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The Design and Aerodynamic Testing of DPIK Probe
Procházka, Pavel P. ; Barraclough, V. ; Skála, Vladislav ; Uruba, Václav
The isokinetic probe used to detect the liquid phase drift from the cooling tower is presented here. The main motivation is costs reduction that arises during standard drift measurements. The probe was developed in the framework of the grant project between private company 4Jtech and Institute of Thermomechanics. The aerodynamic design and optimization of this probe should fulfill one important criterion – to capture the droplets from the drift with maximal efficiency. Kalorimetric principle is then used to evaluate the amount of trapped water. Standard PIV (Particle Image Velocimetry) measurement technique and modified IPI (Interferometric Particle Imaging) methods were used to measure the flow field topology and the particle size distribution, respectively.
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Wake Behind a Cylinder: An Overview of Spatio-Temporal Aspects
Uruba, Václav
A circular cylinder in crossflow is subjected to the overview study from the point of view spatial and temporal characteristics. It represents itself a typical engineering problem, appearing in practice frequently in various forms. In fluid mechanics, this case is considered to be a typical canonical case, with relatively simple and straightforward definition, but complex and dynamical flow topology. The typical dynamics is characterized by quasi-periodic behavior called von Kármán – Bénard vortex street with a typical frequency expressed in dimensionless number called Strouhal number. The wake flow structure is considered to be characterized by a single frequency and 2D topology, homogeneous along the cylinder axis, very often. The presented paper concentrates on differences between this commonly accepted model and physical reality. Both temporal and spatial aspects of the flow in the wake behind a cylinder are to be addressed. The turbulent subcritical wake characterized by Reynolds number about 5 thousand will be considered, as this situation is a typical case in mechanical engineering applications.
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Výpočty výměníku mezi primárním okruhem a meziokruhem malého modulárního reaktoru DAVID
Kobylka, D. ; Hrubý, Jan ; Kordík, Jozef ; Gabriel, Dušan ; Marek, René ; Isoz, Martin
The report summarizes the joint results of the Department of Nuclear Reactors FNSPE, CTU and IT CAS, in the area of thermal and hydraulic calculations of the heat exchanger between the primary and intermediate circuits of the developed small modular reactor (SMR) DAVID. The assignment parameters were further specified during control days and with updated documentation. During the analysis of the initial system parameters, it was found that the original geometric configuration of the exchanger had a completely insufficient surface for heat transfer. A decision was made, several parameters were modified and based on a series of calculations using two independent simplified models, a reasonable configuration with a significantly smaller diameter of the tubes in a significantly larger number was chosen. The pressure losses on both sides of the heat exchanger are within normal ranges and will not cause problems with the construction of these circuits. Although there are differences between the results from both used models, their comparison shows that the chosen different calculation methods lead to approximately the same results and the models do not show fundamental errors.
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Improving computational efficiency of contact solution in fully resolved CFD-DEM simulations with arbitrarily-shaped solids
Studeník, Ondřej ; Kotouč Šourek, M. ; Isoz, Martin
The abundance of industrial processes containing both solid and liquid phases generate demand for fully resolved models allowing for detailed analysis and optimization of these processes. An established approach providing such models is based using a variant of an immersed boundary method to couple the computational fluid dynamics (CFD) and discrete element method (DEM). In the talk, we will present our custom and monolithic implementation of a fully-resolved CFDDEM solver and concentrate on the intricacies of solving contact between two arbitrarily-shaped solids. We shall propose an efficient contact treatment based on the concept of a virtual mesh, which provides the mesh resolution required by DEM through dividing the space around the contact point in a finite volume fashion without any changes to the CFD mesh itself. A substantial part of the talk will devoted to the parallelization of the contact solution, especially in the context of the domain decomposition method imposed by the CFD solver.
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Measurements on Turbine Cascade KOBRA
Luxa, Martin ; Hála, Jindřich ; Šimurda, David
The report contains results and evaluation of aerodynamic measurement on a blade cascade representing the section imitating the conical stream line in the last rotor row of a gas trubine under considerable off-design condition. The research report contains detailed specifications of the measured model, overview of the results of the optical measurements (interferometry, schlieren method in Toepler configuration) and pneumatic measurements (traversing with five hole conical probe downstream the cascade).
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