I think you can come up with a repeating flame pattern. Take a rectangle of fabric, then accordian-fold it in wide pleats. Draw a curve across the width of the fabric with a pencil, not too complicated but whatever flame-edge shape you like. Grab the fabric up in small folds as you work along this line, then tie; after soda-soaking, drop thickened red dye along the crunched-up line, yellow on the inside, and thickened dark dye on the outside. That should give you a repeating flame. To see what I mean about the folds along the pencil line, see the Wiki tutorial on
tie-dyeing a heart pattern.
With some trial and error you should be able to find an excellent way to get exactly the effects you're asking for. What you're asking for seems like a pretty reasonable thing. Be sure to use a good fiber reactive dye, such as Procion MX or Drimarene K. Buy your dyes from Kraftkolour, which is near Melbourne, or mail-order them from Batik Oetoro, in Sidney.
Paula