A mixing-length method for predicting heat transfer in rough pipes

摘要: Abstract A mixing length formulation which includes a finite value at hypothetical surface within the roughness is used to predict heat transfer in rough pipes. Several empirical parameters are required this and these were obtained by making comparisons of predictions, using range parameterzs, with experiments. The experiments carried out airflow pipes roughened internally screw threads Reynolds number 2 × 10 4 3 5 . Simple correlations suggested for variation two most important namely cavity Stanton number. Using enables appropriate form energy equation one-dimensional flow be solved numerically thermal entrance region any boundary condition Prandtl numbers other than unity. Good agreement shown measurements uniform wall flux.