Good point about the law of unintended consequences and wind tunnels. I once did some work in the 11.5 x 8.5 on a novel ram air inflated retarder I'd designed. I was trying to visualise the complex flow around the thing when inflated, which needed the tunnel to operate at the nominal store terminal velocity of around 30 m/S (about 70mph).
To do this, I stood inside the working section, wearing a retaining strap fixed to the upstream side of the balance arm on which the model and test item was mounted. Flow visualisation was by oil spray via a wand, which worked very well indeed. The problem is that one can get carried away with curiosity, so I spent much longer than planned exploring the complex flow around the thing, as it was absolutely fascinating seeing how well theory tied up with reality.
It wasn't until we shut down and I walked back into the control room that I realised one inherent disadvantage with a closed loop tunnel - you tend to get your own back, so to speak. I'd foolishly gone into the tunnel wearing normal work clothes, that were now thoroughly soaked in the vegetable oil used to create the wand mist..........................
Oh happy days!