LAST TURBINE STAGE Russian patent published in 2023 - IPC F01D25/32 F01D9/04 F01D5/14 

FIELD: power engineering.

SUBSTANCE: invention relates to the field of power engineering, in particular steam turbine building, and can be used in the design of the last stages of steam turbines with a diaphragm and an impeller, mainly wet steam turbines. The last stage of the turbine contains a flow part with a diaphragm, having a rim with a moisture trapping element and guide vanes arranged with a uniform pitch in the tangential direction, and an impeller with working blades. Guide vanes and working blades have an aerodynamic profile with root and peripheral ends and with leading and trailing edges. An additional moisture trapping element is installed on the rim, and from the side of the steam inlet in front of the peripheral part of the guide vanes, a moisture-removing element with an annular groove is installed, located at an axial distance from the leading edges of the guide vanes, which is in the range of 0.005-0.015 of the height of the aerodynamic profile of the guide vanes. The inner surface of the moisture-removing element on the side of the flow part is made in the form of a part of a convex toroidal surface smoothly conjugated with the conical surface of the rim adjacent to the peripheral ends of the guide vanes. The rotor blades are installed with an axial clearance between their leading edges and trailing edges of the guide vanes in such a way that the ratio of the pitch to the axial clearance increases monotonically from the root ends along the height of the aerodynamic profile of the guide vanes and reaches a maximum value in the range of 2.3-2. 6, in a section whose height is 0.4-0.6 of the airfoil height, and further, to the peripheral ends, it decreases monotonically.

EFFECT: increasing the internal relative efficiency of the last stage of the steam turbine and, accordingly, the internal relative efficiency of the steam turbine, reducing the erosion wear of the rotor blades in the stage.

1 cl, 3 dwg