XFOIL Tutorial Part 3
Wednesday, 02 December 2009 03:41 | 
Written by Aleksey Matyushev | 
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Analyzing the airfoil
To analyze the airfoil you must enter the operational mode of XFOIL. This operational mode can be entered by the following command from the main XFOIL menu:
XFOIL c>oper
After entering the operational mode of XFOIL, the flow conditions and angle of attack for analysis needs to be given. The angle of attack can be varied by using the following command:
.OPERi c>alfa #
Where '#' designates an integer. After giving this command, a graphcal window will appear depicting the pressure distribution across the airfoil. In the upper right hand corner there will be numbers depicting the current angle of attack, calculated coefficient of pressure, coefficient of moment, and coefficient of drag (parasite).
It should be noted that the the 'i' in ".OPERi c>" stands for inviscid flow, meaning neglecting frictional effects.
So to analyze a NACA 2432 airfoil at 4 degrees angle of attack in inviscid flow, the following commands should be given upon launching XFOIL:
XFOIL c> naca 2432
XFOIL c> oper
.OPERi c> alfa 4
After entering the commands above, the following plot should pop-up.
NACA 2432 IN INVISCID FLOW
To analyze the same airfoil in viscous flow (flow with friction) at a Reynolds number of 2e6 and the same angle of attack, the following commands need to be given (continuing from the previous steps):
.OPERi c> visc
Enter Reynolds number r> 2e6
.OPERv c> alfa 4
After entering those commands, the following plot should be displayed by XFOIL:
NACA 2432 IN VISCID FLOW
This part of the tutorial summarized how to analyze an airfoil in in-viscid and viscid conditions using XFOIL's operational menu.
In a quick side note, if the Xplot11 (the plot) window is closed by the user during the operation of XFOIL and the user attempts to give another command in the terminal window, XFOIL will throw an error and usually quit. To avoid losing work, DO NOT close the plotting window...
Last Updated (Friday, 12 February 2010 20:17)
