Design of Mixed-flow pump for Ns475 Based on Optimum Design Database

김성,이경용,김진혁,윤준용,최영석 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.2

In this study, a mixed-flow pump with a specified specific speed was optimally designed by utilizing computational fluid dynamics (CFD). Additionally, the shape of the mixed-flow pump and flow characteristics depending on the specific speed were studied, in order to development of hydrodynamic design system for mixed-flow pump. A mixed-flow pump consists of an impeller and a diffuser and the shapes of mixed-flow pumps show a certain tendency depending on specific speed. With an analysis of the shapes of a mixed-flow pump, the optimal shape to satisfy design specifications can easily be designed. The design variables of the impeller and diffuser were defined in meridional plane and vane plane development, and optimum design of the impeller and diffuser was carried out by using design of experiment (DOE). The tendencies of design variables depending on specific speed were analyzed by utilizing the shape of optimally designed mixed-flow pump. The mixed-flow pump shape of required design specification was designed by using the tendencies of design variables depending on specific speed. The performance of designed model has been verified using CFD.

Design of Mixed-flow pump for Ns475 Based on Optimum Design Database

Sung Kim,Kyoung-Yong Lee,Jin-Hyuk Kim,Joon-Yong Yoon,Young-Seok Choi 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.2

In this study, a mixed-flow pump with a specified specific speed was optimally designed by utilizing computational fluid dynamics (CFD). Additionally, the shape of the mixed-flow pump and flow characteristics depending on the specific speed were studied, in order to development of hydrodynamic design system for mixed-flow pump. A mixed-flow pump consists of an impeller and a diffuser and the shapes of mixed-flow pumps show a certain tendency depending on specific speed. With an analysis of the shapes of a mixed-flow pump, the optimal shape to satisfy design specifications can easily be designed. The design variables of the impeller and diffuser were defined in meridional plane and vane plane development, and optimum design of the impeller and diffuser was carried out by using design of experiment (DOE). The tendencies of design variables depending on specific speed were analyzed by utilizing the shape of optimally designed mixed-flow pump. The mixed-flow pump shape of required design specification was designed by using the tendencies of design variables depending on specific speed. The performance of designed model has been verified using CFD.

Design optimization for mixed-flow pump impeller by improved suction performance and efficiency with variables of specific speeds

Sung Kim,Yong-In Kim,Jin-Hyuk Kim,Young-Seok Choi 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

In this study, the shape of a mixed-flow pump impeller and its flow characteristics as a function of the specific speed are studied to improve its suction performance and efficiency. The shapes of mixed-flow pump impellers show a trend based on the specific speed. To construct the optimum database, a mixed-flow pump impeller with a specified specific speed is optimally designed using computational fluid dynamics (CFD) and design of experiment (DOE). The design variables of the impeller are defined in the meridional plane and vane plane development for impeller. By analyzing the trends of different mixed-flow pump impeller shapes, the optimized shape that satisfies the design specification can be designed easily. The trend exhibited by the design variables depending on the specific speed is analyzed using the shape of the optimally designed mixed-flow pump impeller. The shape of the mixed-flow pump impeller, as per the required design specification, is designed using the trends of the design variables based on the specific speed. The performance of the designed model is verified using CFD and experimental test.

High performance hydraulic design techniques of mixed-flow pump impeller and diffuser

김성,이경영,김준형,김진혁,정욱희,최영석 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1

In this paper, we describe a numerical study about the performance improvement of a mixed-flow pump by optimizing the design ofthe impeller and diffuser using a commercial computational fluid dynamics (CFD) code and design-of-experiments (DOE). The designvariables of impeller and diffuser in the vane plane development were defined with a fixed meridional plane. The design variables weredefined by the vane plane development, which indicates the blade-angle distributions and length of the impeller and diffuser. The vaneplane development was controlled using the blade-angle in a fixed meridional plane. The blade shape of the impeller and diffuser weredesigned using a traditional method in which the inlet and exit angles are connected smoothly. First, the impeller optimum design wasperformed with impeller design variables. The diffuser optimum design was performed with diffuser design variables while the optimallydesigned impeller shape was fixed. The importance of the impeller and diffuser design variables was analyzed using 2k factorial designs,and the design optimization of the impeller and diffuser design variables was determined using the response surface method (RSM). Theobjective functions were defined as the total head (Ht) and the total efficiency (ηt) at the design flow rate. The optimally designed modelwas verified using numerical analysis, and the numerical analysis results for both the optimum model and the reference model were comparedto determine the reasons for the improved pump performance. A pump performance test was carried out for the optimum model,and its reliability was proved by a comparative analysis of the results of the numerical analysis and an experiment using the optimummodel.

Design Optimization of Mixed-flow Pump in a Fixed Meridional Shape

Kim, Sung,Choi, Young-Seok,Lee, Kyoung-Yong,Kim, Jun-Ho Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.1

In this paper, design optimization for mixed-flow pump impellers and diffusers has been studied using a commercial computational fluid dynamics (CFD) code and DOE (design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser. Geometric design variables were defined by the vane plane development, which indicates the blade-angle distributions and length of the impeller and diffusers. The vane plane development was controlled using the blade-angle in a fixed meridional shape. First, the design optimization of the defined impeller geometric variables was achieved, and then the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Next, design optimizations of the defined diffuser shape variables were performed. The importance of the geometric design variables was analyzed using $2^k$ factorial designs, and the design optimization of the geometric variables was determined using the response surface method (RSM). The objective functions were defined as the total head and the total efficiency at the design flow rate. Based on the comparison of CFD results between the optimized pump and base design models, the reason for the performance improvement was discussed.

Impact of mixer design to reactants mixing characteristics and gas-phase reactions in the mixing region of a hydrocarbon reformer

김선영(Kim, Sunyoung),배중면(Bae, Joongmyeon) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11

Reactant mixing has a critical role in ensuring reformate quality and an important design objective is to achieve sufficiently complete mixture of reactants. For that purpose it is required to understand the coupled transport-kinetics phenomena in the mixing region. Three-dimensional computational fluid dynamics model was developed and validated in previous works. The mixing characteristics in various alternatives of a prototype mixing chamber were compared, and then a reduced reaction kinetics was applied to two extreme designs for investigating the impact of gas-phase reactions. Both designs did not reach threshold ethylene mole fraction of 0.001, but surprisingly more ethylene was generated in the design having better mixing characteristics. The presentation will deliver the development process of coupled transport and kinetics model briefly and the detailed information about the mixing characteristics and gas-phase reactions in two mixer designs.

특수목 조경 설계 검토 단계에서의 혼합현실 도입 가능성에 관한 연구

임진빈,황서준,장재호,김주형,이경태 대한건축학회 2022 대한건축학회논문집 Vol.38 No.8

Information asymmetry is the biggest reason for variations and change orders in the field of construction. These issues lead to increased construction period and cost, legal claims, and disputes. Especially, the design of a special tree is difficult for clients to perceive the description of the tree due to the limited experience and information. Consequently, designers have used representation tools such as 2D CAD or BIM to make their proposals easier for clients to understand more intuitive. However, existing representation tools require professional knowledge and the ability to imagine or shape the information, which intensifies difficulties in communication between practitioners and clients. Thus, more immersive realistic models in virtual-reality or mixed-reality environments are applied in the design review process to support decision-making. In this study, the mixed reality was introduced to determine whether it could be used as a representation tool while supporting the client’s special tree design decision-making. To verify this hypothesis, an experiment, about the installation of a special tree in the landscape design review phase, was conducted to compare mixed reality with the 2D CAD drawing plans, which is the representative design proposal representation. In addition, 12 questionnaires are classified by each category, understanding of space, understanding of greenery, and decision-making supporting. Mann-Whitney U test and paired t-test were conducted to analyze the significance between previous representation tools and mixed-reality about the understanding of space, design, and greenery. In addition, the correlation between understanding and decision-making support for landscape design review was analyzed by applying the Pearson correlation coefficient. As a result, it was found that mixed-reality is more intuitive and easier than 2D CAD drawings to understand essential information such as spatial, design, and scale information in the design review phase of a special tree. Even with the technical limitations of tactility visualization in mixed-reality, quick introduction of this innovative tool would support clients to determine the size and installation location of a special tree. 본 연구는 클라이언트와 건설 전문가간에 발생하는 정보 불균형을 완화하기 위한 방법으로 혼합현실이 클라이언트를 지원하는지 검증하는데 있다. 현실환경과 가상환경을 직관적으로 상호작용하는 혼합현실 기술을 도입하여 사용자들이 기존 설계 검토와 유의한 차이가 있는지 검증하고자 한다. 이를 검증하기 위해 독립변수를 설계 제안 지원 매체로 설정한 후 선행 연구를 토대로 설문 항목들을 작성하였다. 참가자들의 설문 결과를 토대로 t-검정과 pearson 상관 분석을 통해 혼합현실이 기존 설계 제안보다 효과적임을 입증하였다.

다레살람시 BRT 사업(Category 포장 설계법 적용) 도로의 AASHTO Guide for Design of Pavement Structures(1993) 및 한국형 포장 설계법 적용성 연구

이용구,박건호,박태순 한국아스팔트학회 2022 한국아스팔트학회지 Vol.12 No.2

The BRT route has the characteristic of designing two roads with different traffic operation characteristics because the BRT lane operated only by the BRT bus and the mixed traffic lane where passenger cars, trucks and other vehicles are mixed. These two lanes, BRT and Mixed lanes, are separated by separator. Therefore, the pavement design for BRT lanes and mixed traffic lanes for each of 6 routes has the effect of studying the pavement design for 12 routes. If the category design method, AASHTO Guide for design of pavement structures (1993) design method and Korean pavement design method design method are applied to the project, it is possible to secure data for 36 routes with a total of 3 pavement design methods. By using the data for each pavement design method secured in the way, it is possible to compare and analyze the difference in pavement thickness with characteristics according to the pavement design method. In addition, by clearly defining the differences according to the pavement design method, it is judged that further research can be presented in the future by identifying the shortcomings of the pavement design method being used. By using the data for each pavement design method secured in the way, it is possible to compare and analyze the difference in pavement thickness with characteristics according to the pavement design method. In addition, by clearly defining the differences according to the pavement design method, it is judged that further research can be presented in the future by identifying the shortcomings of the pavement design method being used.

상하부 배합을 달리함에 의한 기초 매트 매스콘크리트의 수화열 균열저감

한천구 ( Han Cheon-goo ),김민호 ( Kim Min-ho ) 한국건축시공학회 2017 한국건축시공학회지 Vol.17 No.1

최근 건축물의 기초는 구조체의 안정성과 연관하여 두꺼운 매스콘크리트 형태가 설계되어지고 있다. 그런데, 이와 같은 매트 매스콘크리트는 800mm 이상의 두꺼운 부재로 설계되는 경우가 많아짐에 따라 수화열에 의한 균열이 문제점으로 제기 되고 있다. 이에, 본 연구에서는 상·하부를 구분하여 타설하는 실무조건을 고려하여, 컴퓨터 프로그램상으로 하부와 상부의 최적치를 도출한 다음, 실구조체에 적용 해석치와 실측치간을 비교하므로서 효율적인 수화열균열 저감방안을 제안하고자 하였다. 그 결과, 상·하부 타설 콘크리트간의 저발열 배합정도를 고려한 수화발열량차 적용은 침하균열 방지 및 수화열 균열제어에 효과적인 것으로 밝혀졌다. In this research, considering the practical conditions at field, thermal cracking reducing method was suggested based on the comparative analysis between predicted value and actual value obtained from the actual structure member with optimum mix design. The optimum mix design was deduced from the various mix designs with various proportions of cementitious binder for upper and lower placement lifts of mat-foundation mass concrete. Therefore, before field applications, the mix designs were obtained from the theoretical analysis obtained by MIDAS GEN for upper lift was OPC to FA of 85 to 15, and for lower lift was OPC to FA to BS of 50 : 20 : 30. Based on this mix design, the actual concrete for field was determined and all concrete properties were reached within the predicted range. Especially, the temperature properties of mass concrete at core was approximately 39℃ of temperature difference for low-heat mix design, while approximately 54℃ was shown for normal mix design currently used. Additionally, in the case of cracking index, the low heat mix design showed about 1.4 of relatively high value while the normal mix design showed 1.0. Therefore, it can be stated that applying low heat mix design and different heating technique between upper and lower placement lifts for mass concrete are efficient to control the thermal cracking.

Designing a Rigorous Mixed Methods Research Study

Timothy C. Guetterman 질적연구학회 2017 질적연구 Vol.18 No.1

Mixed methods research involves the integration of qualitative and quantitative research. By combining methods, we are able to yield meta-inferences beyond with either approach could alone. Simply, synergy arises from mixed methods research. Designing mixed methods studies, however, is complicated because it requires considerations beyond those of the qualitative and quantitative approaches used. Therefore, this article presents rigorous components of a mixed methods research design to achieve integration and maximize meta-inferences to address research questions. After providing an introductory overview of mixed methods, I describe the mixed components to consider when designing a study. The components to consider are: 1) identifying a rationale for using mixed methods, 2) writing research questions and a mixed methods title, 3) using rigorous qualitative and quantitative methods, 4) employing a mixed methods design, 5) using intentional sampling strategies, 6) conducting mixed methods integration including meta-inferences, 7) representing the results of integrated mixed methods research in publications, and 8) identifying methodological validity and legitimation issues. The article closes with strategies for writing for publication. A reader can use this article to conceptualize a mixed method study and develop a research design.