SIMULATION OF NATURAL PERTURBATIONS OF THE BOUNDARY LAYER AND CONTROL OF THEM WITH USE OF DISTRIBUTED SUCTION
In this work, modeling of natural disturbances in the boundary layer of a flat plate is carried out and the influence of distributed suction through a hydrodynamically smooth surface on natural and acoustic-generated disturbances of the sliding wing boundary layer is studied. It was shown that the impulse action of the membrane generates a perturbation in the Blasius boundary layer, consisting of a longitudinal structure and Tollmien-Schlichting wave packets at the perturbation fronts. An analysis of the evolution of this perturbation showed that the amplitude of the longitudinal structure decays downstream. Wave packets behave according to the linear theory of hydrodynamic stability: under certain conditions they grow and lead to a laminar-turbulent transition. The influence of suction on natural perturbations of the boundary layer, which develop under natural conditions, was studied. In addition, disturbances were amplified by means of acoustic impact at the carrier frequency of natural disturbances. Without the use of suction, natural disturbances actively grow under these conditions, up to the formation of turbulent patches at the end of the measurement region. The separation contributes to the rapid growth of the perturbation amplitude and the early transition. The effect of suction eliminates the separation, and damping of perturbations is observed. The measurements of the level of integral pulsations at the end of the measurement area differ by a factor of 10. Acoustic influence increases the rate of amplitude increase. Distributed suction also affects acoustically amplified natural perturbations, eliminating their growth throughout the entire measurement area.