An insight into in quasi two-dimensional flow features over turbine blading from the works of Jonathan Paul Gostelow

The flow through the predominantly two-dimensional geometries of cascades of blades is intrinsically three-dimensional and unsteady. Direct Numerical Simulation, Large Eddy Simulations, and time-resolved Particle Image Velocimetry resolve the full flow physics, relevant to aerodynamic loss and heat management. Such studies build upon earlier insight drawn from quasi two-dimensional investigations that identified the key areas where progress in understanding was most needed. These areas stretch across the full passage, from the leading edge of the blade to the passage outflow. Streamwise surface vorticity, transition, the calmed region, shock-boundary layer interaction, and vortex shedding are considered in detail, specifically (i) on what gaps in their physical understanding the works of Jonathan Paul Gostelow exposed and (ii) what gaps were present in the two-dimensional computational approaches used to represent these flows in these works. These useful insights are obtained from the geometrically simpler settings of circular cylinders in cross-flow and from flat plate experiments, as well as from cascades of blades. This paper presents an overview of the physical understanding of the flow features that underpins the more recent time-resolved three-dimensional investigations, led by the late Emeritus Professor Jonathan Paul Gostelow. This work celebrates some of Paul Gostelow's 50+ years of turbomachinery research achievements and develops awareness about their significance towards reaching a more complete knowledge of the flow physics in turbomachinery, using the more recent time-resolved three-dimensional modelling capability of Computational Fluid Dynamics software.