Overload Surge Investigation Using CFD Data

Flemming, Felix,Foust, Jason,Koutnik, Jiri,Fisher, Richard K. Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.4

Pressure oscillations triggered by the unstable interaction of dynamic flow features of the hydraulic turbine with the hydraulic plant system - including the electrical design - can at times reach significant levels and could lead to damage of plant components or could reduce component lifetime significantly. Such a problem can arise for overload as well as for part load operation of the turbine. This paper discusses an approach to analyze the overload high pressure oscillation problem using computational fluid dynamic (CFD) modeling of the hydraulic machine combined with a network modeling technique of the hydraulic system. The key factor in this analysis is the determination of the overload vortex rope volume occurring within the turbine under the runner which is acting as an active element in the system. Two different modeling techniques to compute the flow field downstream of the runner will be presented in this paper. As a first approach, single phase flow simulations are used to evaluate the vortex rope volume before moving to more sophisticated modeling which incorporates two phase flow calculations employing cavitation modeling. The influence of these different modeling strategies on the simulated plant behavior will be discussed.

Do the CIS member states share foreign policy preferences?

Flemming Splidsboel Hansen 한양대학교 아태지역연구센터 2015 Journal of Eurasian Studies Vol.6 No.1

Relying on a large quantitative data set from the United Nations General Assembly voting records in the years 1992–2013, this study analyses developments in the foreign policy preferences of the member states of the Commonwealth of Independent States [CIS]. It finds that the general level of disagreement between the member states as a whole has increased significantly and that policies have become more radicalised, causing member states to hold directly opposing views still more often. It also finds that a majority of member states, led by Russia, have converged on the foreign policy mean, causing the core of the organisation to become still denser. This suggests that the CIS will undergo a future development where member states will travel along increasingly different trajectories. This research has important implications for our understanding of the CIS and of the policies of the individual member states.

Integration in the post-Soviet space

Flemming Splidsboel Hansen 한국외국어대학교 국제지역연구센터 2013 International Area Studies Review Vol.16 No.2

Established in 1991, the Commonwealth of Independent States (CIS) is still struggling to define a clear and commonly accepted identity for itself. As the member states hold very different views of the future CIS, they pull the organization in different directions, giving it a somewhat fuzzy character. While the Russian-led core is seeking closer integration, possibly even a transfer of decision-making to the supranational level, another group of states is insisting that the CIS should remain a loose and non-binding forum for cooperation. As a reflection of this reality, the CIS space is home to a number of other organizations which all take their members from the CIS circle. These organizations deliver what the CIS as a whole—because of its lowest common denominator policy—cannot do. The host of acronyms offer something to most member states,but they also cause the CIS space to be highly fragmented. Russia, in particular, has worked to bring all the different parts of the CIS closer together under its own leadership, but has remained largely unsuccessful. With its most recent initiative, a Eurasian Economic Union to be established by 2015, Russia is making a new effort to achieve what has failed so far. Little suggests that it will have any greater success now than before, and it therefore seems likely that the CIS will remain in the future also a complex organizational setting and a difficult challenge for Russia to handle.

Two-Way Coupled Fluid Structure Interaction Simulation of a Propeller Turbine

Schmucker, Hannes,Flemming, Felix,Coulson, Stuart Korean Society for Fluid machinery 2010 International journal of fluid machinery and syste Vol.3 No.4

During the operation of a hydro turbine the fluid mechanical pressure loading on the turbine blades provides the driving torque on the turbine shaft. This fluid loading results in a structural load on the component which in turn causes the turbine blade to deflect. Classically, these mechanical stresses and deflections are calculated by means of finite element analysis (FEA) which applies the pressure distribution on the blade surface calculated by computational fluid dynamics (CFD) as a major boundary condition. Such an approach can be seen as a one-way coupled simulation of the fluid structure interaction (FSI) problem. In this analysis the reverse influence of the deformation on the fluid is generally neglected. Especially in axial machines the blade deformation can result in a significant impact on the turbine performance. The present paper analyzes this influence by means of fully two-way coupled FSI simulations of a propeller turbine utilizing two different approaches. The configuration has been simulated by coupling the two commercial solvers ANSYS CFX for the fluid mechanical simulation with ANSYS Classic for the structure mechanical simulation. A detailed comparison of the results for various blade stiffness by means of changing Young's Modulus are presented. The influence of the blade deformation on the runner discharge and performance will be discussed and shows for the configuration investigated no significant influence under normal structural conditions. This study also highlights that a two-way coupled fluid structure interaction simulation of a real engineering configuration is still a challenging task for today's commercially available simulation tools.

Compression and truncation

Hyesun Cho,Edward Flemming 한국음운론학회 2015 음성·음운·형태론 연구 Vol.21 No.2

Compression and truncation are two general strategies adopted by languages in realizing tonal melodies in the face of time pressure. Compression involves adjustment of the phonetic details of tone realization to fit a tone sequence in the time available, while truncation involves deletion of a phonological tone, reducing a melody to fit the segmental material with which it must be associated. Seoul Korean appears to show truncation of tones in response to time pressure resulting from fast speech rate: the Accentual Phrase (AP) is canonically marked by a rise-fall-rise melody (LHLH), but at fast speech rates, APs can be realized with a rising F0 contour. Categorical tone deletion conditioned by speech rate would be theoretically significant because it would imply that a phonological operation can be conditioned by utterance-specific phonetic detail. However, analysis of the realization of the AP melody across a range of speech rates provides evidence that the apparent deletion of tones is actually the end result of compressing the final HLH sequence into such a short interval that the low tone is completely undershot and the two high tones are effectively merged. This analysis illustrates the general point that it is not possible to determine what phonological representation gave rise to a particular phonetic form without explicit analysis of the process of phonetic implementation.

덴마크 고용서비스의 시장화

Karen N. Breidahl,Flemming Larsen 한국노동연구원 2018 국제노동브리프 Vol.16 No.12

Numerical simulations of the internal flow pattern of a vortex pump compared to the Hamel-Oseen vortex

Angela Gerlach,Enrico Preuss,Paul Uwe Thamsen,Flemming Lykholt-Ustrup 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.4

We did a numerical study of the internal flow field of a vortex pump. Five operating points were considered and validated through a measured characteristic curve. The internal flow pattern of a vortex pump was analyzed and compared to the Hamel-Oseen vortex model. The calculated flow field was assessed with respect to the circumferential velocity, the vorticity and the axial velocity. Whereas the trajectories of the circumferential velocity were largely in line with the Hamel-Oseen vortex model, the opposite was true for vorticity. Only the vorticity at strong part load was in line with the predictions of the Hamel-Oseen vortex model. We therefore compared the circumferential velocity and vorticity for strong part load operation to the analytical predictions of the Hamel-Oseen vortex model. The simulated values were below the analytical values. The study therefore suggests that a vortex similar to the Hamel-Oseen vortex is only present at the strong part load operation.

Oscillation Mud-Ripples : Field Observations and their Significance

Tae Soo Chang,Burghard W. Flemming 대한지질학회 2006 대한지질학회 학술대회 Vol.2006 No.

조간대에서 발견되는 니질 파랑 연흔

장태수(Tae Soo Chang),Burghard W. Flemming 대한지질학회 2013 대한지질학회 학술대회 Vol.2013 No.10

The emerging role of lncRNAs in inflammatory bowel disease

Reza Yarani,Aashiq H. Mirza,Simranjeet Kaur,Flemming Pociot 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

Dysregulation of long noncoding RNA (lncRNA) expression is linked to the development of various diseases. Recently, an emerging body of evidence has indicated that lncRNAs play important roles in the pathogenesis of inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative Colitis (UC). In IBD, lncRNAs have been shown to be involved in diverse processes, including the regulation of intestinal epithelial cell apoptosis, association with lipid metabolism, and cell–cell interactions, thereby enhancing inflammation and the functional regulation of regulatory T cells. In this review, we aim to summarize the current knowledge regarding the role of lncRNAs in IBD and highlight potential avenues for future investigation. We also collate potentially immune-relevant, IBD-associated lncRNAs identified through a built-by association analysis with respect to their neighboring protein-coding genes within IBDsusceptible loci. We further underscore their importance by highlighting their enrichment for various aspects of immune system regulation, including antigen processing/presentation, immune cell proliferation and differentiation, and chronic inflammatory responses. Finally, we summarize the potential of lncRNAs as diagnostic biomarkers in IBD.