Investigation of the prolate ellipsoidal particle motion in a swirling flow

In this paper, the investigations of the prolate ellipsoidal particles movement in a swirling flow were carried out. The motion of small particles relative to the carrier fluid flow is insignificant. As a result, the smallest particles move along a helical path at an approximately cylindrical surface. Large particles affected by centrifugal force move to the walls of the outer cylinder along a conical surface. Increasing of the angular velocity of the cylinders leads to an increase in the centrifugal force which intensifies the radial motion of the particles to the outer cylinder. It is found that, depending on the particle orientation in the space, both upward and downward motions are possible. The movement is caused by particular drag force influence on the ellipsoidal particle. The drag force is characterized by the horizontal and vertical components. The horizontal component for heavy particles with density value greater than that of the carrier medium is directed towards the axis of symmetry. The direction of the vertical component of the drag force depends on the orientation of the particles in the space. Utilizing the particle slip velocity model, the regimes of upward and downward movement are defined. Dependencies for the determination of particle velocity components are proposed. It is found that the gravitational settling velocity of the particle decreases with an increase in the value of the Froude number. In the case of a strong swirling flow, the motion of the particle becomes upward.

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