Experimental study of combined convective heat transfer from horizontal cylinders in an axial flow

Combined free and forced convective heat transfer from horizontal cylinders arranged with their axes parallel to a forced air flow has been measured. Five models were used in the present study, these models being made from solid aluminum. The heat transfer rate was determined by the transient method, i.e., by heating the model and then measuring the rate at which it cooled when placed in the air stream. Tests were carried out in this way with each of the five models at air velocities of from 0 to about 1.3 m/s. The results of the tests have been correlated using a form indicated by the boundary-layer equations. From this correlation the conditions under which this flow can be assumed to be purely forced convective or purely free convective have been deduced.