What is the function of a sonic venturi in a turbocharger system?

• A. To limit turbocharger airflow used for cabin pressurization
• B. To increase turbocharger efficiency by cooling
• C. To cool the cabin air directly
• D. To regulate fuel flow

Answer: (A)

The function being tested is how a sonic venturi meters bleed air from the turbocharger to the cabin pressurization system. By creating a choking throat, it fixes the amount of air that can be drawn off for cabin pressurization across a range of turbine speeds and pressures. This keeps cabin pressure stable as engine speed and turbo output vary, effectively limiting how much airflow the compressor delivers to the pressurization system. It’s not about cooling cabin air, enhancing turbo efficiency through cooling, or regulating fuel flow, which is why the other options don’t fit.