Measurement of Mean Particle Sizes of Sprays from Diffractively Scattered Light

Abstract

by the radiator area given by its overall dimensions multiplied by vT In face of these irregularities existing in a machined grooved surface, the error introduced by the first three assumptions will be small for all practical purposes. However, it might become significant at very small angles, i.e., smaller than 10°.' It should be kept in mind that the depth of the grooves should be kept small so that the walls remain isothermal. To make the grooves too small, however, introduces new difficulties. The roundness at the top becomes significant; therefore, the surfaces of the grooves, on the average, are out of flat. Here again, experiments have indicated that, if (r/d) < 5%, the relationships discussed hold well. In conclusion, it can be stated that the application of V-shaped grooves on a metallic surface will increase its thermal emissivity in a practicable manner. The assumptions made initially are justified for all practical purposes, considering the difficulties presented in the analysis when assumptions 1-3 are dropped. It is important to point out that a groove of less than 45° angle provides apparent emissivities two to four times greater than the surface emissivities. For base metals this is quite significant, since most of them exhibit total thermal emissivities of less than 0.2.