Modeliranje atmosferskog graničnog sloja u klimatskom zračnom tunelu

Ribičić, Matko (2015) Modeliranje atmosferskog graničnog sloja u klimatskom zračnom tunelu. = Atmospheric boundary layer modeling in the climatic wind tunnel. Master's thesis (Bologna) , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Kozmar, Hrvoje and Pospišil, Stanislav.

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Abstract (Croatian)

Eksperimenti su provedeni u klimatskom zračnom tunelu s ciljem određivanja utjecaja nazubljene barijere, generatora vrtloga i podne hrapavosti na karakteristike strujanja zraka i modeliranog atmosferskog graničnog sloja budući da je precizno eksperimentalno modeliranje atmosferskog strujanja zraka i turbulencije u zračnom tunelu glavni preduvjet kod ispitivanje djelovanja vjetra na građevinske objekte i vozila. Provedena su opsežna mjerenja brzine strujanja zraka, tlaka i temperature uz korištenje užarene žice, Prandtl-Pitotove cijevi i termometra. Rezultati mjerenja su prikazani kao profili vremenski osrednjene brzine, intenziteta turbulencije i turbulentnih duljinskih skala, kao i spektralne raspodjele kinetičke energije turbulencije. Poseban naglasak je na razvoju i jednolikosti strujanja zraka na različitim pozicijama u zračnom tunelu, kao i stabilnost simulacije atmosferskog graničnog sloja na poziciji na kojoj se u zračnom tunelu uobičajeno postavljaju i ispituju strukturni modeli. Barijera uzrokuje smanjenje osrednjene brzine strujanja i povećanje turbulencije blizu podloge, generatori vrtloga pospješuju povećanje turbulencije po cjelokupnoj ispitivanoj visini od podloge, dok je povećanje turbulencije i smanjenje brzine strujanja uslijed djelovanja podne hrapavosti ograničeno na sloj neposredno iznad podloge. Uspješno je generiran model atmosferskog graničnog sloja karakterističan za strujanje vjetra i turbulenciju iznad prigradskog/gradskog tipa terena. Mjerilo simulacije atmosferskog graničnog sloja ostvarenog mjerenjima iznosi 1:300, a eksperimentalni rezultati se dobro podudaraju s prethodnim istraživanjima, međunarodnim propisima i standardima. Modelirani atmosferski granični sloj je razvijen i jednolik u uzdužnom i poprečnom smjeru na poziciji na kojoj se uobičajeno postavljaju i ispituju strukturni modeli.

Abstract

Experiments are carried out in the climatic wind tunnel to investigate the influence of castellated barrier wall, vortex generators and surface roughness on flow characteristics and the simulated atmospheric boundary layer, as precise modeling of atmospheric flow and turbulence in the wind tunnel is a key prerequisite when studying wind effects on structures and vehicles. Extensive measurements were carried out to determine flow velocity, pressure and temperature using hot wire, Prandtl-Pitot tube, pressure sensors and thermometers. Experimental results were reported as profiles of mean flow velocity, turbulence intensity and turbulent length scales, as well as power spectral density of velocity fluctuations. A particular focus was on flow development and uniformity at various positions in the wind-tunnel test section, as well as characteristics of the atmospheric boundary layer simulations at the turntable. The barrier was observed to cause a decrease in flow velocity and an increase in the turbulence close to the surface, vortex generators enhance turbulence throughout the entire height range under scope, while an increased turbulence and a decreased flow due to surface roughness is exhibited close to surface. The atmospheric boundary layer is successfully simulated for suburban/urban type of terrain. The simulation length scale is 1:300. Experimental results are in good agreement with previous studies, international standards and codes. The simulated atmospheric boundary layer is developed and uniform at the turntable.

Item Type: Thesis (Master's thesis (Bologna))
Uncontrolled Keywords: Eksperimentalna aerodinamika okoliša; atmosferski granični sloj; turbulencija, simulacije u zračnom tunelu; Counihanova metoda; mjerenje brzine, tlaka i temperature;
Keywords (Croatian): Experimental environmental aerodynamics; Atmospheric boundary layer; Turbulence; Wind-tunnel experiments; Counihan method; Velocity, pressure and temperature measurements;
Subjects: TECHNICAL SCIENCE > Mechanical Engineering
Divisions: 500 Department of Energy, Power Engineering and Environment > 520 Chair of Fluid Mechanics
Date Deposited: 26 Nov 2015 13:12
Last Modified: 27 Nov 2017 06:00
URI: http://repozitorij.fsb.hr/id/eprint/4914

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