A Comparative CFD–PIV Analysis of a Stirred Tank Equipped with a Rushton and a Pitched Blade Turbine

Abstract This study presents the hydrodynamic behavior of a dual‐stage stirred tank, which is typically used in bioprocesses and is equipped with a Rushton turbine (RT) below and a pitched blade turbine (PBT) above. The investigation of the turbulent flow is based on numerical simulations (computational fluid dynamics, CFD) and experiments (particle image velocimetry, 2D–2C PIV). Direct CFD–PIV comparisons in dual‐impeller tanks are rare. The velocity and turbulent kinetic energy vertical profiles show a high degree of agreement between the CFD and PIV data across the entire tank at 250 rpm. The power consumption calculated by CFD for the RT accounts for 78 % of the global power number. CFD post‐processing confirms the presence of a pair of trailing vortices behind the RT only, with local velocities exceeding the tip speed.