RU117536U1 - CENTRIFUGAL COMPRESSOR OPERATING WHEEL - Google Patents

Abstract

1. Object of technical solution: Impeller of a centrifugal compressor. 2. Scope: Centrifugal compressors of gas turbine engines, especially aircraft. 3. The essence of the technical solution: The impeller of a centrifugal compressor, which includes a carrier disk, interconnected with the blades. The surface of the profile of the feather of each blade along the line of the periphery of its feather is interconnected with a shelf with a pointed edge. The specified shelf of each blade is made on the side of the rarefaction surface of the surface profile of its pen. At the same time, each indicated shelf with a pointed edge has a Δ-shape in its cross section, and with the indicated rarefaction surface of each blade, the shelf is interconnected with its base along its entire length, meaning its D-shape in its cross section. The specified shelf with its Δ-shaped in its cross section of the inventive impeller of the centrifugal compressor is performed with a calculated increase in its cross section from the inlet to the outlet section of the blade, depending on the size and operating conditions of the impeller. 5. Technical result: Increasing the efficiency of the compressor, the stiffness and strength of the impeller blades, while eliminating the risk of oncoming contact between the blades and the body parts, as well as minimizing damage to the impeller blades during the running-in of the assembly parts, which generally increases the efficiency and durability compressor operation. 1 n.p. f-ly; 2 s.p. f-ly; 3 ill .; 1 ave.

Description

The claimed technical solution relates to the rotors of centrifugal machines, especially compressors, and, in particular, to the impellers of those, taking into account the peculiarities of the geometry of their blades, and is intended for use in high-speed centrifugal compressors of gas turbine engines, especially aircraft.

A semi-open impeller of a centrifugal compressor is known, which contains a carrier disk with interconnected last axial and dividing vanes (see Kampsti N., “Aerodynamics of compressors”, M., “Mir”, 2000, p. 101, Fig. 2.16).

The disadvantage of such impellers is the significant deformation observed at high circumferential speeds of rotation (more than 500 m / s), which requires either a thickening of the carrier disk or the use of large gaps between the stationary body and the blades, and this leads to an increase in the mass of the impeller or overflow of the impeller, respectively. body in the gaps and reduces the efficiency of the compressor.

From the description of the copyright certificate of the USSR No. 189315, cl. IPC F05C (59B, 1) was declared on 11/17/1966, the impeller of a centrifugal pump is known.

It was an attempt to simultaneously obtain the combined technical result of increasing the efficiency of the device and increasing the rigidity of the structure by means of certain improvements consisting in the aggregate of the trough-shaped blades in the direction of rotation of the wheel and the connection of their annular rim.

It should be noted that such a solution is really useful in light and medium loaded centrifugal wheels, however, the efficiency in high loaded structures and, in particular, in aircraft engines is insufficient.

The technical solution "Radial flow turbomachine" by General Motors Corp. is also known. (see US patent No. 3 984193, claimed 07.10.1974, class. USA 415/213/219, class. IPC F04D 17/00), which presents a centrifugal compressor.

The periphery of each of its blades along and from the inlet of the pressure surface to the outlet has a flange or “lip” at the front cover of the compressor.

Moreover, its claimed technical result is to minimize leakage of the working fluid between the cover and the edges of the blades adjacent to it.

It should be noted that in his work, leakage reduction does occur, but the turbulence arising from this reduces the efficiency of the solution.

From the description of the USSR author's certificate No. 1603073, F04D 29/28, declared 05/10/1988, the impeller of a centrifugal supercharger is also known, which contains a carrier disk 1 with blades 2, each of which has axial 3 and radial 4 sections of the surface of the pen profile. The periphery of each blade 2 on the radial section 4 of the surface of the profile of the pen is equipped with a shelf 6 of the estimated length. Shelf 6 has an edge 7 of indefinite shape, oriented in the same direction as the pressure surface 8, called the working surface, which is part of the surface of the pen profile. In the same place, on the radial sections of the blades, named as ends, grooves 10 are made, which technologically provide the formation of shelves 6.

This well-known technical solution allows to reduce the overflow of the working fluid in the gaps between the blades and the stationary body due to the tightening of the end part of each blade and the presence of grooves that act as an air seal. However, it also has several disadvantages.

Under the influence of centrifugal forces, the shelf deflects in the direction of the fixed body, while a possible touch with a pointed edge on the fixed body has a counter character, which entails incision into the surface of the body. Open grooves on the end parts of the blades contribute to an increase in recirculation losses, in which the working fluid, exiting from the interscapular channel with high pressure, flows along the above grooves to the entrance to the impeller in the direction of lower pressure, which also leads to loss of wheel performance.

Nevertheless, due to the commonality of essential features with the claimed, the technical solution for the security document SU No. 1693073 "Impeller of a centrifugal supercharger" can be used as a prototype.

The authors were faced with the task of creating such a rotor of a centrifugal compressor in which losses due to overflow of the working fluid in the gap between the blades and the stationary casing would be minimized, and at the same time to obtain a certain aggregate technical result containing several, logically interconnected, technical results.

The main technical result is to increase the efficiency of a high-speed compressor by reducing losses from overflow of the working fluid.

In this case, the technical result of ensuring the stiffness of the blade pen should be obtained while optimizing the natural frequencies of its vibrations and, as a result, preventing the destruction of the device.

The problem is solved in that in the known impeller of a centrifugal compressor containing a bearing disk interconnected with the blades, the surface of the profile of the feather of each of which from the input section to the output along the periphery of its feather (see GOST 23537-79, p. 14) is equipped an additional shelf with a pointed edge, an improvement is made.

The improvement lies in the fact that the shelf with the pointed edge of each blade along the line of the specified periphery of the pen surface of the profile of the pen is made on the side of the rarefaction surface

Moreover, this shelf is made Δ-shaped with its base, interconnected with the specified surface of the rarefaction of the scapula.

In addition, the specified Δ-shaped shelf is made with a smooth increase in its cross section from entrance to exit based on well-known calculation methods and the size of the gas-dynamic loads of the selected wheel.

The claimed technical solution is illustrated by drawings, where:

- figure 1 is a view of the inventive impeller of a centrifugal compressor, with a partial longitudinal section and a possible set of blades as full axial and calculated shortened dividing with the mentioned Δ-shaped shelf;

- figure 2 shows the remote element A, a separate enlarged image of the blades of the impeller;

- figure 3 shows an image of a conditionally disconnected Δ-shaped shelf. The impeller 1 (see Fig. 1) of the centrifugal compressor contains a carrier disk 2 and interconnected axial-radial vanes 3 and, if possible, dividing vanes 4. Moreover, each of the aforementioned vanes has a pressure side 5 and a rarefaction side 6. As on axial radial vanes 3 and on the dividing blades 4 along their entire estimated length from the rarefaction side 6 on the line 7 (see FIG. 2) of the feather periphery, a Δ-shaped shelf 8 is made, which is a protrusion of the body of the blade’s feather with the base 9, which is part of the surface spacing 6 of the pen profile, an additional increase of 10 thickness of the pen in the circumferential direction and pairing 11 of the pointed edge 12 with the side of the rarefaction 6 of the pen profile.

Depending on the size of the wheel, the aforementioned additional increase in 10 thickness of the pen (value B) is determined by calculation, but it is maximum at the output edge 13 and gradually decreases (see Fig. 3, B <B ′ <B ″) in the direction to the input edge 14 and the root part 15 of the impeller 1 for both axial-radial blades 3, and for separation 4, if necessary according to gas-dynamic requirements and calculations.

When the centrifugal compressor is working, the kinetic energy of the rotating impeller 1 is transmitted to the working fluid entering the interscapular channels (see Fig. 1). The existing pressure difference of the working fluid in the interscapular canal causes secondary flows perpendicular to the main flow, which are directed from the pressure side 5 to the rarefaction side 6, as well as from the root part 15 to the periphery of the impeller feather 1. In this case, shelf 8 with a pointed edge 12 ( see Fig. 2) directs, by conjugation 11, the above flows parallel to the boundary layer on the fixed casing, thereby contributing to the reduction of vortex loss during mixing.

Under the influence of centrifugal forces and temperature, the impeller 1 has elastic deformations, which lead to a decrease in the gap between the stationary body and rotating both axially radial 3 and dividing 4 vanes. In this case, the possible contact of the shelf 8 with a pointed edge 12 about the stationary body will have a passing character.

According to the technical solution presented in the description, prototypes of the impeller of a centrifugal compressor were manufactured, which were tested in the profile of a real aircraft gas turbine engine, which confirmed the operability and the claimed technical result.

Thanks to the proposed technical solution, the compressor efficiency, the stiffness and strength of the impeller blades are increased, and the counter-contact of the blades on the body parts is excluded, and damage to the impeller blades during running-in is minimized, which generally increases the efficiency and durability of the compressor.

Claims (3)

1. The impeller of a centrifugal compressor containing a bearing disk with blades, the profile surface of the pen of each of which is provided along the periphery of its feather from the entrance to the output with a shelf with a pointed edge, characterized in that the shelf with a pointed edge of each blade along the specified line of the pen is made on side of the rarefaction surface of the specified surface profile of the pen. 2. The impeller according to claim 1, characterized in that the said shelf is made Δ-shaped with its base interconnected with the specified surface of the rarefaction of the scapula. 3. The impeller according to claim 2, characterized in that said Δ-shaped shelf is made with an increase in its cross section from the inlet to the outlet section of the blade.