Wyniki wyszukiwania - BazTech

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Thermal and hydraulic phenomena in boundary layer of minijets impingement on curved surfaces

Kura T., Fornalik-Wajs E., Wajs J.

Archives of Thermodynamics

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2018

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Vol. 39, no 1

147--166

EN

Presented work considers flow and thermal phenomena occurring during the single minijet impingement on curved surfaces, heated with a constant heat flux, as well as the array of minijets. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted, regarding single phase and two-phase simulations. Focus was placed on the proper model construction, in which turbulence and boundary layer modeling was crucial. Calculations were done for various inlet parameters. Initial single minijet results served as the basis for the main calculations, which were conducted for two jet arrays, with flat and curved heated surfaces. Such complex geometries came from the cooling systems of electrical devices, and the geometry of cylindrical heat exchanger. The results, regarding Nusselt number, heated surface temperature, turbulence kinetic energy, production of entropy and vorticity, were presented and discussed. For assumed geometrical parameters similar results were obtained.

2

On numerical modelling of heat transfer and fluid flow in a scraped surface heat exchanger

Błasiak P., Gnutek Z.

Archives of Thermodynamics

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2014

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Vol. 35, no. 3

251--264

EN

Steady state two-dimensional numerical simulation of laminar heat transfer and fluid flow in a scraped surface heat exchanger (SSHE) is presented. Typical SSHE consists of a stator, rotating shaft and scraping blades. Due to symmetry only a quarter of the heat exchanger is modelled. Governing equations for transport of mass, momentum and energy are discretised and solved with the use of commercial CFD code. The results are presented in a nondimensional form for velocity, pressure and temperature distributions. Local and averaged Nusselt number along the stator wall are calculated and depicted in graphs. It was found that the thirty fold increase of the cReynolds number, leads to heat transfer enhancement rate by three times.

3

Analiza eksperymentalna wpływu strug uderzających pod działaniem przepływu krzyżowego na wymianę ciepła

Fornalik E.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2000

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nr 117, vol. 2

195-200

PL

W pracy zaprezentowano wyniki badań wpływu strug uderzających pod działaniem przepływu krzyżowego na wymianę ciepła oraz oddziaływania między strugami. Temperatura powierzchni ścianki, na którą oddziaływały strugi, była mierzona za pomocą cienkiej warstwy ciekłego kryształu. Kolorowe zdjęcia powierzchni ciekłego kryształu zostały jakościowo i ilościowo przetworzone w celu uzyskania rozkładu liczby Nusselta na powierzchni ścianki. Dokonano również wizualizacji struktury przepływu za pomocą barwnika fluorescencyjnego dodanego do przepływającego przez dysze medium oraz światła lasera.

EN

Visualization of heat transfer enhancement regions and flow structure were made for a pair of jets obliquely discharged into a crossflow. The examination of interaction between the two oblique jets were provided. The temperatures of the target surface were visualized with thermochromic liquid crystal sheets. The colors of the liquid crystal images taken by a CCD camera were transformed accurately and effectively into the temperatures by means of the neural network. Fluorescent dyes were added to the jets' fluid to visualize the cross-sectional flow patterns with the light sheet of a laser.