Modelling of fatigue due to thermal mixing by using a spectrum method

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    Abstract

    Turbulent mixing of cold and hot fluids can lead to high-cycle thermal fatigue in T-junctions, but modelling of the thermal load induced to the structure is challenging. The spectrum method has been recently proposed as an efficient modelling method, which uses a theoretical turbulence spectrum to represent the fluctuating thermal load. In this work, further development and application of the method is presented. Estimation of the frequency of the largest-scale temperature fluctuations is considered in particular, as this is an essential input parameter for the model spectrum. The method is applied to a T-junction including a mixer pipe and a high temperature difference that induces significant buoyancy effects. The frequency scale of the fluctuations is determined for the flow case based on temperature spectra obtained from a Computational Fluid Dynamics (CFD) simulation. A formula for the frequency scale is proposed, which can be used in approximating the frequency scale for other flow conditions. Fatigue and crack growth analysis of the T-junction wall are carried out by using the spectrum method, and the results are compared with those obtained with sinusoidal and CFD temperature loads. The results indicate improvement in accuracy over the highly simplified sinusoidal method.

    Original languageEnglish
    Title of host publicationProceedings of the ASME 2018 Pressure Vessels and Piping Conference
    Subtitle of host publicationDesign and Analysis
    PublisherAmerican Society of Mechanical Engineers ASME
    Number of pages10
    Volume3A
    ISBN (Electronic)978-0-7918-5162-3
    DOIs
    Publication statusPublished - 2018
    MoE publication typeNot Eligible
    EventASME 2018 Pressure Vessels and Piping Conference, PVP2018 - Hotel Hilton, Prague, Czech Republic
    Duration: 15 Jul 201820 Jul 2018
    Conference number: 52

    Conference

    ConferenceASME 2018 Pressure Vessels and Piping Conference, PVP2018
    Abbreviated titlePVP2018
    CountryCzech Republic
    CityPrague
    Period15/07/1820/07/18

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    Cite this

    Timperi, A. (2018). Modelling of fatigue due to thermal mixing by using a spectrum method. In Proceedings of the ASME 2018 Pressure Vessels and Piping Conference: Design and Analysis (Vol. 3A). [ PVP2018-84398] American Society of Mechanical Engineers ASME. https://doi.org/10.1115/PVP2018-84398