Core-pressure alleviation for a wall-normal vortex by active flow control

TL;DR

This paper explores active flow control methods to modify the pressure distribution in wall-normal vortices, aiming to weaken vortex strength and prevent hollow-core vortex formation in turbomachinery applications.

Contribution

It introduces a novel active flow control technique using rotating zero-net-mass blowing and suction to alter vortex core pressure distribution.

Findings

Control widens vortex core and increases pressure

Flow control weakens vortex strength

Potential to inhibit hollow-core vortex formation

Abstract

We consider the application of active flow control to modify the radial pressure distribution of a single-phase wall-normal vortex. The present flow is based on the Burgers vortex model but with a no-slip boundary condition prescribed along its symmetry plane. The wall-normal vortex serves as a model for vortices that emerge upstream of turbomachinaries, such as pumps. This study characterizes the baseline vortex unsteadiness through numerical simulation and dynamic mode decomposition. The insights gained from the baseline flow are used to develop an active flow control technique with rotating zero-net-mass blowing and suction for the objective of modifying the core pressure distribution. The effectiveness of the control strategy is demonstrated by achieving a widened vortex core with increased pressure. Such change in the flow field weakens the local strength of the wall-normal vortex core, potentially inhibiting the formation of hollow-core vortices, commonly encountered in liquids.