities.

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Development of Noise Analysis Software-'NASPFA' in Medium-to-high Frequency Ranges using Power Flow Boundary Element Method (파워흐름경계요소법을 이용한 중고주파 소음해석 소프트웨어 'NASPFA' 개발)

  • Lee, Ho-Won;Hong, Suk-Yoon;Kwon, Hyun-Wung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.949-953
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    • 2004
  • In this paper, Power Flow Boundary Element Method(PFBEM) is studied as the numerical method for the vibration and sound predictions of complex structures in medium-to-high frequency ranges. NASPFA, the sound analysis software based on PFBEM, is developed and is used for the vibro-acoustic analysis. And also the developed software is used for the prediction of interior and exterior sound fields of vibrating structures and for the analysis of the multi-domain problems. To verify the accuracy, NASPFA is applied to the prediction of the energy distribution in the simple structures, and its results are compared with exact PFA solutions. And various practical vehicle systems are modeled and the distributions of the acoustical energy density are successfully predicted.

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Prediction of Heat Transfer in Asymmetric Sudden Expansion Flows by using the Modified Boundary Layer Equations (비대칭 급확대 관로 유동장 내의 열전달 해석에 수정된 경계층 방정식의 적용 가능성 추정)

  • Lyu, Myoung-Seok;Maeng, Joo-Sung
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.14 no.4
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    • pp.293-299
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    • 1985
  • This paper describes an economical prediction procedure for heat transfer phenomenon through a channel containing an abrupt asymmetric expansion in flow cross-seetional area. Numerical solutions for the flow field are obtained by the finite difference numerical method applied to the modified boundary layer equations. Modified boundary energy equation is used to analyze heat transfer as modified boundary momentum equation. Predictions of the method compare very favorable with exprimental data. Results of this study by modified boundary layer equation are as follows : 1. The computation time required for the scheme is at least an order of magnitude less than for the numerical solution of the full Navier-stokes and Energy eguations. 2. In laminar flow, the maximum heat transfer occurs downstream of the reattachment point.

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The Effect of Flow Distribution on Transient Thermal Behaviour of CDPF during Regeneration (배기의 유속분포가 CDPF의 재생 시 비정상적 열적 거동에 미치는 영향)

  • Jeong, Soo-Jin;Lee, Jeom-Joo;Choi, Chang-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.2
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    • pp.10-19
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    • 2009
  • The working of diesel particulate filters(DPF) needs to periodically burn soot that has been accumulated during loading of the DPF. The prediction of the relation between an uniformity of gas velocity and soot regeneration efficiency with simulations helps to make design decisions and to shorten the development process. This work presents a comprehensive combined 'DOC+CDPF' model approach. All relevant behaviors of flow fluid are studied in a 3D model. The obtained flow fields in the front of DPF is used for 1D simulation for the prediction of the thermal behavior and regeneration efficiency of CDPF. Validation of the present simulation are performed for the axial and radial direction temperature profile and shows goods agreement with experimental data. The coupled simulation of 3D and 1D shows their impact on the overall regeneration efficiency. It is found that the flow non-uniformity may cause severe radial temperature gradient, resulting in degrading regeneration efficiency.