On the effect of geometry of cooled boundaries of structural elements of electrophysical devices under cyclic thermal loading

A non-stationary thermal field of a surface element with built-in cooling channels under one-side cyclic heat flow loading is considered. The cooling channels are in the form of tubes built in the thin-walled construction of a diameter considerably greater than the wall thickness. In one-dimensional approximation an analytical solution is obtained for boundary conditions of the third type (BC), as well as for modified BC when the cooling medium temperature is a linear function of time (sawtoothed). A comparison of the one-dimensional problem results with those of the numerical two-dimensional problem for an initial profile obtained by net methods is amade for the vacuum chamber of the T-20 demonstration thermonuclear tokamak-reactor. An accumulative influence of the lower parts of cooling channels has been shown. The conclusion is made that the one-dimensional approximation in the calculation of the profile gives the acceptable results only for the cases when the mass surface of the developed cooling zones are small in comparison with the bulkhead body. Otherwise, and especially at high temperatures the necessity of transfer to the two-dimensional solution with provision for emission appears