Question

The buzzing instability in the supersonic inlets usually occurs at

• A. Subcritical operation
• B. Critical operation
• C. Supercritical operation
• D. Both critical and supercritical operation

Hint:

Buzz is an unsteady phenomenon leading to loss in engine performance.

Answer 1

The Correct Option is A

The buzzing instability in supersonic inlets typically occurs during subcritical operation. Supersonic inlets are designed to handle airflow efficiently at speeds greater than sound. The operation conditions can be broadly categorized as subcritical, critical, and supercritical, each having unique characteristics regarding the behavior of the shock waves within the inlet.

Subcritical Operation: During subcritical operation, the mass flow rate of the inlet is less than the designed value, causing the normal shock wave to stand inside the duct. This leads to flow instabilities and vibrations known as "buzzing." This condition results in inefficient inlet performance and is undesirable in aerospace applications.

Therefore, the buzzing instability is specifically associated with subcritical operation due to the improper position and stability of the shock wave within the supersonic inlet.