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Simulation model for Francis and Reversible Pump Turbines
Nielsen, Torbjorn K. Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.3
When simulating the dynamic behaviour of a hydro power plant, it is essential to have a good representation of the turbine behaviour. The pressure transients in the system occurs because the flow changes, which the turbine defines. The flow through the turbine is a function of the pressure, the speed of rotation and the wicket gate opening and is, most often described in a performance diagram or Hill diagram. In the Hill diagram, the efficiency is drawn like contour lines, hence the name. A turbines Hill diagram is obtained by performance tests on scaled model in a laboratory. However, system dynamic simulations have to be performed in the early stage of a project, before the turbine manufacturer has been chosen and the Hill diagram is known. Therefore one have to rely on diagrams for a turbine with similar speed number. The Hill diagram is drawn through measured points, so for using the diagram in a simulation program, one have to iterate in the diagram based on curve fitting of the measured points. This paper describes an alternative method. By means of the Euler turbine equation, it is possible to set up two differential equations which represents the turbine performance with good enough accuracy for the dynamic simulations. The only input is the turbine's main geometry, the runner blade in- and outlet angle and the guide vane angle at best efficiency point of operation (BEP). In the paper, simulated turbine characteristics for a high head Francis turbine, and for a reversible pump turbine are compared with laboratory measured characteristics.
[解說] Centreless Precision Grinding of Camshafts as an Automated Operation
Roger Petterson,Torbjorn Lundberg 한국자동차공학회 1989 오토저널 Vol.11 No.3
The development of a microprocessor controlled centreless grinding station has opened the way the production of automobile camshafts-from raw casting to precision-finished part-as a fully automated operation. This results in manufacture to finer tolerances, with part-to-part consistency and a floor-to-floor time of half that needed for alternative production methods. shafts with a grinding length of up to 700 mm can be processed.
Centreless precision grinding of camshafts as an automated operation
Petterson, Roger,Lundberg, Torbjorn The Korean Society of Automotive Engineers 1989 오토저널 Vol.11 No.3
The development of a microprocessor-controlled centreless grinding station has opened the way for the production of automobile camshafts-from raw casting to precision-finished part-as a fully automated operation. This results in manufacture to finer tolerances, with part-to-part consistency and a floor-to-floor time of half that needed for alternative production methods. Shafts with a grinding length of up to 700 mm can be processed.
Influence of Guide Vane Setting in Pump Mode on Performance Characteristics of a Pump-Turbine
Li, Deyou,Wang, Hongjie,Nielsen, Torbjorn K.,Gong, Ruzhi,Wei, Xianzhu,Qin, Daqing Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.2
Performance characteristics in pump mode of pump-turbines are vital for the safe and effective operation of pumped storage power plants. However, the head characteristics are different under different guide vane openings. In this paper, 3-D steady simulations were performed under 13mm, 19mm and 25mm guide vane openings. Three groups of operating points under the three GVOs were chosen based on experimental validation to investigate the influence of guide vane setting on flow patterns upstream and downstream. The results reveal that, the guide vane setting will obviously change the flow pattern downstream, which in turn influences the flow upstream. It shows a strong effect on hydraulic loss (power dissipation) in the guide and stay vanes. It is also found that the hydraulic loss mainly comes from the flow separation and vortices. In addition, in some operating conditions, the change of guide vane opening will change the flow angle at the runner inlet and outlet, which will change the Euler momentum (power input). The joint action of Euler momentum and hydraulic loss results in the change of the head characteristics.
Blade passage modeling strategy for hydraulic turbine
Gong, Ruzhi,Trivedi, Chirag,Dahlhaug, Ole G.,Nielsen, Torbjorn K. Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.4
CFD has played a significant role to investigate the performance and improve the design of hydraulic turbines; however, the improvement of CFD method demands powerful computer resources including time, CPU, memory, and commercial licenses. In present work, both global and local parameters of a high head Francis turbine were studied using several geometrical and interface modelling approaches. The aim of the work is to find suitable strategy for designers to simulate the hydraulic turbines to balance the numerical accuracy and the requirement of computational resources. The geometrical modelling approaches include combinations of turbine components such as, spiral casing, distributor, runner and draft tube. The interface modelling approaches includes, stage, Frozen rotor and transient rotor-stator types. The study showed that the proper combinations of both approaches can effectively reduce the numerical error.
Sofi Fristedt,Anders Wretstrand,Anita Bjorklund,Susan Corr,Torbjorn Falkmer 한국주관성연구학회 2012 Journal of Human Subjectivity Vol.10 No.1
Background/Aim: Community mobility supports participation in activities. However, knowledge about issues that influence community mobility and, hence, participation in activities outside the home is limited. Since participation and community mobility are subjectively defined phenomena, further knowledge from an insider``s perspective is needed. The aim of this study was to identify and describe viewpoints on community mobility and participation in older age. Methods: A Q-methodology study was conducted with 36 male and female participants, including drivers and non-drivers. Participants sorted 45 Q-statements along a most to least continuum, indicating their current habitual situation of mobility and participation in activities outside their homes. Results: Three viewpoints were found and assigned content-describing denominations; "Prefer being mobile by car, "Prefer being mobile by public transport" and "Prefer flexible mobility". Conclusions: All participants were satisfied with their actual participation in activities outside their homes. However, those who preferred to use public transport were less satisfied with their opportunities and possibilities to participate in activities outside their homes. The existing demand-responsive Special Transportation System was not considered to be an attractive enough alternative by any of the participants. Intermediate community mobility options are thus needed for those who can no longer drive or use public transport. 배경/목표: 지역사회의 유동성은 여러 활동의 참여에 영향을 미친다. 그러나 지역사회 유동성에 영향을 미치는 지식과 집 밖에서의 활동 참가는 매우 제한적이다. 참가와 지역사회 유동성이 주관적으로 판단되는 현상이기 때문에, 내부인의 견해가 반영된 더 많은 지식이 요구된다. 이 연구의 목표는 지역사회의 유동성과 참여에 대한 노인들의 견해를 조사하는 것이다. 방법: 36명의 남녀 참가자가 Q 방법론을 통해 연구에 참가하였고, 참가자 중에는 운전자와 비운전자가 포함되어있다. 참가자는 45가지의 Q 진술로 분류하였고, 그 진술은 그들의 유동성에 대한 현재의 습관적 상황과 집 밖에서의 활동에 대한 참여를 반영하고 있다.