In this fuel system, how is motive flow generated for ejector operation?

In this fuel system, how is motive flow generated for ejector operation?

• A. By the high-pressure output of engine-driven pumps
• B. By battery power
• C. By cabin air pressure
• D. By gravity feed from the wing tanks

Answer: (A)

The key idea is how motive flow for an ejector is created. An ejector uses a high-energy motive fluid to pull in additional fuel and move it through the system. In most fuel systems, the energy needed to generate that motive flow comes from the high-pressure output of engine-driven pumps. The high-pressure fuel is directed through the ejector nozzle, creating a fast jet that entrains fuel from other parts of the system and drives the transfer. Other sources wouldn’t reliably provide the required energy: battery-powered (electric) pumps exist in some layouts but aren’t the typical motive flow source for ejectors; cabin air pressure is unrelated to fuel transfer; gravity feed lacks the pressure and consistency needed to drive ejector operation, especially at altitude.

The key idea is how motive flow for an ejector is created. An ejector uses a high-energy motive fluid to pull in additional fuel and move it through the system. In most fuel systems, the energy needed to generate that motive flow comes from the high-pressure output of engine-driven pumps. The high-pressure fuel is directed through the ejector nozzle, creating a fast jet that entrains fuel from other parts of the system and drives the transfer.

Other sources wouldn’t reliably provide the required energy: battery-powered (electric) pumps exist in some layouts but aren’t the typical motive flow source for ejectors; cabin air pressure is unrelated to fuel transfer; gravity feed lacks the pressure and consistency needed to drive ejector operation, especially at altitude.