Lately I did add a coupling between MIAReX and Xfoil : MIAReX can handle Xfoil calculation. You can automatically generate polars file needed for non linear lifting line calculation.
You can also compute and then display at screen the pressure locally along span.
once the lifting line calculation is converged, local condition are known (local alpha, local Reynolds) at any station along span . Miarex then compute the Cp distribution along chord at this station, and display it. You can then imagine pressure surface generated by the wing airflow.
|You can also fill the wing surface with colors corresponding to local CP value.|
Here is a page about a program I wanted to have since a while : a program that compute polar for multi-airfoil wing.
The calculation method used is based on lifting line theory, généralised to non linear behaviour of airfoil section. It computes lift distribution along span, with induced angle for finite wing. Then the program do the sum of local lift Cl, induced and airfoil drag Cdi& Cdairf, and airfoil moment Cm, to get global coefficient Cl, CDI, CDairf, andCM.
This program is based on formula developed by James C. Sivells & Robert H. Neely
in NACA TN-1269 (1947) :
For a rectangular wing, the chord is constant
along span, hence Reynolds number. We may thinks that taking raw 2D data
for airfoil behaviour is a fairly good approximation.
This is not as a good approximation, since allong span the induced angle changes, and then the airfoil local drag. Thanks MIAReX we will evaluate the effect of this 3D phenomenon on the overall performance.
|We draw here 2d data for NACA 2412 airfoil and the result given by MIAReX for the airfoil only on a rectangular wing (AR=15). We can see that the behaviour of the equivalent airfoil on a finite wing is not the same as the 2D airfoil. The effect is even bigger on smaller AR.|
For the same rectangular wing (AR=15), we evaluate polar with 2D raw data and simplified formula.
Then we compare to MIAReX result, coupling both 2D result and finite wing aspect.
Once again, the result is not the same. The difference is even bigger for higher AR.
Here is the story of the "aerodynamic tuning" of a small Nimbus 4D model, that had strange behavior. MIAReX was used for wing pitching moment analysis.
MIAReX was used for illustrating www.cirrusstandard.org web site.
Matlab Optimisation toolbox is a very powerful set of numerical optimization routines. The output of Miarex calculation was redirected to those optimisation routines, for precise design cases.