Influence of Sound upon Separated Flow over Wings

Effect of Acoustic Excitation Amplitude on Airfoil Boundary Layer and Wake Development

“…2b), boundary layer behaviour and wake development change dramatically. A separation bubble forms on the upper surface of the airfoil, resulting in a narrower wake for this Reynolds number compared to that for Re c =100x10 3 . In addition, vortical structures that form in the wake region are associated with smaller length scales and are less coherent than those observed for the lower Reynolds number.…”

“…The airfoil was studied for a range of chord Reynolds numbers (Re c ) and several angles of attack (). To illustrate boundary layer and wake development in the unexcited flow, flow visualization results for Re c =100x10 3 and Re c =150x10 3 at =5 are shown in Fig. 2.…”

“…Several studies have demonstrated that introduction of either external or internal periodic excitation, e.g., acoustic waves, at an appropriate frequency and amplitude can improve airfoil performance that is adversely affected by laminar separation. [2][3][4][5][6][7][8][9][10][11][12] In the case of external excitation [3][4][5][6][7][8][9][10] , acoustic waves are generated by a remote source; whereas, for internal excitation [9][10][11][12] , periodic disturbances are introduced directly into the boundary layer, e.g., from a slot in the airfoil surface. For both types of excitation, it has been shown that the effect depends strongly on the excitation frequency and amplitude.…”

“…However, efficiency of the flow control with internal excitation depends strongly on the location and the orientation of the slot, with the optimum configuration of these two parameters remaining uncertain. 3 Despite significant insight produced by several studies into the active flow control of laminar boundary layer separation, the attendant flow control mechanism is not fully understood. In particular, the effect of excitation amplitude on flow transition and wake characteristics has not been investigated in detail.…”

Using synthetic jet generators in the systems of control of separated flows of turbomachines

“…Найменш дослідженим, але найбільш перспективним методом активного керування потоком -є метод ім-пульсної інжекції або вдув робочого тіла [8][9][10][11]. Раніше даний метод не вивчався через його дороговизну та великі енергетичні затрати, але представляє значний науковий інтерес, що обумовлений його перспекти-вою на даний час.…”