How to dry out the inside of a bicycle frame? I have a bicycle with a high carbon steel frame. For the most part, this frame is sealed off from the air, but there are some bolts, through which water can get through during rainy days or when washing the bicycle. I am concerned this could cause rust.

Is there a method by which to dry the interior of the bicycle out, to avoid rust?
The most important thing to do to keep the inside dry and prevent excess rust is a proper drain hole on  the underside of the bottom bracket. Outside of issues with heavily salted roads, drain holes are enough to prevent meaningful rust. The next step is something like Weigle framesaver, or just a blast of aerosol lube every couple years in each tube. Framesaver is great against salted roads, but otherwise is usually overkill.