Question

Discuss how turbulence influence the heat transfer process in convection pipe flow

Answer 1

Reynolds number is the criteria to tell whether a fluid flow is laminar or turbulent. For incomprehensible flow through pipes or ducts,

If Re <2000 flow is laminar.velocity distribution is axi symmetric parabola.one later slides over the other without any intermixing bof fluid particles among fluid layers.

Re> 4000 flow is turbulent.velocity distribution is logarithmic.continuous intermixing of fluid particles among fluid layers with chunks of fluid mass jumping from one later to another carrying more mass,energy,momentum with them.

The flow of any gas in any pipe or ducts even at low velocities is generally turbulent.more often we come across turbulent flows rather than laminar during heat transfer in flow through pipes.

forany given fluid for a given pipe diameter and for given hotter conditions of pipe the h(convective heat transfer coefficient) values in turbulent flows are always greater than those of laminar flows and as the Reynolds number of flow increases in turbulent flow by increasing velocity h value increases.