What type of design do motive flow fuel pumps use?

Motive flow fuel pumps typically utilize a positive displacement design for their operation. This design is characterized by its ability to move a specific volume of fuel with each cycle, ensuring a consistent flow and pressure necessary for the proper functioning of aircraft engines. Positive displacement pumps are crucial in aviation because they maintain a steady supply of fuel regardless of changes in pressure within the fuel system.

In contrast, centrifugal designs rely on rotational energy to move fuel, which can be less efficient at low flow rates. Venturi designs function based on the principle of fluid dynamics and create a pressure differential to draw fuel through, making them unsuitable for consistent positive flow under various operational conditions. Diaphragm pumps, while used in some applications, do not provide the same direct and reliable fuel supply as positive displacement pumps in aviation applications. Understanding the mechanics and characteristics of these different pump types is essential for recognizing their appropriate applications in aircraft fuel systems.