Research in Engineering and Aviation

A Computational and Experimental Investigation of Flow over an Inflatable Wing

June 2012

Author(s): Ghobadi, K.J., E. Pifer, R.P. LeBeau, G. Bramesfeld, and M. McQuilling

A Computational and Experimental Investigation of Flow over an Inflatable Wing. 30th AIAA Applied Aerodynamics Conference, AIAAA-2012-2899, New Orleans, LA, June 26.


 Inflatable wings provide a compact alternative for aircraft that need to fit into small volumes before deployment, such as backpack unmanned aircraft or rocket-delivered air vehicles. The naturally undulating airfoil surface created by the inflation chambers may also provide an opportunity for flow control, as early wind tunnel tests indicated that separation over these airfoils was reduced compared to their smooth counterparts. Subsequent efforts to replicate these advantages computationally have proven ambiguous—while under certain conditions the inflatable airfoil may improve the lift-to-drag characteristics of the wing, in other conditions the inflatable profile appears detrimental. Further, these results have not been satisfactorily compared to experiments to confirm their validity. To attempt to address this, a series of PIV measurements has been taken for both a bumpy and smooth NACA 4318 airfoil at varying Reynolds number and angle of attack. This data is compared to CFD simulations in order to validate the models and gain further insight in to the flow physics. The combined computational/experimental analysis will allow for a better determination of the performance penalty or benefit that occurs due to the bumpy surface. Select three-dimensional simulations will also be used to further illuminate the effects of the bumpy surface on the aerodynamics.