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Wielosektorowy promiennik podczerwieni

Polakowski H., Piątkowski T., Dulski R., Firmanty K., Morawski M.

Pomiary Automatyka Kontrola

2009

R. 55, nr 11

894-897

W pracy zaprezentowano wielosektorowy, promiennik podczerwieni, który może być wykorzystany przy badaniach rozdzielczości temperaturowej kamer termowizyjnych. Powierzchnia promieniująca zawiera sekto-ry o różnych współczynnikach emisyjności wykonane z mikrownęk. Umieszczenie wielosektorowego promiennika podczerwieni w odpowied-nio zaprojektowanej osłonie termicznej umożliwia przestrajanie kontrastu sąsiadujących ze sobą sektorów z rozdzielczością bliską 100mK.

The paper presents a multi-sector, highly stable IR source that can be used for (MRTD) testing thermal cameras. The proposed solution is based on a single, monolithic multi-sector IR source with areas of different emissivity. As a result of the emissivity difference, the particular sectors are imaged by thermal camera as areas of different temperatures. The sectors exhibit the radiative properties of a gray body. They are manufactured as micro-cavity structures in a solid metal plate. The desired value of emissivity is achieved by adjusting the geometric parameters of microstructure. The thermal contrast between adjacent sectors is obtained by selecting different effective emissivity values for particular sectors. By placing the multi-sector source inside a thermally insulated case it is possible to tune the thermal contrast between the adjacent sectors with 100 mK resolution. The emissivity of microstructure comb patterns was measured by a thermal camera. The temperature characteristics as well as the relation between the effective emissivity and the shape coefficient of a microstructure were determined. The designed IR source has the uniform radiative temperature distribution across its surface.

Thermal radiation of an optically thin gray gas in the presence of indirect natural convection

Ghosh S. K.

International Journal of Applied Mechanics and Engineering

2007

Vol. 12, no 3

593-598

The effects of thermal radiation on the flow of a viscous incompressible fluid occupying a semi-infinite region of space bounded by an infinite horizontal moving hot plate in the presence of indirect natural convection by way of an induced pressure gradient, is considered. The fluid is a gray, absorbing-emitting radiation but a nonseattering medium. An exact solution is obtained for the flow by applying the Laplace transform technique. The numerical results of velocity distributions are depicted graphically for different values of radiation parameter K1 and Grashof number Gr, taking the Prandtl number Pr=0.71 and t=0.2 are kept fixed. It is observed that the velocity slightly decreases with increasing the value of radiation parameter while the velocity is slightly decreases with an increase in Gr whereas there exists a reverse flow on increasing Gr due to the presence of the induced pressure gradient.