Concave-wall Laminar Heat Transfer and Görtler Vortex Structure
Author | : |
Publisher | : |
Total Pages | : 0 |
Release | : 1990 |
ISBN-10 | : OCLC:1406983935 |
ISBN-13 | : |
Rating | : 4/5 (35 Downloads) |
Book excerpt: The mean velocity field in the boundary layer and the streamwise and spanwise distributions of heat transfer coefficient have been measured on a concave wall in the presence of naturally-generated Görtler vortices, with and without a preceding flat wall. In near-zero pressure gradient, enhancement of the streamwise-averaged heat transfer above flat surface levels was associated with the attainment of a Görtler number of around ten, as found in previous experiments in a different flow facility with higher wall curvature, but occurred before the onset of severe distortion in the velocity profiles. Velocity gradient parameters K of 0·20 × 10−6 and 0·75 × 10−6 resulted in a more regular vortex structure, with spanwise averaged heat transfer reaching two to three times predicted levels. At K = 1·8 × 10−6, vortex amplification was suppressed to such an extent that no significant heat transfer enhancement took place. Comparison of measured Stanton numbers with those derived from skin friction factors (obtained from velocity profiles) suggested that the heat transfer enhancement is not simply a result of fuller velocity profiles in vortex downwash regions.