RU190525U1 - INPUT DEVICE CENTRIFUGAL COMPRESSOR - Google Patents

Abstract

The device comprises a radial inlet element having opposite walls forming an annular channel. On the periphery of the walls there are rigid trusses in the form of a truss, a protective grid with a U-shaped profile is installed, the inner surface of the wall that forms the air path is made with a tolerable deviation from a theoretically specified value of no more than 0.02 mm. The technical result is the elimination of disturbing factors at the input and in the boundary layer of the channel of the input device.

Description

The invention relates to gas turbine engines (GTE) and, more specifically, to intake devices for compressors of gas turbines.

Uneven distribution of air flow through the intake port of a gas turbine engine compressor can reduce engine performance. This problem is significant for radial inlets. Accordingly, there is a need for a simple device that can provide more uniform air flow for radial entry.

Known input device axial turbines according to the author's certificate on the invention SU 1430609 A1, F04D 29/54, publ. 10/15/1988. The device contains an annular confuser mounted in a radial nozzle having a shell and side walls. The inlet section of the confuser is located to the plane perpendicular to its axis, at an acute angle, the apex of which is facing the nozzle. The inlet section is located from the side wall located on the side of the inlet of the nozzle, at a minimum distance not less than the width of the latter at the inlet. The disadvantage of this device is technological and structural complexity.

The disadvantage is the technological and structural complexity.

Known input device according to patent EP 1733127 B1, F02C 7/055, publ. 04/23/2014. The radial inlet device comprises a radial inlet configured to communicate in fluid with the compressor, and a restricting element encompassing the radial inlet and being circumferentially asymmetrical. The limiting element partially blocks the flow of air around the radial inlet, where the air flow is greater, for a more uniform distribution of air flow around the circumference. The disadvantage of this device is a significant loss of total pressure at the inlet to the compressor.

The prototype of the utility model is the input device of the engine AI-450-MS [Auxiliary gas turbine engine AI-450-MS. Guidelines for the technical operation of the engine 0020000000RE. Section: Gas Generator Compressor Turbine]. The inlet device comprises a radial inlet element having opposite walls forming an annular channel, profiled in such a way that the incoming air flow is radially directed axially into the compressor. Opposite walls are rigidly interconnected by four radial struts. On the periphery of the walls, a protective grid covering the radial inlet is installed.

The disadvantage of the device of the prototype is the presence of disturbing factors in the annular channel. These factors are caused by the presence in the input device of the radial struts having a considerable thickness, which introduces significant disturbances in the air flow. In addition, the construction with the racks is technologically performed by casting, which imposes significant restrictions on the accuracy of the surface of the device walls. The low accuracy of the surface of the walls and the presence of radial struts creates uneven flow at the entrance to the impeller of the compressor.

The task of the utility model is to reduce the uneven flow of air at the compressor inlet, by eliminating disturbing factors at the inlet and in the boundary layer of the channel of the input device.

The task is solved by improving the input device containing a radial inlet element having opposite walls forming an annular channel, shaped so that air flow entering radially is directed axially and has rigid connecting elements between the walls and a protective grid on the periphery of the walls covering radial inlet element.

In accordance with the utility model, the connecting elements are made in the form of a truss located on the periphery of the walls (at the entrance to the annular channel), the truss is made in the form of a triangular lattice, the diagonal of which has a streamlined profile and are uniformly distributed around the perimeter of the inlet channel, and the shape of the protective grid has a U-shaped profile, in addition, the inner surface of the wall forming the air path, is performed with a permissible deviation from the theoretically specified value of not more than 0.02 mm.

In a particular embodiment of the utility model, the geometry of the truss has the following parameters: the angle between the diagonals of the triangular lattice has the value α = 50-60 °, and the ratio of the diagonal width to their maximum thickness matters

where b is the width of the diagonals, mm;

Cmax - diagonal thickness at the maximum, mm.

Distinctive features of the device that affect the technical result are the constructive implementation of the connecting elements of the walls, the accuracy of the wall profile and the constructive implementation of the protective grid. The implementation of the connecting elements in the form of a truss located on the periphery of the walls eliminates disturbing factors in the channel arising in the presence of radial struts, besides encompassing the radial inlet, the truss provides additional rigidity and has the function of a supporting element in contact with large objects. The parameters of the geometry of the farm are the best to achieve a technical result. The claimed design allows the inner walls to be machined with a strictly specified accuracy, ensuring that disturbances in the boundary layer of the channel are minimized. The protective grid, which has a U-shaped profile, has vertical elements, which allows to improve the flow uniformity, especially in icing conditions, since horizontal areas are prone to icing before vertical.

The proposed device is illustrated by the following drawings, where an embodiment of a utility model is shown by way of illustration: FIG. 1 is a partial longitudinal section of the gas generator of the CCD on the input device; FIG. 2 — truss geometry — view A in FIG. one; BB cut in view A.

The input device (Fig. 1) contains a radial inlet element having opposite walls 1 and 2, forming an annular channel 3. The design of the input device is assembly, which allows the mechanical treatment of the inner surface of the walls. Mechanical treatment of the inner surface of the wall 1 forming the air path is performed with a permissible deviation from the theoretically specified value of no more than 0.02 mm.

On the periphery of the walls are rigid connecting elements in the form of a truss 4 (Fig. 1, Fig. 2). The truss is made uniform around the circumference, the truss type of the truss is made triangular, the trusses of the truss 4 have a streamlined profile (Fig. 3). In a specific example of execution, the angle between braces can be made α = 60 °, the brace width b = 8 mm, the maximum brace thickness Cmax = 20 mm.

To the ends of the walls 1 and 2 (Fig. 1) with the help of brackets attached protective grid 5, covering the radial entrance.

In the inlet device, a change in the direction of air flow from the radial inlet to the engine on the axial inlet to the compressor of the gas generator takes place. Air from the atmosphere through the hatch located on the fuselage, enters the engine compartment and further into the input device (Fig. 1). The air passes through the protective grid 5 and enters the annular channel 3, where the air flow changes from radial to axial.

The utility model is designed for the construction of a turboprop engine with a free turbine, intended for use as part of the power plant of light aircraft, but can be used in other designs of compressors. The use of a utility model in the design of input devices allows to reduce disturbing factors in the boundary layer of the air channel and, thereby, to reduce the uneven air flow at the compressor inlet.

Claims (5)

1. An inlet device of a centrifugal compressor containing a radial inlet element having opposite walls forming an annular channel shaped in such a way that the radial air flow is directed axially, rigid connecting elements are located between the walls, a protective grid is installed on the periphery of the walls covering the radial inlet element, characterized in that the connecting elements are made in the form of a truss located on the periphery of the walls, and the truss is made in the form of a triangle The grille, whose braces have a streamlined profile and are evenly distributed around the perimeter of the annular channel, and the shape of the protective grid has a U-shaped profile, in addition, the inner surface of the wall forming the air path is not more than 0.02 from the theoretically specified value mm 2. The input device according to Claim. 1, characterized in that the angle between the braces of the triangular lattice has the value α = 50-60 °, and the ratio of the width of the diagonal bars to their maximum thickness matters

where b is the width of the diagonals, mm; Cmax - diagonal thickness at the maximum, mm.

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