Experimental and numerical study of the non-uniform total temperature in a turbulent Mach 0.6 vortex street

This work investigates the non-uniform total temperature and total pressure downstream of a circular cylinder in transonic flow. At Mach 0.6 shock induced separation of the flow occurs from the surface of the cylinder. The unsteady shear layers roll up into vortices that are shed from the cylinder forming a von Kármán vortex street of convecting vortices. An experimental investigation of the vortex street is carried out at a distance of six cylinder diameters downstream. Time resolved total temperature measurements reveal the presence of localised ‘hot spots’ of increased total temperature at the edges of the wake and localised ‘cold spots’ of decreased total temperature along the centre of the wake. The experimental measurements are compared against a concurrent numerical study using a time accurate numerical model with turbulence closure. The numerical model also captures the non-uniform total temperature and total pressure distribution downstream of the cylinder. The non-uniform total temperature and total pressure distribution is shown to be a source of entropy production. Comparison of the total temperature and total pressure distribution highlights the influence of the boundary layer development and separation characteristics on the vortex shedding and energy separation processes. This emphasizes the importance of including the effects of turbulence and boundary layer development in numerical studies of the energy separation downstream of circular cylinders.