What happens to airflow when the diameter of a duct increases?

When the diameter of a duct increases, the airflow typically increases. This occurs because a larger diameter allows for a greater volume of air to move through the duct at a given pressure. The relationship between duct diameter and airflow is directly linked to the principles of fluid dynamics: as the cross-sectional area of the duct increases, it can accommodate a greater mass flow rate of air while maintaining an equivalent pressure drop.

Additionally, increasing the diameter reduces the velocity of the air moving through the duct for the same volume flow rate, which can lead to smoother flow conditions and reduced friction losses. This effect can enhance the overall system performance by allowing for more efficient air movement.

Understanding this principle is crucial for properly designing ductwork in heating, ventilation, and air conditioning (HVAC) systems, as it helps ensure that sufficient airflow is maintained for effective climate control. When ducts are sized appropriately, the efficiency of the system improves, which can lead to lower energy consumption and better comfort levels.