Interactional aerodynamics has been studied for counter-rotating coaxial rotors in hover. The effects of torque balancing on the performance of coaxial-rotor systems have been investigated. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model. Computational results for an experimen...

This paper reports the result of an analytical investigation of a steady, incompressible and viscous flow between two eccentric, rotating cylinders at high Reynolds number. A one dimensional case is far from reality because the gap between the cylinders is very small. Further, when their axes are displaced by a small distance, usually caused by bearing loads, two dimensional effects become obvi...

The stability of viscous flow between rotating cylinders in the presence of a constant axial magnetic field is considered. The boundary conditions for general conductivities are examined. It is proved that the Principle of Exchange of Stabilities holds at zero magnetic Prandtl number, for all Chandrasekhar numbers, when the cylinders rotate in the same direction, the circulation decreases outwa...

Experimental data are presented for large arrays of rotating, finite-height cylinders to study the dependence of the three-dimensional (3D) mean flows on the geometric and rotational configurations of the array. Two geometric configurations, each with two rotational configurations, were examined at a nominal Reynolds number of 600 and nominal tip-speed ratios of 0, 2, and 4. It was found that t...

The Direct Simulation Monte-Carlo technique (DSMC) is used for numerical analysis of rarefied-gas hypersonic flows near a blunt plate, wedge, two side-by-side plates and cylinders, sphere, torus, and rotating cylinder. Important kinetic effects that are specific for the transition flow regime have been found: nonmonotonic lift of plates, strong repulsive force between side-by-side plates and cy...