Forces acting on circular cylinders placed in a turbulent plane mixing layer

Abstract

Time-averaged pressure distributions along the surface of a circular cylinder placed in a turbulent plane mixing layer were measured in order to clarify the time-averaged aerodynamic forces acting on the cylinders, together with the flow patterns around them. The Reynolds number based on the diameter of the cylinder d and the mainstream velocity U outside the mixing layer was in the range (2.16–4.06) × 10 4. Both the angular position of the stagnation point and the stagnation-pressure coefficient were well correlated with a parameter d δ , δ being the width of the mixing layer, if the location of the cylinders was expressed in terms of the ratio u c U , where u c is the velocity of the otherwide undisturbed mixing layer at the centre of the cylinders. The drag coefficient was found to be rather insensitive to the parameter d δ , whereas a slight dependence of thedrag coefficient on the cylinder diameter was observed owing to the effect of turbulence in the mixing layer. The lift force was always directed from the high-velocity side to the low-velocity side of the mixing layer, its magnitude being approximately proportional to the parameter d δ .