CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   calculating missle configuration by panel method (http://www.cfd-online.com/Forums/main/5594-calculating-missle-configuration-panel-method.html)

 Daniel December 30, 2002 09:28

calculating missle configuration by panel method

Hello

I'm having some difficulties getting acceptable result using a panel program on some wing-missle configuration. I know that the VLM method is based upon vortex, and missle configuration usualy have some small lifting surface with low AR

is this is the resone for the bad results? Has anyone got some exeptable result with a panel method upon a missle configuration?

Thanks, Daniel

 Peter Attar December 30, 2002 20:53

Re: calculating missle configuration by panel meth

The vortex lattice model assumes a thin surface..thickness effects are neglected..ie no source elements are used. This may be fine for the lifting surface but to model the actual missile you will probably need to use an actual panel method which includes sources and doublets(or vortices).

 Daniel December 31, 2002 11:01

Re: calculating missle configuration by panel meth

What a about a program like cmarc ((by aerologic) which has a wake definition method for the lifting surfaces?

is Anyone familiar with this panel program and had some successful results on wing-missle configuration?

 Peter Attar December 31, 2002 11:10

Re: calculating missle configuration by panel meth

I've never used it but just looking at the webpage it looks like it is a panel method...which usually by definition means that it solves for both doublet and source distributions. If you have the software have you even attempted to look at the theory manual? In your original post you said a panel method but then went on to describe a vortex lattice method which are two slightly different methods(the VLM being a subset of the more complete panel code) If you are specific problems matching results explain them further and perhaps somebody will able to help you out.

 Charles Crosby January 6, 2003 06:17

Re: calculating missle configuration by panel meth

A vortex lattice or panel method is unlikely to give good answers for a missile wing/body combo. Unless you are operating at a smallish angle of incidence non-linear effects are far too significant to ignore. For a missile vortex lift (off a swept wing leading edge) and body lift (affected by the exact position of the separation line along the body) are very important.

 Peter Attar January 6, 2003 09:09

Re: calculating missle configuration by panel meth

Very true...however for some models a good approximation can be made for vortex lift by treating the leading edge as a separation line and releasing panels from it just like is done with the trailing edge. Good correlation is seen for these types of models up to the point where vortex breakdown occurs. I've done this myself with my own code and for steady flows for a 76 degree delta wing the results are pretty good.

I'm not sure if the code that the OP is using allows the user to define separation lines but if so he may want to look into it.

 All times are GMT -4. The time now is 19:47.