부산대학교 도서관

A technique to visualise and measure temperature distributions in gas flows is described which places fine, highly-emissive planar meshes in the heated flow and images them with an IR camera. Fine meshes with high porosity are used to minimise the disturbance to the flow field and ensure that the local mesh temperature is close to the local gas temperature. The radiation received by the camera is a function of both the temperature and the emissivity of the body visualised. In the case of a porous mesh, the camera will visualise both the mesh surface and the background through the mesh apertures. An effective emissivity, which combines the relative area fraction and emissivity of the mesh can be obtained via calibration. This effective emissivity is used to reduce the intensity data to temperature distributions. Attention must be paid to the ratio of the size of the projected camera pixel to the mesh opening size to ensure accuracy. The technique is demonstrated on a number of buoyant jet flows and the potential application of the technique to higher temperature flows is discussed.