Stability behaviour and dynamic response of cooling towers subjected to wind loading

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dc.contributor.advisorZingoni, Alphoseen_ZA
dc.contributor.authorKucherera, Grant Tarwireien_ZA
dc.date.accessioned2017-05-16T07:55:27Z
dc.date.available2017-05-16T07:55:27Z
dc.date.issued2016en_ZA
dc.description.abstractIn this study, a linear eigenvalue buckling parametric analysis is presented for various cooling tower shell geometries. The shells are subjected to increasing wind pressures (speeds) to observe the trends in the critical buckling pressures/speeds at which the shell first buckles and the corresponding buckling modes. The cooling tower's geometry is changed in a systematic manner to obtain the relationship between critical wind speeds associated with the first mode of buckling and the cooling tower's geometry. Geometrical parameter ratios of the cooling tower's dimensions are considered in order to cover a wider spectrum of the cooling tower's geometry. The critical wind speed versus height curve is observed to be similar to the Euler buckling curve. There appears to be a certain optimum throat height to total height ratio of about 0.75 for any cooling tower at which the critical wind speed is maximum. The critical wind speed varies linearly with the cooling tower thickness and non-linearly with all diameter ratios. A linear eigenvalue vibration parametric analysis is presented for various cooling tower shell geometries to observe trends in the free vibration response (natural frequencies and mode shapes). The forced response of the cooling tower to various forcing frequencies of wind gusts is analysed using the mode superposition method. The shells are subjected to increasing wind gust periods of the same speed to obtain the trends in the forced vibration response (response frequencies and modes). The cooling tower's geometry is changed in a systematic manner to obtain the free and forced vibration behaviour. The natural frequencies and their corresponding bandwidths for the first ten different modes reduce with increasing height. They are generally invariant with the height to top diameter ratio, but the bandwidth increases with increasing height to top diameter ratio. The response frequencies and their corresponding bandwidths generally decrease with increasing height as well as the height to top diameter ratios. The response frequency generally decreases with decreasing forcing frequency, but not for all the cooling tower geometries. The findings can be used as a basis for further research and establishment of conceptual design guidelines when considering stability, free and forced vibration cooling tower behaviour.en_ZA
dc.identifier.apacitationKucherera, G. T. (2016). <i>Stability behaviour and dynamic response of cooling towers subjected to wind loading</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering. Retrieved from http://hdl.handle.net/11427/24305en_ZA
dc.identifier.chicagocitationKucherera, Grant Tarwirei. <i>"Stability behaviour and dynamic response of cooling towers subjected to wind loading."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 2016. http://hdl.handle.net/11427/24305en_ZA
dc.identifier.citationKucherera, G. 2016. Stability behaviour and dynamic response of cooling towers subjected to wind loading. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Kucherera, Grant Tarwirei AB - In this study, a linear eigenvalue buckling parametric analysis is presented for various cooling tower shell geometries. The shells are subjected to increasing wind pressures (speeds) to observe the trends in the critical buckling pressures/speeds at which the shell first buckles and the corresponding buckling modes. The cooling tower's geometry is changed in a systematic manner to obtain the relationship between critical wind speeds associated with the first mode of buckling and the cooling tower's geometry. Geometrical parameter ratios of the cooling tower's dimensions are considered in order to cover a wider spectrum of the cooling tower's geometry. The critical wind speed versus height curve is observed to be similar to the Euler buckling curve. There appears to be a certain optimum throat height to total height ratio of about 0.75 for any cooling tower at which the critical wind speed is maximum. The critical wind speed varies linearly with the cooling tower thickness and non-linearly with all diameter ratios. A linear eigenvalue vibration parametric analysis is presented for various cooling tower shell geometries to observe trends in the free vibration response (natural frequencies and mode shapes). The forced response of the cooling tower to various forcing frequencies of wind gusts is analysed using the mode superposition method. The shells are subjected to increasing wind gust periods of the same speed to obtain the trends in the forced vibration response (response frequencies and modes). The cooling tower's geometry is changed in a systematic manner to obtain the free and forced vibration behaviour. The natural frequencies and their corresponding bandwidths for the first ten different modes reduce with increasing height. They are generally invariant with the height to top diameter ratio, but the bandwidth increases with increasing height to top diameter ratio. The response frequencies and their corresponding bandwidths generally decrease with increasing height as well as the height to top diameter ratios. The response frequency generally decreases with decreasing forcing frequency, but not for all the cooling tower geometries. The findings can be used as a basis for further research and establishment of conceptual design guidelines when considering stability, free and forced vibration cooling tower behaviour. DA - 2016 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2016 T1 - Stability behaviour and dynamic response of cooling towers subjected to wind loading TI - Stability behaviour and dynamic response of cooling towers subjected to wind loading UR - http://hdl.handle.net/11427/24305 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/24305
dc.identifier.vancouvercitationKucherera GT. Stability behaviour and dynamic response of cooling towers subjected to wind loading. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 2016 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/24305en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Civil Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherCivil Engineeringen_ZA
dc.titleStability behaviour and dynamic response of cooling towers subjected to wind loadingen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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