Science Buddies: "Ask an Expert"

Hello,

I am currently trying to design a subsonic wind tunnel for a Fanwing test section.

However, the design of the test section and its associated force measurement apparatus necessitate an 'open-throat' wind tunnel.

I was wondering what the drawbacks where for open-throat wind tunnel design and some specifics I need to consider for its design, such as how large the tunnel cross section needs to be relative to the size of the projection of the Fanwing onto the tunnel cross section.

Right now I am thinking of using a 'simple cube pressure chamber' (https://www.sciencebuddies.org/science- ... fdb#p21456; Second post), with rectangular-cross-section tunnels. How would I design the aforementioned pressure chamber (I know the basic idea, but in the link guide vanes were mentioned), and how would I choose the fan for the posterior tunnel (behind test section)?

Thank you for your attention.

Hi,

I am sorry you had to wait so long for a reply. Here is a report of a National Committee that studied Open throat wind tunnels. I hope it helps:

http://naca.central.cranfield.ac.uk/rep ... rt-322.pdf

This is a multiage history of open throat wind tunnels, navigable from buttons on the bottom of the page:

http://www.hq.nasa.gov/pao/History/SP-445/ch3-2.htm

Another design report:

http://naca.central.cranfield.ac.uk/rep ... rt-412.pdf

I hope this helps answer your questions!

Good luck on the project!

Barrett L. Tomlinson

Fan Wings don't lend themselves to study in typical wind tunnels. Most tests on fan wing designs can be done in still air as they don't require forward speed to generate lift. Lift, drag, pitch, and various control tests don't require a wind tunnel. The tests that a wind tunnel offer to a fan wing design is cross wind and stall behaviors when the fan can't overcome the baseline wind.