RU177044U1 - Split hollow disc - Google Patents

Abstract

The utility model relates to the field of aeronautical engineering, namely to split hollow disks and can be used in the manufacture of turbine disks for gas turbine engines. The proposed utility model reduces stresses by eliminating stress concentrators in the design of a split hollow disk, which as a result allows us to solve the problem of increasing the long-term structural strength of a split hollow disk during operation, while maintaining the conditions for reducing the mass of the disk. The essence of the utility model consists in the placement of inserts in the through radial slot of the hub of the hollow disk made in the form of segments of a split ring, fitted with an interference fit and with emphasis in ring collars made on the inner surfaces of the hub slot facing each other. The width and height of the shoulders and segments is in a certain dependence, respectively, on the width of the rim and the height of the hub of the disk. 4 ill., 1 tab.

Description

The utility model relates to aeronautical engineering, namely to split hollow disks, and can find application in the manufacture of turbine disks for gas turbine engines.

Increasing the strength of the disks and reducing their mass is possible due to the optimization of their structural appearance, the use of new materials and / or the use of new structural and technological solutions.

One such solution is a hollow disk, including a rim, webs and a hub.

In most cases, well-known technical solutions suggest using a hollow disk design for supplying cooling air to the blades through the hub along the cavity between the webs and then through the vertical holes in the rim. However, the holes in the hub and rim create stress concentrators, which significantly reduce the static and cyclic strength of the disk. A significant drawback when using a hollow disk for supplying cooling air to the blades is the amount of air that is insufficient for proper cooling, which can be supplied through the space between the shaft (low or medium pressure) and the hub of the turbine disk into the hole in the hub. For this, it is necessary to reduce the diameter of the shaft, which leads to a decrease in its strength and to the need for a significant revision of the circuit of the entire engine.

Another area of application of the hollow structure is to reduce the mass of the disk due to the separation of the canvas into two parts and their optimal location along the rim, which ensures uniform transfer of the contour load to the hub. This allows you to reduce the size of the latter and reduce the weight of the impeller as a whole.

A known rotor of a turbomachine containing a split hollow disk, including a rim, blades and a hub (SU 1201528, 1985). The design of the disk in the known technical solution provides the possibility of separate manufacture of its elements using traditional technologies, followed by a rigid connection by welding, which can significantly reduce the mass of the disk. A disadvantage of the known technical solution is the complexity of processing the inner surface of the cavity of the disk after connecting the structural elements of the disk, as well as the strength and quality of the weld.

A multi-sectional split hollow disk is known, including a rim, webs and a hub with a through radial slot (US 4102603, 1978). In a known technical solution, the disk is made in the form of a set of canvases that are fastened together by bolted joints in the middle of the canvases and in the rim, while the hubs of the disks contact freely. To form a cavity in the area of bolt connections, the sheets are thickened, which allows you to evenly transfer the load from the rim to the hub, as well as improve heating. A disadvantage of the known technical solution is the presence of holes for bolted joints that reduce the strength of the disk.

Known split hollow disk, including the rim, the blade and the hub with a through radial slot (US 5961287, 1999). In a known technical solution, bushings are provided in the slot of the hub for supplying cooling air. A disadvantage of the known technical solution is the presence of stress concentrators in the form of bushings. In addition, the increased mass of the hub leads to an increase in axial stresses, to a deterioration in the heating of the hub and, as a consequence, to an increase in temperature stresses.

The closest in technical essence and purpose to the proposed utility model is a split hollow disk, including a rim, webs, a hub with a through radial slot and inserts placed in a radial slot of the hub (US 3982852, 1976). In the known technical solution, the inserts are used to organize the supply of air into the cavity between the webs, as well as to prevent the closure of the hub halves under the action of centrifugal forces. At the same time, the issue of assembling the structure is not considered, since there is no explanation of how the inserts are inserted into the slot of the hub. The trailing insert is difficult to install because the circumference of the upper surface will be greater than the available free space. In this case, the inserts are not fixed in the radial and circumferential direction, which, in the absence of load, leads to the fact that the inserts can freely move and fall out of the slot. In addition, in the known technical solution, the inserts contain through holes for supplying cooling air, which are voltage concentrators, i.e. a significant disadvantage of the known technical solution is the lack of structural strength.

Thus, the known technical solutions ensure that the conditions for reducing the mass of the disk are met. A common significant drawback of the known technical solutions is the insufficient level of static and cyclic strength of the disk structure during operation, due to the presence of stress concentrators.

The technical problem solved by the creation of the claimed utility model is to increase the long-term structural strength of the split hollow disk during operation while maintaining the conditions for reducing its mass.

The technical result provided by the proposed utility model is to reduce stresses by eliminating stress concentrators in the design of a split hollow disk.

The claimed technical result is achieved in that in a split hollow disk, including a rim, webs, a hub with a through radial slot and inserts placed in a radial slot of the hub, persistent annular collars are made on the inner surfaces of the hub slot, the width and height of which is in the range from 0.1 to 0.3, respectively, of the rim width and height of the hub of the disk, the inserts are made in the form of segments of a split ring, the width and height of which is in the range from 0.3 to 0.5, respectively the width of the rim and the height of the hub of the disk, the segments are placed in the slot with an interference fit and with an emphasis on the collars, and on the inner radial surface of the segments of the split ring there are made radial grooves in which the expanding ring is placed.

The set of essential features is sufficient to solve the specified technical problem and achieve the claimed technical result.

The implementation of the inserts in the form of segments of a split ring, placing the segments in the slot with interference and with emphasis on the collars, the execution on the inner radial surface of the segments of the radial grooves in which the expanding ring is located, simplifies the process of assembly of the disk, provides fixation of the segments in the slot of the hub and eliminates the possibility closing the edges of the slot under the action of centrifugal forces, which ensures an increase in the long-term strength of the design of the split hollow disk due to the exclusion of stress concentrators while maintaining the conditions for reducing its mass during operation.

The execution on the inner surfaces of the slot of the hub facing each other of persistent annular collars, the width and height of which is in the range from 0.1 to 0.3, respectively, the width of the rim and the height of the hub of the disk, and the choice of the width and height of the segments in the range from 0.3 to 0.5, respectively, the width of the rim and the height of the hub of the disk provide increased long-term structural strength of the split hollow disk due to the exclusion of stress concentrators.

The proposed technical solution is illustrated by the following detailed description of the design of the split hollow disc and its operation with reference to FIG. 1-5, where:

- in FIG. 1 shows a diagram of a split hollow disc;

- in FIG. 2 shows a layout of an expanding ring in grooves of segments;

- in FIG. 3 shows a diagram of a typical optimized disk;

- in FIG. 4 shows a stress distribution diagram as a result of optimization of disk designs (a - standard configuration; b - solid hollow configuration with a slot; c - disk configuration in accordance with the proposed utility model);

- in FIG. 5 is a table of comparative optimization results.

Split hollow disk includes a rim part 1, the blade 2 and the hub 3, forming an internal cavity 4 (see Fig. 1, 2). In the hub 3, a through radial slot 5 is made, and on the inner surfaces of the slot 5 facing each other, corresponding thrust annular collars 6 are made. In the radial slot of the hub 3 there are inserts made in the form of segments 7 forming a split ring. The segments 7 are placed in the slot 5 with an interference fit and with an emphasis on the collars 6. On the inner radial surface of the segments 7 there are made radial grooves 8 in which the expanding ring 9 is placed.

Assembling a hollow split disk design is as follows. In the radial slot 5 of the hub 3, the segments 7 are sequentially placed in the annular collars 6 until they stop. In order to prevent the segments 7 from turning in the circumferential direction during engine operation, they are installed with a slight tightness relative to the end internal surfaces of the hub 3. Analysis of the experimental data showed that the recommended value preload is from 3 to 5 microns. In the process, segments 7 will be compressed by the internal surfaces of the slot 5, the edges of which, under the action of centrifugal forces, tend to come closer to each other. An interference fit guarantees the absence of circumferential displacements of segments 7, both in the presence of load, and in its absence. After installing the segments 7, they are fixed in the radial direction using the expanding ring 9.

The boundaries of the sizes of segments 7 and shoulders 6 are determined by the requirements for ensuring the strength conditions, technological and structural limitations. The geometric dimensions of the segments 7 and thrust ring collars 6 are determined relative to the width of the rim 1 of the disk and the height of the hub 3. The width and height of the collars 6 are in the range from 0.1 to 0.3, respectively, the width of the rim 1 and the height of the hub 3 of the disk, width and height segments 7 is in the range from 0.3 to 0.5, respectively, the width of the rim 1 and the height of the hub 3. Moreover, the specific dimensions for each design are determined within the specified limits during the design process using parameterized models and multicriteria optimal methods tion. The dimensions of the expanding ring 9 are determined structurally, its geometric dimensions are selected relative to the values of the width and height of the segments 7.

Example. An analysis is made of the advantages of the split hollow disc design described in the proposed utility model compared to the use of a solid hollow disc and a standard (single blade) configuration in terms of weight reduction. For this, the design of a typical turboprop engine disk was optimized for the three proposed types of structures.

The overall dimensions of the optimized disk are shown in FIG. 3.

Disk conditions:

- rotation speed - 30000 rpm .;

- contour load on the rim - 180 MPa;

- temperature difference hub-rim: 180-650 ° C;

- disk material - nickel alloy.

The optimization objective is to ensure the long-term strength of the disk, provided that its mass is minimized.

The following conditions are used as limitations:

- the level of equivalent stresses according to Mises in the disk (zone of the hub, webs and rim) is not higher than 850 MPa;

- the value of the margin of bearing capacity of not less than 1.4.

The stress distribution obtained by optimizing the considered disk designs is shown in FIG. four.

Comparative optimization results of the considered disk designs are shown in FIG. 5, from which it follows that the use of a hollow structure (both split and solid) for a given disk allows its weight to be reduced by 12%. Moreover, the stress level in different types of disk structures is the same. The dimensions of the hubs of the optimized hollow discs are larger than the dimensions of the hubs of the optimized disc of a standard configuration, but they do not exceed the size of the overall size of the optimized disc of a standard configuration (60 mm).

An analysis of the strength of the split ring segments using a 3D finite element model of the entire disk shows that dangerous stresses do not occur in the disk, the expanding ring works in the elastic region. Since a split hollow disk has a complex topology (curved canvases, the complex design of ledges and hubs, etc.), it is necessary to use automated parameterized models and modern multi-criteria optimization methods for design.

Thus, the proposed utility model reduces stresses by eliminating stress concentrators in the design of the split hollow disk, which as a result allows us to solve the problem of increasing the long-term strength of the design of the split hollow disk during operation while maintaining the conditions for reducing the mass of the disk.

Claims (1)

Split hollow disk, comprising a rim, webs, a hub with a through radial slot and inserts located in the radial slot of the hub, characterized in that persistent annular collars are made on facing inner surfaces of the hub slot, the width and height of which are in the range from 0.1 to 0.3, respectively, of the width of the rim and the height of the hub of the disk, the inserts are made in the form of segments of a split ring, the width and height of which is in the range from 0.3 to 0.5, respectively, of the width of the rim and the height of the hubs disk, the segments are placed in slots with interference and with a focus in piles, and on the inner radial surface of split ring segments provided with radial grooves, in which the spreader ring taken.

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