Choked gas release occurs when the throat velocity reaches which speed?

Choked gas release occurs when the throat velocity reaches which speed?

• A. True
• B. False
• C. Depends on gas
• D. Cannot determine

Answer: (A)

Choked flow happens when the flow at the constriction reaches sonic speed. At the throat, once the local Mach number reaches 1, the gas is moving at the speed of sound, so v_throat equals a (the speed of sound). This sonic condition, v = a, sets the maximum velocity at the throat. From that point on, lowering downstream pressure cannot push more mass through the throat—the flow is then controlled by the throat area and upstream conditions. In practical terms, the throat velocity equals the local speed of sound, which is a = sqrt(gamma * R * T) for the gas.

Choked flow happens when the flow at the constriction reaches sonic speed. At the throat, once the local Mach number reaches 1, the gas is moving at the speed of sound, so v_throat equals a (the speed of sound). This sonic condition, v = a, sets the maximum velocity at the throat. From that point on, lowering downstream pressure cannot push more mass through the throat—the flow is then controlled by the throat area and upstream conditions. In practical terms, the throat velocity equals the local speed of sound, which is a = sqrt(gamma * R * T) for the gas.