Abstract: A hydraulic multistage turbine each stage of which comprises a stator and a rotor having rings with flow channels and hubs carrying the bladings. There are stages wherein the blades of the bladings are made with an angle of curvature of the camber line greater than an angle formed by the tangent to this line at the exit of the blading and the axis of drilling fluid flow. In a stage wherein the ring has such blades it is provided with by-pass channels arranged hydraulically parallel to the flow channel of the ring and communicating the space between this ring and an upstream ring with a space between this ring and a downstream ring for discharging part of the drilling fluid from the flow channel.

Abstract: A turbodrill multistage turbine each stage of which comprises a stator and a coaxially disposed rotor. Each stator and rotor are provided with a respective spacing sleeve and a respective ring with respective flow channels and hubs. The hubs carry respective bladings disposed in the flow channels so that there are formed respective radial clearances between the ring of the stator and spacing sleeve of the rotor, and also between the ring of the rotor and spacing sleeve of the stator. At least in a number of rings the hubs are made such that there are pairs of adjacent rings in which at least a preceding (upstream) ring partially overlaps by its hub the flow channel of a subsequent (downstream) ring on the side of the radial clearance thereof.