RU131814U1 - TURBOMETER RADIAL GAP CELL SEAL - Google Patents

Abstract

A honeycomb seal of a radial clearance of a turbomachine, comprising a turbine stator with a sealing honeycomb surface installed by soldering and a rotor shaft, characterized in that sealing ridges are arranged on the rotor shaft and arranged with a radial clearance opposite the honeycomb sealing surface, while the sealing ridges on the rotor shaft are thickened with a sharp leading edge and an annular groove at the top having a depth of up to 25% of the height of the scallop, the top of the sealing scallop has a slope of 10 ÷ 15º against detecting leakage current main stream.

Description

The utility model relates to the field of turbine engineering and is specifically applicable to diaphragm, over-band, or end seals of a radial clearance of a turbomachine.

The efficiency of modern turbomachines is significantly affected by leakage of the working fluid through the radial clearances between the rotor and stator. Reducing the radial clearance in the seals in order to reduce leaks is not always possible, as this is due to the peculiarities of the operation of the turbomachine during commissioning of full-time operations.

Known labyrinth step seals with sealing combs on the stator and grooves on the shaft, used, for example, for the diaphragms of the flow parts of low pressure steam turbines [Truhniy, A.D. Stationary steam turbines / A.D. Trukhny. - 2nd ed., Revised. and add. - M .: Energoatomizdat, 1990 .-- 640 p. p. 108, Fig. 3.53].

The disadvantages of the known labyrinth seals is that they are characterized by relatively large leaks of the working fluid and are used only for small pressure drops.

Closest to the proposed solution, the labyrinth seal is disclosed in [Utility Model Patent RU No. 90845, IPC F01D 11/02]. The labyrinth seal of the steam turbine according to the indicated copyright certificate contains a shaft with sealing ring ridges of trapezoidal shape and a housing on the inner surface of which are made annular grooves into which the sealing segment rings are inserted. In the segments there are made blind radial holes in which screw compression springs are installed. On the sealing segment rings, fine-mesh honeycomb surfaces made of thin metal foil are installed by soldering. The radial clearance between the sealing ring flanges of the shaft and the honeycomb surface of the sealing segment rings is maintained in the range of 0.15 ÷ 0.20 millimeters.

The disadvantage of this technical solution is the relatively large leakage of the working fluid.

The utility model solves the problem of reducing leakage of the working fluid through a honeycomb labyrinth seal of a turbomachine.

The honeycomb seal of the radial clearance of the turbomachine contains a turbine stator, onto which fine-mesh honeycomb surfaces made of thin metal foil and a rotor shaft are mounted by soldering, on which scallops are made located with a radial clearance opposite the honeycomb sealing surface.

Sealing scallops of the shaft located opposite the honeycomb surface are thickened with a sharp leading edge and have an annular groove at the top with a depth of up to 25% of the height of the scallop. The top of the sealing comb has a slope of 10 ÷ 15 degrees against the direction of flow of the main leakage stream.

A sharp leading edge can be made at the top of the sealing combs to further turbulize the flow.

In the future, the utility model is illustrated by a specific example of its implementation with reference to the accompanying drawings, which depict:

Figure 1 is a longitudinal section of a seal segment;

Figure 2 - node "A" of figure 1 on an enlarged scale.

The honeycomb seal of the radial clearance of the turbomachine contains a stator 1 with an annular groove 2, springs 3, cases of segments 4. On the inner (sealed) surface of the segments 4, a fine-mesh cellular surface 6 made of thin metal foil is fixed using a soldered seam 5. On the rotor shaft 7 there are sealing scallops 8 located with a radial clearance opposite the honeycomb structure 6. The sealing scallops 8 have an annular groove 9 at the top with a depth of up to 25% of the height of the scallop. The top of the sealing ridges 8 is made with a slope of 10 ÷ 15 degrees against the direction of the main leakage flow and has a sharp leading edge 10. The necessary radial clearance is maintained between the honeycomb surface 6 and the ridges 8 of the rotor shaft 7.

The operation of the honeycomb seal of the radial clearance of the turbomachine is as follows. The honeycomb structure 6 on the cases of segments 4 and the sealing combs 8 on the surface of the rotor shaft 7 prevent the flow of the working fluid through the radial clearance in the seal. With multiple throttling and sudden expansion of the working fluid, which occurs when the flow flows sequentially through the gaps and chambers between the sealing combs 8 on the rotor shaft 7, the pressure of the working fluid decreases due to significant hydraulic resistance, which leads to a decrease in leakage through the seal.

When the working fluid gets into the annular groove 9 at the top of the sealing comb 8, which has a slope of 10 ÷ 15 degrees against the direction of the main leakage flow, changes its direction and is thrown into the gap space at an angle to the main flow, contributing to its greater penetration into the cell space cells, increasing the flow friction against the walls of the honeycomb surface and the formation of additional vortices, which, in turn, reduces the axial component of the leakage flow rate, and as a result, the leakage flow rate s seal.

An annular groove at the top of the sealing combs with a depth of up to 25% of the height of the comb allows the energy of the vortex formed in it to be used to block the leakage flow through the radial clearance of the seal.

The honeycomb seal of the radial clearance of the turbomachine is provided with flow turbulization means made in the form of a sharp leading edge 10 at the tops of the sealing scallops 8. The sharp front edge of the scallop provides flow separation during its flow and limiting leakage through the seal.

The advantage of the proposed design of the honeycomb seal is to reduce leakage of the working fluid through the radial clearance, which leads to an increase in the efficiency of the turbomachine as a whole.

Claims (1)

A honeycomb seal of a radial clearance of a turbomachine, comprising a turbine stator with a sealing honeycomb surface installed by soldering and a rotor shaft, characterized in that sealing ridges are arranged on the rotor shaft and arranged with a radial clearance opposite the honeycomb sealing surface, while the sealing ridges on the rotor shaft are thickened with a sharp leading edge and an annular groove at the top having a depth of up to 25% of the height of the scallop, the top of the sealing scallop has a slope of 10 ÷ 15º against detecting leakage of the underlying stream.

Images