There are some very interesting practical articles on this website:
http://autospeed.drive.com.au/cms/A_1023/article.html
Unfortunately you have to pay for them and they don’t go into much theory. Some nice pictures though and some really useful practical advice on using manometers and magnehelic gauges to study aerodynamics. The short free introductions to the articles are often enough to get a picture of what they are suggesting.
Craig