• Proceedings of the Korean Magnestics Society Conference
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• 2007.12a
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• pp.17-17
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• 2007

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.8
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• pp.698-703
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• 2016

Francis hydro turbines have been most widely used throughout the world because of their wide range of head and flow rate applications. In most applications, they are used for high heads and flow rates. Currently, Korea is developing technology for Francis hydro turbine design and manufacture. In order to understand the internal details of Francis hydro turbines further, a new Francis turbine model runner is designed and model internal flow characteristics are investigated. The specific speed of the Francis hydro turbine model runner is $Ns=200m-kW-min^{-1}$. The runner blade is designed successfully according to the port area and one-dimensional loss analysis. The best efficiency point of the Francis hydro turbine model achieves 90% at the design condition. CFD analysis yields a hill chart of the Francis hydro turbine model for use in predicting performance.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.3
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• pp.274-281
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• 2013

The variable demand on the energy market requires a great flexibility in operating hydro turbines. However, Francis turbine operated at off-design conditions poses technical challenges related to large unsteady forces given by residual swirl and angular momentum. In order to improve the performance of a Francis turbine, the paper presents a numerical investigation of the 3D flow in the turbine at off-design conditions and discusses the influence of variable guide vane openings on the internal flow of a Francis turbine with the help of computational fluid dynamics. First, the internal flow characteristics of Francis turbine operated by varied guide vane angle at off design condition are computed and the optimal guide vane angle is obtained. Secondly, the Francis turbine is operated with guide vane number varies at the optimal guide vane angle. Finally, pressure contours and velocity distributions in the distributor are discussed and compared.

• Journal of Power System Engineering
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• v.9 no.3
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• pp.39-43
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• 2005

Among many other alternative energy resources, small scale hydropower has been brought into attention as a reliable source of energy today, which had been relatively neglected since 1960s. Present low head of Francis turbines and small scale hydroturbines, however, have limitations in the minimum required head and flow rate for efficient operation. This study attempts to develope the Francis turbine which is expected to run efficiently even in very low head and small flow rate, so that the limitations on the conventional small scale hydropower could alleviated and competition with other alternative energy sources in the changable design conditions could attained. The Francis turbine of a new concept was designed based on changable design conditions, hydrodynamics and theory of power transmission. The result of the study shows that two stages runner is more efficient, cheaper in construction, faster responding, and easier maintaining than single stage runner of Francis turbine

• Proceedings of the Korean Magnestics Society Conference
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• 2006.11a
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• pp.130-131
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• 2006

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.207.1-207.1
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• 2011

The performance of a francis turbine is studied by applying a new performance evaluation tester. the performance of a francis turbine is predicted under several operating conditions and the prediction results are compared with model test data. As a result, it is demonstrated that the present method can predict the performance of a francis turbine with high accuracy and has usefullness as an engineering tool on the performance of hydraulic turbines.

• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.5-10
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• 2016

As a key component of a Francis turbine facility, the runner performance plays a vital role in the performance of the turbine. It is effective and successful to design a Francis turbine runner blade with good performance by one dimensional hydraulic design method. On the basis of one dimensional hydraulic analysis, there are a lot of parameters of the internal flow passage shapes determined by experience. Among those parameters, the effect of port area of blade on the performance of a Francis turbine is investigated in this study. A given Francis turbine model was selected for investigating the port area of blade on the performance. The result shows that the effect of port area of runner blade on the outflow angle from runner passage on the performance is quite significant. A correct exit flow angle reduces the energy loss at draft tube, which has the best efficiency of the turbine model.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.618-626
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• 2012

Suppression of abnormal flow phenomena in the Francis hydro turbine is very important to improve the turbine performance. Especially, as cavitation and cavitation surge makes serious problems when the turbine is operated in the range of partial flow rate, optimum method of suppressing the abnormal flow characteristics is required necessarily. Moreover, as swirl flow in the draft tube of the Francis turbine decreases pressure at the inlet of the draft tube, suppression of the swirl flow can be an useful method of suppressing the occurrence of cavitation. In order to clarifying the possibility of suppressing the swirl flow by J-Groove in the draft tube, a series of CFD analysis has been conducted in the range of partial load, designed condition and excessive flow rate of a Francis turbine. A kind of J-Groove is designed and applied to the draft tube of the Francis hydro turbine model. The pressure contours, circumferential velocity vectors and vortex core regions in the draft tube are compared by the conditions with or without J-Groove. In addition, a group of data about the velocity in the draft is presented to show the influence of J-Groove.

• Journal of Korea Foundry Society
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• v.12 no.5
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• pp.363-364
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• 1992

• Journal of Trauma and Injury
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• v.37 no.1
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• pp.48-59
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• 2024

Purpose: Research on rib fracture management has exponentially increased. Predicting fracture patterns based on the mechanism of injury (MOI) and other possible correlations may improve resource allocation and injury prevention strategies. The Chest Injury International Database (CIID) is the largest prospective repository of the operative and nonoperative management of patients with severe chest wall trauma. The purpose of this study was to determine whether the MOI is associated with the resulting rib fracture patterns. We hypothesized that specific MOIs would be associated with distinct rib fracture patterns. Methods: The CIID was queried to analyze fracture patterns based on the MOI. Patients were stratified by MOI: falls, motor vehicle collisions (MVCs), motorcycle collisions (MCCs), automobile-pedestrian collisions, and bicycle collisions. Fracture locations, associated injuries, and patient-specific variables were recorded. Heat maps were created to display the fracture incidence by rib location. Results: The study cohort consisted of 1,121 patients with a median RibScore of 2 (range, 0-3) and 9,353 fractures. The average age was 57±20 years, and 64% of patients were male. By MOI, the number of patients and fractures were as follows: falls (474 patients, 3,360 fractures), MVCs (353 patients, 3,268 fractures), MCCs (165 patients, 1,505 fractures), automobile-pedestrian collisions (70 patients, 713 fractures), and bicycle collisions (59 patients, 507 fractures). The most commonly injured rib was the sixth rib, and the most common fracture location was lateral. Statistically significant differences in the location and patterns of fractures were identified comparing each MOI, except for MCCs versus bicycle collisions. Conclusions: Different mechanisms of injury result in distinct rib fracture patterns. These different patterns should be considered in the workup and management of patients with thoracic injuries. Given these significant differences, future studies should account for both fracture location and the MOI to better define what populations benefit from surgical versus nonoperative management.