RU240002U1 - Impeller design with lugs - Google Patents

Abstract

This utility model relates to engine engineering, specifically to centrifugal impellers for gas turbine engines, and can be used in turbochargers and pumps for gas turbine engines. The impeller design, including a main and cover disk, additionally contains balance adjustment projections that protrude axially from the surface of the main and cover disks and are removable. The technical result is more accurate impeller balancing due to the inclusion of a new design element with calculated geometry—balance adjustment projections—in the design, preventing excessive metal removal from the impeller surface and impeller profile changes during operation. 4 clauses, 3 figs.

Description

Field of technology

The utility model relates to engine building, namely to centrifugal wheels of gas turbine engines, and can be used in turbocompressors and pumps of a gas turbine engine.

State of the art

A gas turbine engine's turbine contains a turbine rotor, which converts the kinetic energy of the combustion gases into torque. The turbine rotor balance must be adjusted to reduce vibration and energy loss during rotation. Examples of turbine rotor balance adjustments include machining a portion of the turbine rotor component, which can result in excessive metal removal from the impeller surface and alter their profile.

A well-known impeller design (V. B. Shnepp, "Design and Calculation of Centrifugal Compressor Machines," Moscow, 1995, pp. 99-100) comprises a main and cover disk with blades installed between them. The surface of each blade is designed as a rotating surface, with the axis of the rotating surface parallel to the impeller axis. A disadvantage of this known centrifugal compressor impeller is its insufficient balancing accuracy, which can lead to uneven loading and reduced efficiency due to increased drag losses.

The prior art discloses an impeller for a submersible centrifugal pump (patent RU 11277) made from an antifriction heat-resistant composite with a locking connection formed by grooves in the cover disk with projections in the carrier disk, which is subsequently fixed by melting.

This submersible centrifugal pump impeller does not take advantage of the balance adjustment ring as a means of minimizing axial loads and vibrations. This design can result in insufficient dynamic stability, which negatively impacts the pump's reliability and efficiency, especially under changing operating conditions.

As a technical solution closest to the claimed invention (prototype), a centrifugal pump impeller is proposed according to patent RU 89878, which contains a carrier disk with blades provided with projections that enter the grooves of the cover disk, while the carrier and cover disks are connected to each other by welding.

The prototype's technical problem is insufficient aerodynamic optimization, which leads to increased hydraulic losses and reduced efficiency. Furthermore, the lack of axial load compensation mechanisms can lead to increased vibration during operation, negatively impacting the reliability and service life of the device. The design also fails to address dynamic balancing requirements, posing a risk of premature wear of bearings and other mechanical components.

A common drawback of traditional design analogues is the lack of adaptive mechanisms for dynamic balancing, which limits their performance under changing operating conditions and increases the likelihood of mechanical damage.

The technical challenge is to create an improved impeller design that provides dynamic balancing.

The technical result is to ensure more accurate balancing of the impeller by including a structural element with calculated geometry - balance adjustment projections, which ensure the elimination of excessive metal removal from the surface of the impellers and changes in the profile of the impellers during operation.

Revealing the essence

Impellers are crucial components of gas turbine engines. The most widely used impeller is the closed-type impeller, which consists of a main and cover disk with blades located between them. This type of design can be developed for a wide range of components, including both low- and high-flow impellers.

Impellers operate under stress and strain due to the combined effects of gas flow and centrifugal forces. The overall efficiency of a centrifugal compressor unit depends on the impeller's efficiency. These circumstances make it particularly important to ensure proper balancing through an optimized impeller design with lugs.

Brief description of the drawings

Fig. 1 – General view of the impeller with projections;

Fig. 2 – Protrusions with the stated geometric parameters;

Fig. 3 – Section of the impeller on the axis of rotation.

The figures presented show:

1 – impeller;

1.1 – main disk;

1.2 – cover disk;

2 – balance adjustment projection;

a – impeller diameter;

b – width of the impeller at the outlet;

c – height of the protrusion;

d – width of the projection.

Implementation

Impeller 1 of a gas turbine engine with a diameter of a comprises a main disk 1.1 and a cover disk 1.2, with blades installed between them. The impeller is mounted on a machine tool so that the rotor's axis of rotation is horizontal. At the edge furthest from the axis of rotation, the impeller has an outlet width of b.

At the stage of manufacturing the impeller 1, a balancing adjustment of the measurements is carried out on a balancing machine (not shown), and in order to achieve balance, the residual imbalance is eliminated by removing material from special projections 2 on the impeller 1, which protrudes in the axial direction and can be removed for balancing purposes.

The projections 2 have the geometric shape of a ring located on the outer peripheral sections of the impeller disks, the center of which is the rotor rotation axis, in section the projections represent a rectangle in which the parameters c are the height of the projection, d is the width of the projection, while it has been experimentally confirmed that the technical result is achieved by using special projections in the impeller design, the geometric dimensions of the projections are in a linear relationship with the geometric parameters of the impeller - diameter a and width b, where

c=(0.01-0.02)a,

d=(0.1-0.2)b.

If the protrusion sizes are smaller than those specified in the dependence, based on preliminary modeling and confirmed by experimental studies, the subsequent balancing stage encounters the problem of being unable to eliminate the residual imbalance by removing metal from the protrusions alone. Metal removal from the surfaces of the impeller's main and cover discs becomes necessary. If the protrusion sizes are larger than those specified in the dependence, based on preliminary modeling and confirmed by experimental studies, the imbalance from the protrusions themselves begins to affect the impeller's balancing, introducing additional imbalance that must also be eliminated.

In the preferred embodiment, two annular balance adjustment lugs are located symmetrically on the disks on the outer periphery of the main and cover disks, projecting axially toward the impeller so that their center is the rotor's rotation axis. The recommended geometric parameters of the balance adjustment lugs are c = 0.011a and d = 0.15b to achieve optimal dynamic balancing. The lug material matches that of the impeller's main and cover disks and is manufactured by jointly machining the impeller assembly, leaving an additional allowance on the surfaces of the main and cover disks, with a size corresponding to the developed relationship.

The impeller design with balancing lugs allows for metal removal from the lugs during balancing adjustment, eliminating excessive metal removal from the impeller surface and impeller profile changes, thereby ensuring more accurate balancing. Impellers with balance adjustment lugs used in gas turbine engine designs significantly improve the accuracy of dynamic impeller balancing during operation.

Claims (1)

The design of the impeller, including the main and cover disk, characterized in that the impeller has a diameter a and at the edge, maximum distant from the axis of rotation, has a width at the outlet b, wherein the wheel contains two balance adjustment projections, having the shape of a ring, located on the disks symmetrically on the outer peripheral section of the main and cover disks, protruding in the axial direction of the impeller so that the center is the axis of rotation of the rotor, in section the projections represent a rectangle with the parameters c - the height of the projection, d - the width of the projection and have dimensions that depend on the geometric parameters of the impeller: c = (0.01-0.02) a, d = (0.1-0.2) b, wherein the projections are made with the possibility of removal.