Publisher Summary Accurate knowledge of the overall convective heat transfer from circular cylinders is of importance in a number of fields, such as boiler design, hotwire anemometry, and the rating of electrical conductors. The wide dispersion in the published experimental data for the heat transfer from smooth circular cylinders by natural and forced convection is attributed to various factors associated with the experiments. The error due to heat conduction to the supports is particularly important with natural convection, especially where the heat loss and the temperature rise of the cylinder are calculated from the voltage drop across it. A common cause of error is the use of too small a space ratio, so that the temperature and velocity fields are distorted. To reduce this error to less than l%, the space ratio D c /D for natural convection or D T /D for forced convection should exceed 100. The error caused by blockage with wind tunnel measurements can be calculated depending on the type of tunnel. One of the greatest sources of error with forced convection is the failure to allow for the effect of stream turbulence.

The Overall Convective Heat Transfer from Smooth Circular Cylinders

Heat transfer surface enhancement through the use of longitudinal vortices: a review of recent progress

Longitudinal vortices are more efficient for heat transfer enhancement than transverse vortices.A survey is given on triangular and rectangular protrusions from a heat transfer surface which generate mainly longitudinal vortex systems. Wings and winglets are considered in boundary layer and channel flow, either by themselves, or in a single row transverse to the flow direction, or in a two dimensional array. Local and global heat transfer are studied as a function of the major parameters. For channel flows also the pressure losses are given. Winglets are superior to wings, but winglet form is of minor importance. In laminar flow, heat transfer enhancement increases with Reynolds number. Heat transfer enhancement increases for constant winglet aspect ratio with angle of attack up to a maximum angle of attack. But it increases also up to limiting values with winglet height relative to transverse and streamwise winglet spacing and relative to channel height or boundary layer thickness. The nonlinear character of fluid mechanics does not allow simple predictions.

Vortices, Generators and Heat Transfer

Thermal management and temperature uniformity enhancement of electronic devices by micro heat sinks: A review

Numerical study on laminar convection heat transfer in a rectangular channel with longitudinal vortex generator. Part A: Verification of field synergy principle

T. R. Johnson

Papers

The Influence of Vortex Generators on the Drag and Heat Transfer From a Circular Cylinder Normal to an Airstream