GB1457839A - Turbodrill - Google Patents

Abstract

1457839 Hydraulic turbines VSESOJUZNY WI INST BUROVOI TEKHNIKI 12 Dec 1974 53736/74 Heading FIT The invention relates to a well-drilling turbine of the kind mounted at the bottom of a drill-string and operated by drilling mud. The turbine comprises a shaft 4 on which are mounted a series of rotor elements 5 having blades 6 which co-operate with stator elements 2 secured within the housing 1 and which have blades 3. The rotor and stator blades are formed so that angle 0 formed between tangents to the medium line of the blade profile at the leading and trailing edges of the blade is equal to 180 degrees - (4À5 to 7)α 1 where α 1 is the angle between the axis of the blade row and the tangent to the medium line of the profile of the blade at the leading edge thereof. The angle α 2 between the axis of the blade row and the tangent to the medium line of the blade at the trailing edge is given by (3.5 to 6)α 1 . The ratio of the maximum thickness of the blade profile (#) to the blade chord l is given by (0À09 to 0À19). The tool-holder shaft 8 is rotatably mounted within an outer fixed casing 7 by means of radial bearings 9; the device h defines a labyrinth passage through which exhaust drilling fluid flows, any solid particles being separated out and discharging through passages into the interior n of the tool-holder; cleaned working fluid passes through passages of the bearing 9 acting as a lubricant.