HEAT TRANSFER IN HELICAL CHANNELS WITH STRONG CURVATURE
We present experimental results on the heat transfer from the convex and the concave walls of coil-shaped channels for a wide range of the curvature factor D/h from 5.5 to 84.2. Velocity profiles and Reynolds stresses were also measured in a channel of D/h = 6.7. Laminar-turbulent transitions on strongly curved convex and concave walls were observed at significantly different values of Re. Prediction relations were found for the critical Reynolds number and for the heat transfer rates from the concave and the convex walls in the turbulent, laminar-vortical and critical flow modes.