Wyniki wyszukiwania - BazTech

1

Heat transfer enhancement from a heated plate with hemispherical convex dimples by forced convection along with a cross flow jet impingement

Patro P., Garnayak S.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 1

127--141

EN

In the present study, heat transfer from a small three dimensional rectangular channel due to turbulent jet impinging from a nozzle normal to the main flow at the inlet has been investigated. Hemispherical convex dimples are attached to the bottom plate from where heat transfer calculations are to be performed. Numerical simulations were performed using the finite volume method with […] turbulence model. The duct and nozzle Reynolds number are varied in the range of […], respectively. Different nozzle positions (X/D = 10.57, 12.88, 15.19) along the axial direction of the rectangular duct have been considered. It has been found that higher heat transfer is observed at X/D = 10.57 as compared to the other positions. The heat transfer enhancements with and without cross-flow effects have also been compared. It has been shown that the heat transfer rate with cross-flow is found to be much higher than that without crossflow. Also, the effect of dimples on the heated surface on heat transfer was investigated. The heat transfer is found to be greater in the presence of a dimpled surface than a plane surface.

2

Effect of fan arrangement and air flow direction on thermal performance of radiators in a power transformer

Paramane S. B., Van der Veken W., Sharma A., Coddé J.

Journal of Power Technologies

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2017

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Vol. 97, nr 2

127--134

EN

The focus of the present numerical work is to study the effect of fan air flow direction and mounting arrangement on the thermal performance of the radiators of power transformers using Computational Fluid Dynamics analysis. The study is carried out for four radiators of 3 m height and 30 fins with 0.52 m width and two fans of 1 m diameter in vertical and horizontal air flow directions. The horizontal flows from the two fans are considered in the same and the opposite direction, with the fans located on the same and the opposite side, respectively running at the same speed of 860 rpm for all configurations. Thermal radiation is modelled using the discrete transfer radiation model. A comparison of different flow and heat transfer patterns as well as heat dissipation - for the four different configurations - is presented. Velocity and temperature contours are used to visualize the heat and fluid flow distribution over the radiators. Fans placed on one side of the radiators result in larger heat dissipation than the other arrangements studied. The reasons for the improvement in heat dissipation are presented.

3

Instalacje membranowe typu "cross flow"

Suchecka T., Szwast M., Piątkiewicz W.

Wodociągi - Kanalizacja

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2011

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nr 9

44-47

4

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.

5

Large-scale structures forming in a cross flow : particle image velocimetry conditional analysis

Camussi R., Stella A., Guj G., Kowalewski T. A.

Machine Graphics and Vision

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1999

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Vol. 8, No. 4

579-595

EN

A conditional Particle Image Velocimetry (PIV) acquisition technique and averaging procedure are developed to study coherent structures formed by the interaction between a jet and a cross-stream. The experiment is constructed in a water tunnel, the water transversal jet is perturbed by a mechanical device. Measurements are performed at reynolds number 100 and cross-flow velocity ratio ranging from 2.0 to 4.5. Sequences of images are acquired synchronously to the perturbation so that a statistical process may be applied to obtain average velocity and vorticity in a selected cross-section of the flow. The averaged fields and the instantaneous images together with flow visualizations by Laser Induced Fluorescence (LIF) technoque are used to interpret behaviour of the large-scale vortices generated in the cross-flow experiment.