As air moves from a larger area to a smaller area, it contracts as it passes through the opening. This happens when moving from a large duct into a smaller duct, or from the ambient air into a hood opening.

As air moves from a larger area to a smaller area, it contracts as it passes through the opening. This happens when moving from a large duct into a smaller duct, or from the ambient air into a hood opening.

• A. Inlet
• B. Duct
• C. Air Cleaner
• D. Contractions

Answer: (D)

Air moving into a smaller opening speeds up as it passes through the narrowing. This reduction in cross-sectional area causes the flow to contract, which is why you see this when air goes from a large duct into a smaller duct or from ambient air into a hood opening. The term for this behavior is contraction, reflecting the streamlining of the flow as it moves through the constricted path. Inlet would describe the entry point itself, duct is the passage the air travels through, and an air cleaner is a device that removes particles. So the described phenomenon is best described as a contraction.

Air moving into a smaller opening speeds up as it passes through the narrowing. This reduction in cross-sectional area causes the flow to contract, which is why you see this when air goes from a large duct into a smaller duct or from ambient air into a hood opening. The term for this behavior is contraction, reflecting the streamlining of the flow as it moves through the constricted path. Inlet would describe the entry point itself, duct is the passage the air travels through, and an air cleaner is a device that removes particles. So the described phenomenon is best described as a contraction.