Tennessee Wastewater Operator Practice Exam

What is created by the rotational velocity of the shaft within the air foil bearings?

1. Mechanical pressure

2. Hydraulic pressure

3. Air cushion

4. Vapor retention

The correct answer is: Air cushion

The correct answer is that the rotational velocity of the shaft within the air foil bearings creates an air cushion. This phenomenon is essential for the function of air foil bearings, which rely on the generation of a thin film of pressurized air to support the rotating shaft. As the shaft rotates, the special design and surface characteristics of the air foil bearings allow air to be drawn into the bearing clearance, leading to the formation of an air cushion around the shaft. This air cushion reduces friction significantly compared to traditional bearings by keeping the rotating shaft separated from the bearing surface. The effectiveness of this air cushion is directly influenced by the speed of rotation; higher speeds lead to a greater generation of the pressurized air, enhancing the support and stability of the shaft. Other options might relate to concepts in fluid dynamics or bearing technology, but they do not specifically describe the phenomenon occurring in air foil bearings as accurately as the air cushion, which is the primary mechanism ensuring low friction and effective operation in high-speed applications.