Effects of boundary-layer bleed parameters on supersonic intake buzz

Aerodynamic Instabilities in High-Speed Air Intakes and Their Role in Propulsion System Integration

“…With an increase in the freestream Mach number, the normal shock is strengthened, which promotes flow separation over the spike. Thus, the stability margin is affected since the intake buzz phenomenon is initiated earlier at higher mass flow rates and, therefore, at different operating conditions [36,37,62,90,91]. This is clearly depicted in Figure 7.…”

“…It is evident that a slot boundary layer bleed can significantly improve the intake performance and stability by preventing flow separation on the compression surface [58,91,108], especially when the shock train is close to the slot region [61,109]. Sethuraman et al [109] managed to reduce the shock oscillation by 50% with suction control, and reduced the oscillating frequency of the first shock by about 5 Hz, illustrating the effectiveness of the suction control when the shock train appears closer to the slot region [110].…”

“…To this end, numerous techniques were developed to control flow separation, such as the passive or active boundary layer bleed, vortex generators, mass injection, and energy deposition. A comprehensive review article published by Younsi et al [107] in 2018 summarizes the development of boundary layer suction in high-speed air intakes and the effects of various bleed parameters on intake performance and stability. To avoid repetition, studies focusing on the suppression of buzz through the use of boundary layer bleed will be reviewed, considering publications from 2018 onward.…”

“…There are two types of bleed systems used: porous and slot. Generally, the slotted bleed is used when the region of separation is known, and a large mass is required to be bled out, while the porous bleed is used when the boundary layer separation can vary with time, or the exact region of separation is unknown, and a small uniform air mass is required to be bled out [107].…”

“…Soltani et al [61,90,117] investigated the effect of the slot bleed and its parameters on the intake performance across design and off-design conditions. Younsi [107] experimentally investigated the effects of several bleed parameters, such as slant angle, entrance area, and bleed position for both porous and slotted bleed systems. Moving the bleed system forward at the tip of the cone is ineffective at improving the intake stability margin, since the flow separation that triggers the shock oscillations is further downstream.…”