Towards Accurate Computations of Active Stabiliser Fins, focusing on Dynamic Stall

Steps towards accurate and efficient characterisation of the hydrodynamic behaviour of active stabiliser fins have been conducted using computational fluid dynamics. Conditions seen at hydrodynamic testing facilities (Reynolds number = 135,000), with an angle of attack variation described as α(t) = 10° + 15° sin(ωt) have been modelled in two dimensions with various RANS turbulence models (k-ω SST, k-√kl, Spalart-Allmaras & LCTM) for reduced frequencies k=0.1 & 0.05. Solutions were compared to experimental results and results from other calculation methods (LES) and to results from a typical sea keeping code. The results showing the hysteresis loop for C_L and C_D show that a good agreement was seen to the literature. For seakeeping applications, moderate refinement in time and space is sufficient, and that the k-ω SST turbulence model best matches the C_L and C_D curves found in the literature. The increased knowledge of stabiliser fins dynamics will be used to improve time-domain seakeeping codes and possible also the control laws for active stabilizer fins.