Answer and Explanation:
To calculate the percentage of drag from pressure drag due to flow separation (form drag) for an NACA 2412 airfoil at zero degrees angle of attack and a Reynolds number of 8.5 x 10^6, we need to consider the following steps:
1. Determine the total drag coefficient of the airfoil, Cd.
2. Separate the drag into two components: pressure drag and skin-friction drag.
3. Calculate the percentage of drag from pressure drag (form drag) by dividing the pressure drag by the total drag and multiplying by 100.
Step 1: Determine the total drag coefficient, Cd.
The total drag coefficient can be obtained from experimental data or computational simulations for the specific airfoil at the given conditions. Without this information, it is not possible to accurately determine the total drag coefficient.
Step 2: Separate the drag into pressure drag and skin-friction drag.
In general, pressure drag is associated with the separation of flow around the airfoil, while skin-friction drag is due to the friction between the air and the surface of the airfoil.
Step 3: Calculate the percentage of drag from pressure drag.
Once we have the total drag coefficient, we can calculate the percentage of drag from pressure drag by dividing the pressure drag by the total drag and multiplying by 100. However, since we don't have the total drag coefficient or the specific values for pressure and skin-friction drag, we cannot provide an accurate percentage in this case.
To accurately determine the percentage of drag from pressure drag, it is necessary to have specific data about the airfoil, such as lift and drag coefficients, or information about the flow separation characteristics. Without this data, we cannot provide a precise answer to this question.