engleski

Numerical procedure for pre-swirl stator structural integrity evaluation

This paper presents the numerical procedure for Pre-Swirl Stator (PSS) structural design with emphasis on wave induced hydrodynamic loads. The procedure consists of three main steps: definition of Dominant Loading Parameter (DLP), long-term wave statistical analysis leading to Equivalent Design Waves (EDWs) and non-linear simulations of defined EDWs. DLP is defined using simplified lift force approximation for airfoil profile. Non- linearity in the DLP definition requires the time development of each contributing sea-state from the scatter diagram and analysis of the signal to obtain proper statistical parameters for further long-term estimations. In the long-term wave analysis, potential flow is used due to its efficiency compared to more complex CFD method. Non-linear EDW simulations are performed with the CFD/FEM coupling model for a more realistic estimation of the loads and stresses. Extreme response and fatigue are assessed in this work with detail verification and explanation of each step in the entire procedure. Potential flow is solved by means of HydroStar, CFD solution is obtained using open-source tool OpenFOAM and FEM solution is obtained by means of NASTRAN. Overall, the results show that the proposed method can reliably predict the maximum expected wave loads and proves the current design of analyzed PSS to satisfy the extreme response and fatigue criteria.

CFD–FEM ; Equivalent Design Wave ; Pre-Swirl Stator ; Fatigue

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