No abstract available

No abstract available

[en] In liquid flow calibration facilities run in the flying-start-and-finish operation mode, a diverter represents an essentially accuracy-determining functional unit, both with gravimetric and volumetric reference-based installations. Model-based approaches that describe a diverter's operation on the basis of realistic diverter flow conditions and kinematics of the diverting edge provide capabilities to take into account component-related and flow-related effects and processes for both a comprehensive diverter operation and an uncertainty analysis model. Based upon this dedicated knowledge of a special diverter design, this approach is applicable even if there is only minimum information on diverter characteristics available with worst-case assumptions being applied

[en] To clarify some of the governing phenomena and fundamental concepts involved in the wetting process, the physical models and wetting mechanisms for four different types of flow are theoretically, experimentally or qualitatively analyzed and a film flow regime map proposed. The investigation indicates that the wetting behavior and wetting mechanisms for different types of liquid flow are distinct and separate, and that the analytical treatments should be conducted individually for different circumstances. This discussion presents several new concepts, and not only clarifies the fundamental phenomena, but also provides further insight into the mechanisms which govern the wetting of hot surfaces. (author)

[en] A fuel assembly is described with coolant deflecting vanes which effect a vortex shaped coolant flow pattern. When assembled into a core, said fuel assemblies provide improved heat transfer and lower temperature gradients between all regions of the reactor core. (E.C.B.)

No abstract available

[en] Process for cooling the vessel of a nuclear reactor, the core of which is immersed in a liquid in contact with a blanket gas, by uptake of the cooled fluid flow feeding the reactor, whereby after having circulated the fluid uptake between the vessel and a concentric liner to the vessel up to the upper level, the fluid taken up to the lower level of the fluid contained inside the liner is discharged via means to maintain the flow of the fluid discharged at fluvial rate

[en] This investigation focuses on the numerical and experimental analysis of the 3D free surface flow in a Pelton turbine. In particular, two typical flow conditions occurring in a full scale Pelton turbine - a configuration with a straight inlet as well as a configuration with a 90 degree elbow upstream of the nozzle - are considered. Thereby, the effect of secondary flow due to the 90 degree bending of the upstream pipe on the characteristics of the jet is explored. The hybrid flow field consists of pure liquid flow within the conduit and free surface two component flow of the liquid jet emerging out of the nozzle into air. The numerical results are validated against experimental investigations performed in the laboratory of the Institute of Fluid Mechanics (FLM). For the numerical simulation of the flow the in-house unstructured fully parallelized finite volume solver solver3D is utilized. An advanced interface capturing model based on the classic Volume of Fluid method is applied. In order to ensure sharp interface resolution an additional convection term is added to the transport equation of the volume fraction. A collocated variable arrangement is used and the set of non-linear equations, containing fluid conservation equations and model equations for turbulence and volume fraction, are solved in a segregated manner. For pressure-velocity coupling the SIMPLE and PISO algorithms are implemented. Detailed analysis of the observed flow patterns in the jet and of the jet geometry are presented.

[en] The equipment described consists of a vessel in which an electric igniter with a tracer medium filling are sealed with a plug. The plug is secured in the vessel mouth using a safety fuse. The vessel is made of a shatterable material. In the described equipment the tracer substance is mixed with a liquid more rapidly and completely than when the existing methods are used. The application of a radioactive tracer increases safety of work and facilitates handling in the preparation of dosage. The electric ignition can be initiated at an accurately defined time and from any distance. The dosing device can also be used in awkward places. (J.B.)

[en] The study of luquid discharge is based on mechanical and thermodynamical analysises. Unfortunately, they lead to dischange equations which don't describe the phenomenon in unsaturated porous medium, mainly during the first moment of the liquid dischange. We have imagined an experimental system in view to overcome this difficulty. With this system we have measured the flow dischange during the first time of the phenomenon. Owing to the solution of classical equations of liquid dischange, this value is equal to infinity, but in our case we have found that the later is equal to zero. Generally, the underformation of hydrous profiles during filtration is used in order to simplify and resolve classical equation of liquid discharge. But the use of gamma radiation has shown that this hypothesis is not valid