How much a geometrical model of a honeycomb seal can be simplied in the CFD calculation

This paper presents the influence of geometry simplification on the results obtained in the computational fluid dynamics simulation. The subject of simulation was part of the honeycomb seal located at the inlet to high pressure part of a steam turbine. There were three diferent geometrical models assumed in the calculations. First one was two-dimensional case and two others were three-dimensional, one with the radius of curvature and one without. Numerical simulations were performed for 15 sets of boundary conditions to compare flow characteristics for each geometrical case

Modeling of a mixture flow of helium and methanol in thermocatalytic reactor and chemical reactions on the intermethallic phase of Ni3A

In this paper, the specified issues that occurs in the numerical modeling of complex phenomena of chemical reactions intensified with forced fluid flow in the thermocatalytic reactor channels on the intermetallic phase of Ni3Al are presented. Based on the example of flowing mixture containing helium contaminated by methanol in a horizontal microchannels, heated from the outside, received results of the experiment were shown and compared with computational fluid dynamize calculations. However, standard version of commercial code have been expanded by user definedfunctions. These extensionstransformed the calculation mechanisms and algorithms of computational fluid dynamize codes adapting them for the micro-flow cases and increased chemical reactions rate on an interphase between fluid and solid. Results obtained on the way of numerical calculations were compared with experimental data receiving satisfactory compliance

Enhanced energy conversion as a result of fluid-solid interaction in micro- and nanoscale

It is known that nano- and micromechanics require new approaches to right describing of surface-like phenomena which lead to an enhanced energy conversion. In this work, a general form of surface forces that consist of a contribution from both the friction and mobility components has been extended to collect the effects of bulk and surface motion of a fluid. Quite similar impact can be observed for a solid-fluid mixture, where the principle of effective stress for this new type of approach should be considered from the very beginning. The second motivation of our work is to present the multiscale domain of fluid-solid interaction which describes some “emergence effects” for materials with especially high volumetric surface densities

Enhanced energy conversion as a result of fluid-solid interaction in micro- and nanoscale

It is known that nano- and micromechanics require new approaches to right describing of surface-like phenomena which lead to an enhanced energy conversion. In this work, a general form of surface forces that consist of a contribution from both the friction and mobility components has been extended to collect the effects of bulk and surface motion of a fluid. Quite similar impact can be observed for a solid-fluid mixture, where the principle of effective stress for this new type of approach should be considered from the very beginning. The second motivation of our work is to present the multiscale domain of fluid-solid interaction which describes some “emergence effects” for materials with especially high volumetric surface densities

Problem elastyczności bloków cieplnych w warunkach dynamicznego rozwoju OZE

The paper is an overview of selected ways of increasing the operational flexibility of steam units, which are predominant in the Polish power system. These studies were prompted by the dynamic changes in the structures of installed capacity and generation output in the National Power System due to a rapid increase in the number of wind turbines in the country. The methods of thermal unit operational flexibility improvement are divided into two groups. The first group comprises solutions with heat and mass storage as well as chemical energy storage. These are solutions to manage the auxiliary load of units regardless of system load. The second group consists of methods for an off-design increase in the safe level of thermal energy machine design stress. The development of numerical tools using complex methods of thermal stress determination, such as Burzyński-Pęcherski’s theory, combined with advanced on-line machine diagnostics, allows for an extension in the operational range of a machine, beyond the original safe operation limit without risk of damage or loss of service life, in other words.W pracy przedstawiono przegląd wybranych sposobów zwiększania elastyczności pracy bloków parowych, które stanowią największą siłę wytwórczą w polskim systemie elektroenergetycznym. Motywacją do podjęcia prac w tym kierunku są dynamiczne zmiany w strukturze mocy zainstalowanej i energii wytwarzanej w Krajowym Systemie Elektroenergetycznym związane z szybkim wzrostem liczby siłowni wiatrowych na terenie kraju. Metody poprawy elastyczności pracy bloków cieplnych podzielono na dwie grupy. Pierwszą grupę stanowią rozwiązania wykorzystujące magazyny ciepła i masy oraz magazyny energii chemicznej. Są to rozwiązania pozwalające kształtować obciążenie potrzeb własnych bloku niezależnie od obciążenia systemu. Drugą grupę stanowią metody pozwalające na pozaprojektowe wytężanie konstrukcji maszyn cieplnych. Rozwój narzędzi numerycznych wykorzystujących złożone metody wyznaczania naprężeń cieplnych, takie jak np. teoria Burzyńskiego–Pęcherskiego, w połączeniu z zaawansowanymi systemami diagnostyki maszyn online, umożliwiają wychodzenie z pracą maszyn poza granice tzw. bezpiecznej pracy bez ryzyka uszkodzeń lub utraty żywotności