In a complex offshore environment, wind load is among the most important design factors for the jack-up platform. In this study, we have conducted a detailed numerical analysis of wind loading on a jack-up platform in normal operation and extreme conditions at both model scale and full scale for wind headings from 0 to 360 degrees. The wind load in the form of coefficients of three force components and three moment components are in good agreement between numerical prediction and experimental measurements. In addition, we measured surface pressures at 22 different locations of the platform, and they match well with CFD calculations.
Being one of the typical types of Mobile Offshore Drilling Unit (MODU), the jack-up units are widely used in shallow to medium-deep water (i.e. up to 170 meters deep) all over the world. In such complex offshore operation environment, a jack-up platform is subject to both aerodynamic and hydrodynamic loads from wind, wave and current. Wind load is among the most important design load for the jack-up structure, especially due to much larger projected area above water than under water. Therefore, it is critical to meet design requirement of the wind load with respect to the safety, reliability and stability of jack-up platform in operation.
Traditionally, the wind load acting on offshore structures is measured in wind tunnel tests, but with rapid development in Computational Fluid Dynamics (CFD) and ever-increasing computing power, it is possible to simulate wind flow around the offshore structure and calculate wind loads numerically. However, good practice has to be followed in order to benchmark CFD modelling with wind tunnel test result well.
While significant effort has been made in numerical study of aerodynamic loading on offshore platforms in the past two decades, the offshore industry has begun using CFD as an alternative tool to predict wind load on offshore structures including Jack-ups, semi-submersibles and FPSOs (Jiang et al, 2013; Koop et al, 2010, 2012; Kim et al, 2018; Yeon et al, 2021; Liu et al, 2021; Zhang et al, 2021). As the oil fields continue to deplete, jack-up fleets are pushed towards deeper waters and harsher environments, more accurate and reliable wind load data are required from computational tools. The CFD data-based Reduced Order Methods (ROMs) enables investigation of wider range of scenarios and obtain the performance evaluations almost instantly (Xing et al, 2021, 2022).
