This study investigates the active control of the precessing vortex core, a detrimental global instability in strongly swirling flows. Experiments were conducted on a canonical aerodynamic model, employing time-resolved particle image velocimetry, laser Doppler anemometry, and acoustic measurements to characterize the flow response. Ten distinct actuators, varying in orientation (axial, radial, and combined) and geometry, were used to inject control momentum, with the effort quantified by the dimensionless momentum flux coefficient Cμ. The results demonstrate that Cμ provides a linear scaling for the change of the integral swirl number. The change in the global flow field is analyzed using the strain-rate tensor and the spatial distribution of tangential velocity pulsations. Targeted radial injection most effectively reduces angular momentum near the axis and interrupts the energy supply to the instability. A quadratic relationship is established, showing that the wall-pressure pulsations scale with the square of the amplitude tangential velocity fluctuations. The results provide physics-based guidelines for designing efficient, low-energy flow control systems to mitigate vortex-induced instabilities.
Suslov et al. (Wed,) studied this question.