Infrared thermography as a tool for thermal surface flow visualization

Abstract

Infrared (IR) thermography is a two-dimensional, non-contact technique of temperature measurement which can be usefully exploited in a vast variety of heat transfer industrial applications as well as research fields. The present work focuses attention on thermal surface flow visualizations of several types of fluid flow studied by means of the IR imaging system and in particular: the flow over a delta wing at angle of attack; the flow generated by a disk rotating in still air; air jets impinging on a flat wall; the flow inside a 180deg turn in a static channel with, or without, turbulence promoters; the flow inside a 180deg turn in a rotating square channel. Each flow visualization is illustrated through thermographic images and/or Nusselt number maps. The emphasis is on the capability of the infrared system to study: laminar-to-turbulent transition and location of primary and secondary vortices over the delta wing at angle of attack; the spiral vortical structure developing at transition over the disk; azimuthal structures arising for certain jet conditions; the influence of the channel aspect ratio (width to height ratio) on the heat transfer coefficient distribution along the 180deg turn, as well as the influence of ribs, in the case of static channel; the influence of rotation for the rotating channel.