If the airflow atop the airfoil increases, static pressure will _________ and dynamic pressure will _____________.

If the airflow atop the airfoil increases, static pressure will _________ and dynamic pressure will _____________.

• A. increase, decrease
• B. increase, increase
• C. decrease, decrease
• D. decrease, increase

Answer: (D)

Bernoulli’s principle ties flow speed to pressure on a surface. When the air moves faster over the top surface of an airfoil, the static pressure on that surface falls to keep the total (static plus dynamic) pressure along a streamline consistent. At the same time, dynamic pressure, which is ½ρV², increases because velocity is higher. So increasing airflow atop the airfoil leads to a decrease in static pressure and an increase in dynamic pressure, contributing to the lift generated by the pressure difference between the top and bottom surfaces.

Bernoulli’s principle ties flow speed to pressure on a surface. When the air moves faster over the top surface of an airfoil, the static pressure on that surface falls to keep the total (static plus dynamic) pressure along a streamline consistent. At the same time, dynamic pressure, which is ½ρV², increases because velocity is higher. So increasing airflow atop the airfoil leads to a decrease in static pressure and an increase in dynamic pressure, contributing to the lift generated by the pressure difference between the top and bottom surfaces.