Гидродинамика

370 а m o d i f i c a t i o no f k i r c h h o f f ' s m e t h o d infinitely distant points has in the relative motion a direction at right angles to the axis of the lattice. Owing to this, in solving- the problem of turbines the analysis given has to be modified as stated in the Appendix by Prof. S. A. Tchapligin and A. P. Minakoff. Joukowsky's method completely solves the problem of the strea ­ ming of a fluid past rectilinear contours with a sweeping away of the currents. ;Almost simultaneously with Joukowsky's work there appeared that of Micbell „On the Theory of Free Stream- Lines" (London, 1890), in which some of the problems solved by Joukowsky are solved by Kirchhoff's method combined with the conformal transformation of Christoffel-Schwartz. Nevertheless with Prof. Joukowsky's method rests the advantage of greater convenience. Joukowsky concludes his work by the following words; „А certain modification of the function ф{и) makes it pos ­ sible also to solve the problems of the impact of an infinite stream against bodies bounded by curvilinear contours, and of the efflux from vessels with convilinear walls. We have solved some of such problems but did not succeed in obtaning contours 'of simple form. Thus, we were unable, notwithstanding prolonged investigations, to solve the problem of impact of an infinite stream against a circular cylinder. Perhaps this problem might be solved as the limiting case of the problem of the impact of a stream against a polyhedral contour, the salient angles giving,, in passing t o the limit, a finite value for the velocity".