Flow pass a rotating cylinder with end disk: PIV measurements and RANS computations
Conference contribution, 2012
Because of the increasing attention to fuel consumption and anticipated legislation, the Flettner rotor has attained renewed interest recently as an auxiliary ship propulsion device. To improve the understanding of the flow involved, the flow structure around a Flettner rotor is studied by both three-dimensional PIV measurements and RANS simulation for a case with Re equal to 2.0 104, based on the inlet velocity (U) and cylinder diameter (D) for the aspect ratio 6, and spin ratio equal to 4.3.
A test model of Flettner rotor is installed in the wind tunnel. A thin polymethyl methacrylate disk with diameter of 2D is installed at the top the cylinder following Prandtl1. The horizontal measurement plane is perpendicular to the axis of cylinder as shown in figure 1. To build up the fully three dimensional measurement data, 62 sequences of two-dimensional three components measurements at different axial position are made.
The steady RANS simulation is done with SST k –ω model. The geometry of Fletter rotor as in wind tunnel measurement is used. The size of computation domain is chosen according to the one in the literature2. The domain is discretized by a hexahedral mesh, with the carefully designed boundary layer mesh around the rotor (see Figure 1). A uniform velocity inlet boundary condition is used for the inlet and slip boundary condition is chosen for the sides.
Both PIV measurement and CFD show similar vortices around the rotor but with some differences as indicated in Figure 2: the simulation cannot well predict the flow at the middle plane, which important for the lift prediction. Further verification and validation will be done with force measurement.