In this paper, the hydrodynamic performance of Magnus effect swing rotating cylinder is studied by model experiment and PIV experiment, the influence of swing speed, swing angle and swing-to-rotate ratio of swing rotating cylinder on lift and flow field structure is analyzed. It is found that the lifting force of the cylinder increases with the increase of the swing-to-rotate ratio and tends to be stable after reaching the maximum value; The lift of the cylinder increases all the time with the increase of the swing speed, the stable section moves backward gradually; The lift of the cylinder increases gradually with the increase of the swing angle. With the increase of swing-to-rotate ratio, the distance of the lag and forward movement of the separation point on the upper and lower surfaces of the cylinder, the angle between the vortex shedding and the horizontal direction increases. The increase of swing velocity can intensify the fusion and breaking of positive and negative vortices, and make the wake field more disordered.
When the viscous fluid passes through the rotating cylinder, the relative velocity difference between the upper and lower sides of the cylinder will be generated due to the rotation of the cylinder. According to Bernoulli equation, the pressure difference between the upper and lower sides of the rotating cylinder will be generated, resulting in a force perpendicular to the flow direction. However, there are many cases of no flow in engineering that need Magnus force, such as the ship's zero speed anti rolling. At this time, Magnus force cannot be generated only by the rotation of the cylinder, and the cylinder needs to be swung to obtain the relative flow speed.At present, the researchers have not carried out relevant research on the swinging rotating cylinder. The main research focuses on the rotating cylinder. The first experiment of the rotating cylinder is Prandtl (1925). He found that there is a limit lift value of 4π in the laminar flow of the rotating cylinder. Due to the limitations of technology, it is impossible to measure and study the vortex shedding of a rotating cylinder. Kang (1999) studied the flow around a rotating cylinder under laminar flow. He found that a rotating cylinder based on viscous flow can improve the wake at certain speed ratios, suppress vortex shedding, and effectively reduce flow-induced vibration. Ingham (2014) studied the flow of rotating cylinders at low Reynolds numbers through numerical simulation. Chen (1993) studied the rotating cylinder at Re=200 through numerical simulation and found the vortex release process of multiple vortices in the wake at higher speeds. Kang (2006) found that the flow field will be relatively stable at certain relative speeds when the Reynolds number is small in subsequent studies. Mittal (2003) studied the time-domain variation of the lift resistance coefficient of a rotating cylinder at a Reynolds number of 200-1000. Dmitry A (2012) based on OpenFOAM used large eddy simulation to study the flow of a rotating cylinder with a Reynolds number of 3900. Karabelas (2012) used the LES method to calculate the flow around a rotating cylinder at a Reynolds number of 140,000. He found that as the speed ratio increased, the resistance of the cylinder decreased and the lift increased. In recent years, with the rapid development of computer technology, the speed of image processing has been rapidly improved. Many researchers have proposed new experiment methods for flow field measurement. Among them, the most widely used is particle image velocimetry..Lam (2002) studied the sinusoidal oscillatory motion of cylindrical turbulence through the PIV experiment. He analyzed the distribution and development of large-scale vortices in the flow. K.M. Lam (2009) subsequently analyzed the distribution and development of the vorticity field of the cylinder with low rotation speed in the range of 3600~5000 Reynolds number through the PIV experiment. Zhanqi Tang (2018) measured the cylindrical turbulent boundary layer by particle image velocimetry.Kumar studied the coupling characteristics of two parallel cylinders with the same rotation speed through hydrogen bubble flow display technology and particle image velocimetry. The maturity of PIV technology has further developed the research of rotating cylindrical flow field.
