SE308491B - - Google Patents

Abstract

995,178. Hydraulic turbines. J. M. VOITH G.m.b.H. May 21, 1963 [May 22, 1962], No. 20128/63. Heading F1T. An admission system for hydraulic reaction turbine such as Kaplan and Francis turbines comprises an annulus of guide vanes, an intake duct merging into a spiral casing and a cusp formed by the inner wall of the intake duct and the end of the outer wall of the spiral casing, characterized in that the cusp forms a wall with its concavity facing the turbine axis and of thickness not exceeding three times the thickness at its outlet end, the length of the cusp being between 30 to 80 times the thickness at its outlet end, disregarding any final taper forming the extreme terminal edge. A Kaplan or Francis turbine intake duct 1, Fig. 1, merges into a spiral casing 2 to form a cusp 10 between the outside wall 6 of the casing 2 and the inner wall 5 of duct 1. The thickness of the cusp 10 does not exceed three times the thickness at its outlet 11, disregarding the taper 11 a, and its length is between 30 and 80 times, preferably 50 times, this outlet thickness. The form of the spiral 2 is such that the mean peripheral velocity of flow increases between radial planes a and c, decreases between c and e, and increases between e and a. The camber and chordwise length of the guide vanes 18 to 28 decrease in the direction of flow and vanes 18, 19 may have a chordwise length between 2 and 3 times that of the following vanes. The distance between consecutive vanes 18 to 28 may increase from the cusp 10 onwards and the distance between cusp 10 and vane 18 or between vanes 18 and 19 may be half that between any two other consecutive vanes. In further embodiments the outside wall 30 of the spiral is elliptical, Fig. 3 (not shown) or circular, Fig. 4, and the halves 31a, 31b of the inner wall on either side of the guide vanes 18 to 28 may be inclined by up to 15 degrees. The radius R is not greater than 0À25 times the distance B o . Specification 813,298 is referred to.