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Simulation and Experiment Research of Aerodynamic Performance of Small Axial Fans with Struts

Journal of Thermal Science 2016年第3期25卷 216-222页

作者： CHU Wei LIN Peifeng ZHANG Li JIN Yingzi WANG Yanping heuy dong kim Toshiaki Setoguchi Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech University Xuelin Road 928 0571 Hangzhou China Department of Application & Engineering Zhejiang Economic & Trade Polytechnical Xuelin Road 280 0571Hangzhou School of Mechanical Engineering Andong National University Seongcheon-Dong1375 Gyeongdong RD 760-749Andong Korea Department of Mechanical Engineering Saga University Honjo-machi 840-8502Saga Japan

Interaction between rotor and struts has great effect on the performance of small axial fan systems. The small axial fan systems are selected as the studied objects in this paper, and four square struts are downstream of the rotor. The cross section of the struts is changed to the cylindrical shapes for the investigation： one is in the same hy- draulic diameter as the square struts and another one is in the same cross section as the square struts. Influence of the shape of the struts on the static pressure characteristics, the internal flow and the sound emission of the small axial fans are studied. Standard K-s turbulence model and SIMPLE algorithm are applied in the calculation of the steady fluid field, and the curves of the pressure rising against the flow rate are obtained, which demonstrates that the simulation results are in nice consistence with the experimental data. The steady calculation results are set as the initial field in the unsteady calculation. Large eddy simulation and PISO algorithm are used in the transient calculation, and the Ffowcs Williams-Hawkings model is introduced to predict the sound level at the eight monitoring points. The research results show that： the static pressure coefficients of the fan with cylindrical struts increase by about 25% compared to the fan with square strum, and the efficiencies increase by about 28.6%. The research provides a theoretical guide for shape optimization and noise reduction of small axial fan with struts.

关键词： struts shape interaction aerodynamic performance

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The Effect of Non-Equilibrium Condensation on Supersonic Air Flows over Rectangular Cavities

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Journal of Thermal Science 2007年第1期16卷 33-39页

作者： Miah MD. Ashraful ALAM Md. Mahbubul ALAM Shigeru MATSUO Kenbu TERAMOTO Toshiaki SETOGUCHI heuy dong kim Shen YU Department of Mechanical Engineering Khulna University of Engineering ＆ Technology Khulna-9203 Bangladesh Department of Mechanical Engineering Saga University 1 Honjo-machi Saga-shi Saga 840-8502 Japan School of Mechanical Engineering College of Natural Science Andong National University 388 Song Cheon Dong Andong Kyung Pook Republic of Korea Institute of Engineering Thermophysics Chinese Academy of Sciences EO. Box 2706 Beijing 100080 China

Numerical simulations have been carded out for a supersonic two-dimensional flow over open, rectangular cavities （length-to-depth ratios are L/D = 1.0 and 3.0） in order to investigate the effect of non-equilibrium condensation of moist air on supersonic internal flows around the cavity for the flow Mach number 1.83 at the cavity entrance. In the present computational investigation, a condensing flow was produced by an expansion of moist air in a Laval nozzle. The computational results showed that the upstream traveling compression waves become weaker than those without the condensation. Consequently, the weaker compression waves cannot excite the shear layer strongly and amplitudes of oscillation in the cavity became smaller than those without the condensation. The occurrence of the non-equilibrium condensation in case of L/D = 1.0 affected strongly the amplitude and frequency of oscillation in the cavity compared with L/D = 3.0.

关键词： compressible flow supersonic cavity oscillation non-equilibrium condensation numerical simulation

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Optimization of operating conditions in the steam turbine blade cascade using the black-box method

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Propulsion and Power Research 2023年第4期12卷 467-485页

作者： Vahid Sadrian Esmail Lakzian Davood Hoseinzade Behrad Haghighi M.M.Rashidi heuy dong kim Center of Computational Energy Department of Mechanical EngineeringHakim Sabzevari UniversitySabzevarIran Department of Mechanical Engineering Andong National UniversityAndongSouth Korea Department of Mechanical Engineering Vali-e-Asr University of RafsanjanRafsanjanIran Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China Faculty of Science University of JohannesburgPO Box 524Auckland Park 2006South Africa

Water droplets cause corrosion and erosion,condensation loss,and thermal efficiency reduction in low-pressure steam *** this study,multi-objective optimization was carried out using the black-box method through the automatic linking of a genetic algorithm(GA)and a computational fluid dynamics(CFD)code to find the optimal values of two design variables(inlet stagnation temperature and cascade pressure ratio)to reduce wetness in the last stages of *** wet steam flow numerical model was used to calculate the optimization parameters,including wetness fraction rate,mean droplet radius,erosion rate,condensation loss rate,kinetic energy rate,and mass flow *** the validation results showed a good agreement between the experimental data and the numerical *** to the optimization results,the inlet stagnation temperature and the cascade pressure ratio were proposed to be 388.67(K)and 0.55(-),*** particular,the suggested optimaltemperature and pressure ratio improved the liquid mass fraction and mean droplet radius by about 32%and 29%,***,in the identified optimal operating state,the ratios of erosion,condensation loss,and kinetic energy fell by 76%,32.7%,and 15.85%,respectively,while the mass flow rate ratio rose by 0.68%.

关键词： Black-box optimization Wet steam flow Steam turbine cascade Erosion rate Condensation loss

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Experimental Investigation on Noise Suppression in Supersonic Jets from Convergent-Divergent Nozzles with Baffles

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Journal of Thermal Science 2003年第3期12卷 260-263,269页

作者： Yoshiaki Miyazato Yong-Hun Kweon Toshiyuki Aoki Mitsuharu Masuda Kwon-Hee Lee heuy-dong kim Toshiaki Setoguchi Kazuyasu Matsuo Graduate School of Engineering Sciences Kyushu University 6-1 Kasuga-kouen Kasuga Fukuoka816-8580 JapanSchool of Mechanical Engineering Andong National University 388 Songchun-dong AndongKyungbuk 760-749 KoreaGraduate School of Engineering Sciences Kyushu University 6-1 Kasuga-kouen Kasuga Fukuoka816-8580 JapanGraduate School of Engineering Sciences Kyushu University 6-1 Kasuga-kouen Kasuga Fukuoka816-8580 JapanDepartment of Mechanical Engineering Saga University 1 Honjo-machi Saga Saga 840-8502 JapanSchool of Mechanical Engineering Andong National University 388 Songchun-dong AndongKyungbuk 760-749 KoreaDepartment of Mechanical Engineering Saga University 1 Honjo-machi Saga Saga 840-8502 JapanFaculty of Environmental Engineering The University of Kitakyushu 1-1 Hibikino Wakamatsu-kuKitakyushu Fukuoka 808-0135 Japan

The acoustic properties of supersonic jet noise from a convergent-divergent nozzle with a baffle have been studied experimentally over the range of nozzle pressure ratios from 2.0 to 8.0. Acoustic measurements were conducted in a carefully designed anechoic room providing a free-field environment. A new approach for screech noise suppression by a cross-wire is proposed. Schlieren photographs were taken to visualize the shock wave patterns in the supersonic jet with and without the cross-wire. The effects of the baffle and the cross-wire on acoustic properties are discussed. It is shown that the baffle has little effect on the screech frequency for the underexpanded supersonic jet without the cross-wire. Also, the cross-wire introduced in supersonic jets is found to lead to a significant reduction in overall sound pressure level.

关键词：超音速流动噪声控制实验研究收敛-扩散喷管流体力学超音速喷射

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Three-Dimensional Structure of Non-Equilibrium Homogeneous Condensation Flow in a Supersonic Rectangular Nozzle

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Open Journal of Fluid Dynamics 2021年第2期11卷 55-66页

作者： Shibanul Haque Shigeru Matsuo heuy-dong kim Graduate School of Science & Engineering Saga University Saga Japan Department of Science and Engineering Saga University Saga Japan School of Mechanical Engineering Andong National University Andong Korea

Numerical simulations have been carried out for a supersonic three-dimensional rectangular arc nozzle, where a secondary flow toward the center of the curvature occurs due to the shape of the nozzle. It is known that secondary flow causes longitudinal vortices to form near the wall of the nozzle corner, making the nozzle outlet flow unstable and induces loss of transport energy. When the working fluid is a condensable gas with relatively large latent heat such as moist air or steam, rapid accelerated expansion in the nozzle causes non-equilibrium condensation due to supersaturation. After the release of latent heat during phase transition, nozzle flow continues expanding at an equilibrium saturation condition. In the absence of foreign particles, e.g. ions or dust particles, condensation nuclei are formed in the gas itself causing non-equilibrium homogeneous condensation. Supersonic nozzle flow properties vary considerably due to the occurrence of condensation phenomenon. The objective of this study is to investigate the effect of non-equilibrium homogeneous condensation on the longitudinal vortices which form in the range close to the corner of rectangular arc nozzle numerically.

关键词： Compressible Flow Non-Equilibrium Condensation Supersonic Nozzle Vortex Simulation

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Study of Secondary Flow Modifications at Impeller Exit of a Centrifugal Compressor

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Open Journal of Fluid Dynamics 2012年第4期2卷 248-256页

作者： Surendran Anish Nekkanti Sitaram heuy dong kim Andong National University Andong South Korea FMTRC Daejoo Machinery Co. Ltd. Daegu South Korea Indian Institute of Technology Madras Chennai India

A computational study has been conducted to analyze the performance of a centrifugal compressor under various levels of impeller-diffuser interactions. The study has been conducted using a low solidity vaned diffuser (LSVD), a conventional vaned diffuser (VD) and a vaneless diffuser (VLD). The study is carried out using Reynolds-Averaged Navier- Stokes simulations. A commercial software ANSYS CFX is used for this purpose. The extent of diffuser influence on impeller flow is studied by keeping the diffuser vane leading edge at three different radial locations. Detailed flow analysis inside the impeller passage shows that the strength and location of the wake region at the exit of impeller blade is heavily depended upon the tip leakage flow and the pressure equalization flow. Above design flow rate, the diffuser vane affects only the last twenty percent of the impeller flow. However, below design flow rate, keeping vane closer to the impeller can cause an early stall within the impeller. Small negative incidence angle at the diffuser vane is helpful in order to reduce the losses at the impeller exit.

关键词： Secondary Flow Impeller CFD Centrifugal Compressor

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Computational Study on Micro Shock Tube Flows with Gradual Diaphragm Rupture Process

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Open Journal of Fluid Dynamics 2012年第4期2卷 235-241页

作者： Arun Kumar Rajagopal heuy dong kim Toshiaki Setoguchi Department of Mechanical Engineering Andong National University Andong South Korea Institute of Ocean Technology Saga University Saga Japan

Gas flows through micro shock tubes are widely used in many engineering applications such as micro engines, particle delivery devices etc. Recently, few studies have been carried out to explore the shock wave excursions through micro shock tubes at very low Reynolds number and at rarefied gas condition. But these studies assumed centered shock and expansion waves, which are generally produced by instantaneous diaphragm rupture process. But in real scenario, the diaphragm ruptures with a finite rupture time and this phenomenon will significantly alter the shock wave propagation characteristics. In the present research, numerical simulations have been carried out on a two dimensional micro shock tube model to simulate the effect of finite diaphragm rupture process on the wave characteristics. The rarefaction effect was simulated using Maxwell’s slip wall equations. The results show that shock wave attenuates rapidly in micro shock tubes compared to conventional macro shock tubes. Finite diaphragm rupture causes the formation of non-centered shock wave at some distance ahead of the diaphragm. The shock propagation distance is also drastically reduced by the rupture effects.

关键词： Diaphragm Rupture Expansion Wave Micro Shock Tube Rarefaction Unsteady Flow

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Heat Transfer Enhancement of Cu-H<sub>2</sub>O Nanofluid with Internal Heat Generation Using LBM

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Open Journal of Fluid Dynamics 2013年第2期3卷 92-99页

作者： Mohammad Abu Taher Yeon Won Lee heuy dong kim School of Mechanical Engineering Andong National University Andong South Korea School of Mechanical Engineering Pukyong National University Busan South Korea

Fluid flow and heat transfer analysis of Cu-H2O nanofluid in a square cavity using a Thermal Lattice Boltzmann Method (TLBM) have been studied in the present work. The LBM has built up on the D2Q9 model and the single relaxation time method called the Lattice-BGK (Bhatnagar-Gross-Krook) model. The effect of suspended nanoparticles on the fluid flow and heat transfer analysis have been investigated for different non dimensional parameters such as particle volume fraction (φ) and particle diameters (dp) in presence of internal heat generation (q) of nanoparticles. It is seen that flow behaviors and the average rate of heat transfer in terms of the Nusselt number (Nu) as well as the thermal conductivity of nanofluid are effectively changed with the different controlling parameters such as particle volume fraction (2% ≤ φ ≤ 10%), particle diameter (dp = 5 nm to 40 nm) with fixed Rayleigh number, Ra = 105. The present results of the analysis are compared with the previous experimental and numerical results for both pure and nanofluid and it is seen that the agreement is good indeed among the results.

关键词： Nanofluid Lattice-Boltzmann Volume Fractions Particle Diameter Heat Generation

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Numerical Study on the Effect of Unsteady Downstream Conditions on Hydrogen Gas Flow through a Critical Nozzle

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Open Journal of Fluid Dynamics 2012年第4期2卷 137-144页

作者： Junji Nagao Shigeru Matsuo Toshiaki Setoguchi heuy dong kim Department of Mechanical Engineering Saga University Saga Japan Graduate School of Science and Engineering Saga University Saga Japan Institute of Ocean Energy Saga University Saga Japan School of Mechanical Engineering Andong National University Andong Korea

A critical nozzle (sonic nozzle) is used to measure the mass flow rate of gas. It is well known that the coefficient of discharge of the flow in the nozzle is a single function of Reynolds number. The purpose of the present study is to investigate the effect of unsteady downstream condition on hydrogen gas flow through a sonic nozzle, numerically. Navier-Stokes equations were solved numerically using 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration. A standard k-ε model was used as a turbulence model. The computational results showed that the discharge coefficients in case without pressure fluctuations were in good agreement with experimental results. Further, it was found that the pressure fluctuations tended to propagate upstream of nozzle throat with the decrease of Reynolds number and an increase of amplitude of pressure fluctuations.

关键词： Compressible Flow Critical Nozzle Pressure Fluctuation Measurement Supersonic Flow

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Computational Analysis of Mixing Guide Vane Effects on Performance of the Supersonic Ejector-Diffuser System

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Open Journal of Fluid Dynamics 2012年第3期2卷 45-55页

作者： Fan Shi Kong heuy dong kim Ying Zi Jin Toshiaki Setoguchi College of Mechanical Engineering & Automation Zhejiang Sci-Tech University Hangzhou China Department of Mechanical Engineering Saga University Saga Japan School of Mechanical Engineering Andong National University Andong Korea

The flow field in the ejector-diffuser system and its optimal operation condition are hardly complicated due to the complicated turbulent mixing, compressibility effects and even flow unsteadiness which are generated inside the ejector- diffuser system. This paper aims at the improvement in ejector-diffuser system by focusing attention on entrainment ratio and pressure recovery. Several mixing guide vanes were installed at the inlet of the secondary stream for the purpose of the performance improvement of the ejector system. A Computational Fluid Dynamics (CFD) method based on Fluent has been applied to simulate the supersonic flows and shock waves inside the ejector. A finite volume scheme and density-based solver with coupled scheme were applied in the computational process. Standard k-ω turbulent model, implicit formulations were used considering the accuracy and stability. Previous experimental results showed that more flow vortexes were generated and more vertical flow was introduced into the stream under a mixing guide vane influence. Besides these effects on the secondary stream, the mixing guide vane effects on the shock system of the primary stream were also investigated in this paper. Optimal analysis results of the mixing guide vane effects were also carried out in detail in terms of the positions, lengths and numbers to achieve the best operation condition. The comparison of ejector performance with and without the mixing guide vane was obtained. The ejector-diffuser system performance is discussed in terms of the entrainment ratio, pressure recovery as well as total pressure loss.

关键词： Ejector-Diffuser System Mixing Guide Vane Shock Wave Compressible Flow Supersonic Flow

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