RU2725034C1 - Device for air cleaning from foreign objects in compressor of double-flow turbojet engine - Google Patents

Abstract

FIELD: machine building.SUBSTANCE: disclosed is a device for cleaning air from foreign objects in a compressor of a double-flow turbojet engine. Device prevents passage of foreign objects to the high-pressure compressor stages due to their separation in the fan and support stages of the low pressure compressor. Removal of separated foreign objects is proposed to be performed in the last support step in the form of spatial annular branch in external wall of flow channel of discharge level in zone of axial clearance between rims of impeller and straightening device of stage. Said diversion pipe can simultaneously be used for air bypass and bleeding to engine and aircraft systems. If necessary, it is possible to increase degree of air cleaning from foreign objects due to inclusion of high pressure compressor into the device for cleaning of the first stages with removal of separated foreign objects in one of medium stages of high pressure compressor having air discharge for needs of engine and aircraft systems.EFFECT: proposed device allows preventing ingress of foreign objects to axial steps of high pressure compressor, which improves engine reliability during operation of aircraft from ground, ice and snow-covered aerodromes.1 cl, 4 dwg

Description

The invention relates to the field of aircraft engine manufacturing, specifically to dual-circuit turbojet engines (turbojet engines) (Accepted abbreviations are explained in the text, also on page 8 a complete list of abbreviations is given.) With a fan stage at the inlet. Currently, this type of engine is widely used in civil and military aircraft. In addition, the invention can be applied to ground-based gas turbine units (GTU), where it is also often necessary to protect the engine from foreign objects entering its air-gas path (GWT).

A feature of the layout of many modern aircraft is the low (close to the surface of the earth) engine location under the wing of the aircraft (LA), which leads to the ingress of foreign objects (GV) engines into the GWT, resulting in engine failure due to the destruction of compressor blades.

As a result, the reliability of the engines, flight safety, combat readiness, mobility and regularity of departures are reduced, cases of early removal of engines due to the occurrence of damage to the compressor blades that are unavoidable during operation are frequent.

In addition, indicators of operational manufacturability are significantly deteriorating - the volume of maintenance work (MOT) of engines, aircraft downtime (AT), and the cost of operating AT are increasing.

In the practice of aircraft engine construction, there are known design solutions aimed at reducing the number of hits of PP in the internal circuit of a turbofan engine. Usually, the inertial separation of PP is used for this purpose when they interact with the fan blades and the axial compressor, while some of the PP moving along the central fan zone of the fan moves to the periphery of the internal circuit channel and is discharged into the external motor circuit along the axial clearance between the impeller rims RK fan and input guide vane (VNA) of the internal circuit. The other part of the PP remaining in the internal circuit is separated by a group of subsequent retaining stages of the low pressure compressor (LPC), moves to the periphery of the flow channel, and after the last stage it is discharged into the bypass and air intake channel into the external circuit or into the surrounding air space. The described constructive solution is used in different types of foreign and domestic turbofan engines and in land gas turbine engines [1, 2, 3]; it allows one to significantly reduce the number of SPs entering the GWT engines. However, the task of reducing the number of PP hits in the internal path of the turbofan engine has not been completely solved and remains relevant at present for many types of engines.

One of the significant reasons for the insufficient purification of the air entering the high-pressure compressor (HPC) of the engine from the PP is the low efficiency of the PP removal process in the last outlet stage of the KND retaining stages group. It is known that in existing air purification devices, the PP removal from the group of retaining steps is performed after the rectifying apparatus (SA), the discharge steps - see [1, 2, 3]. But in this design of the tap, the inertial and separation capabilities of foreign objects that they possess after the end of interaction with the blades of the RK of the tap stage are practically not used. The indicated possibilities are connected with the presence of radial and tangential components in the outgoing PP in the vector, so that the PP can intensively move in the radial direction. But the CA blade (its outer wall) located behind the RC in its immediate vicinity prevents the radial movement of the PP, and moreover, when interacting with the details of the SA, the links are imposed on the PP, under the influence of which the radial component of the PP velocity changes its direction and transforms from centrifugal to centripetal.

In addition, the tangential (circumferential) component of the speed of objects changes its value to virtually zero level, since when interacting with SA blades, the PPs acquire a direction of motion lying in the meridional plane of the step. In this case, the axial component of the speed of the PP increases. As a result, leaving the crown SA PP no longer have high separation capabilities, do not have time to get into the receiving hole for the separated objects located after the SA, and remain within the flow channel. Further, the SPs enter the subsequent stages of the HPC, which have a higher level of peripheral speed, and the group of the last steps with small-sized blades, on which the SP is manifested with particular intensity. The described problem is more or less characteristic of all the above devices - analogues [1, 2, 3]. By the totality of the features of the claimed device, coinciding with the features of the device - analogue, as a prototype of the present invention adopted domestic serially-produced turbojet type PS-90A [1]. This engine is used on several types of domestic aircraft and for it the solution to the problem of reducing the number of hits of PP in the internal circuit of the engine’s GW is very important.

The technical problem that is solved by the present invention is to increase the reliability of the turbofan engine, improve its operational manufacturability, reduce the cost of engine maintenance by improving the cleaning of PP air entering the HPC.

The essence of the invention lies in the fact that in the last axial stage of the group of retaining stages of the low pressure switch, in which the separated PP is withdrawn and removed from the compressor flow path, the tap is made in the axial clearance section between the RC and the CA stage.

In the indicated section between the RC and the SA along the outer contour of the flow channel, a receiving annular hole is made located along the entire circular perimeter of the flow channel. The width of the indicated receiving hole from the output frontal plane of the stage RK to the entrance to the CA of the foot is made taking into account the passage through the receiving hole of the largest possible part of the PP moving from the flow channel to the outer space of the outlet ring channel. This outlet channel is formed between the outer wall of the flow channel of the stage and the outer shell CA. Through the receiving ring hole and the exhaust ring channel of the PP, separated to the periphery of the flow channel, together with some part of the air, they are removed from the flow channel of the stage and then sent either to the external circuit of the engine or to the air consumer, if necessary, the air can be pre-cleaned from the PP.

The proposed embodiment of the discharge of the PP in the discharge stage provides a significant improvement in the efficiency of the process of removal of objects from the flow channel, since in this version of the discharge stage the main reasons that impede the effective removal of the PP (- the location of the CA ring in the immediate vicinity of the exit from the RK) are eliminated, and created conditions for unobstructed access of PP with high separation potential to the outlet channel.

If the turbofan engine is operated on aircraft from aerodromes that are highly contaminated with hazardous airplanes (soil, ice, snowy), which leads to an increased frequency of nicks on the blades of high pressure engines, including at the last small stages of high pressure engines, the proposed device provides an option for increasing the efficiency of cleaning the air entering the last stages of the HPC, due to the inclusion of an additional cleaning stage from the first few axial stages of the HPH with the removal of the separated PP in the middle stage of the HPH. In this case, the PP removal from the flow channel of the KVD exhaust stage is performed in the same way as in the retaining stage of the KND.

In FIG. 1 shows a longitudinal section of a turbofan engine compressor and a device for purifying air from PP;

In FIG. 2 - a longitudinal section of the low pressure valve (fan and retaining stages) in an enlarged view;

In FIG. 3 - a longitudinal section of the exhaust stage of the HPC, in which the PP is removed and the air is taken from the compressor for the needs of the engine and aircraft systems - place I of FIG. 1, in an enlarged view;

In FIG. 4 is a fragment of the cross-section of the flow path into the outlet stage of the group of first stages of HPC, the path of the PP is a view along arrow B of FIG. 1.

A device for air purification from PP in the turbofan compressor is included in the compressor - 1 FIG. 1 and includes KND - 2. In addition, a part of the KVD - 3 stages can also be included in the device. The connection of the KND and KVD modules is carried out using an intermediate case - 2.

The KND includes a fan stage - 4, consisting of a PK with blades - 7 of FIG. 1, 2 and two crowns CA - BHA of the internal circuit with blades 10 and CA of the external circuit with blades - 10 ', as well as a group of retaining steps - 5, which includes several axial steps, of which the last with working blades - 12 and CA with blades - 14 is a discharge stage.

размером по сравнению с типовыми размерами указанного зазора, с целью получения лучшей эффективности удаления ПП из отводящей ступени.Between the crowns of the Republic of Kazakhstan and CA, an axial clearance of 13 is provided, which is made with

size compared with the typical dimensions of the specified gap, in order to obtain better removal efficiency of PP from the discharge stage.

Within the width of the axial clearance - 13 between the RC and the front edge - 18 of the outer shell - 17 of the straightening device along the outer contour of the flow channel of the stage, a receiving ring hole is made - 15 '' located along the entire circular perimeter of the flow channel and communicating the internal space of the flow channel - 13 `` steps with external space - 16 ''. The width of the receiving hole is 15 '' from the rear frontal plane of the stage RK to the leading edge 18 of the outer shell - 17 CA (in this case, the shell acts as a flow separator), taking into account the passage through the specified receiving hole of the largest possible part of the PP moving from the flow channel - 13 '' to the external (peripheral) space - 16 ''.

Within the axial clearance - 13, the space of the flow channel - 13 '' steps and the external space - 16 '' are limited from the outside by the wall - 16, which passes with a gap of 19 from the shell - 17 CA, forming with it an outlet ring channel - 20.

The input part of the specified channel is the receiving hole - 15 '' and the external space - 16 ''.

In addition to KND, the front steps - 3 ', FIG. 1 included in the KVD-3.

части ПП, движущихся из проточного канала 13''' к внешнему пространству - 16'''.Behind the indicated steps, there is an intermediate stage of the HPC, in which air is taken (bypassed) from the HPC. This stage place I of FIG. 1 is also included in the cleaning device as a discharge stage. In the specified outlet stage, the same constituent elements are present as in the outlet stage of the low pressure switch. The numbering of the elements in FIG. 3 also saved with the addition of a stroke. Between the crowns of the Republic of Kazakhstan with blades - 12 'Fig. 3 and CA with vanes - 14 ', an axial clearance of 13' is provided. On the outer shell of the stage SA from the input side, a separator is made - 17 'with a leading edge - 18'. Across the width of the axial clearance 13 'between the RK of the step and the leading edge 18' along the outer contour of the flow channel - 13 '''of the step, a receiving annular hole is made 15''' located along the entire circular perimeter of the flow channel and communicating the internal space of the flow channel 13 '''with external (peripheral) space 16'''. The width of the receiving hole - 15 '''from the rear frontal plane of the stage RK to the leading edge - 18' of the separator - 17 'is made taking into account the passage through the specified receiving hole is possible

parts of the PP moving from the flow channel 13 ″ to the external space - 16 ″.

Within the width of the axial clearance - 13 ', the space of the flow channel - 13' '' and the external space - 16 '' 'are limited externally by the external wall - 16', which passes with a gap of 19 'from the separator - 17', forming with it an outlet ring the channel is 20 '. The input part of the specified channel is the receiving hole - 15 '' 'and the external space - 16' ''. The withdrawal annular channel - 20 'communicates with the collection cavity 21' and serves to output the separated PP from the discharge stage.

During the operation of the turbofan engine in the airspace containing the airflow, the air together with the airflow enters from the airplane air intake into the inlet channel - 6 of FIG. 1 engine. Having passed through the interscapular channels of the rotor blades - 7 of the fan, the air flow is divided into two parts: the central (plenum) part of the flow enters the internal circuit - 8 of FIG. 1, 2, the external part - into the external circuit - 9. Separation of the flow along the circuits is carried out by a separator, the role of which is played by the outer shell 11 of the input guide apparatus (VNA) of the internal circuit - 8. In the internal circuit, air enters the VNA blade ring with blades 10, and in the external circuit, in the external circuit SA with blades 10 'of FIG. 1, 2. In FIG. Figure 2 shows how the air entering the inner circuit passes through the fan zone of the fan blade feather - 7, conventionally indicated by sections aa, bc, cc. The paths of the PP entering the internal circuit are shown by dashed lines. When interacting with rotating fan blades, a part of the PP moves in the radial direction and exits along the annular gap 8 'between the blades - 7 RK and the leading edge - 11' of the outer shell - 11 VNA from the inner loop - 8 to the outer - 9. Basically this is a PP, moving from the peripheral zone (between sections bc and cc) - along the trajectories - 22.

The other part of the PPs that entered the near-ceiling zone in the region of sections aa and bc, for the most part, do not have time to move in the radial direction to a gap of 8 and go into the outer loop, remain in the flow channel of the inner loop, move along trajectories 23 and they reach the peripheral zone of the flow channel in the retaining steps of the CPV. In the discharge stage under the influence of the blades - 12 RK PP receive the corresponding impulse and the output velocity vector having radial and circumferential components.

Moving by inertia in the space of axial clearance - 13, free from obstacles, in the radially tangential-axial direction, the PPs move from the peripheral zone of the flow channel - 13 '' to the inlet - 15 '', pass through it and fall into the outer space 16 '', which is the input section of the outlet ring channel 20. Next, the PPs enter the collection and distribution cavity - 21 and are sent for discharge into the external circuit of the engine, or together with the air, to the consumer. If necessary, the air is preliminarily purified from the separated PP contained in it.

Despite the fact that when passing through the LPC, the bulk of the PP is removed from the air flow going to the HPC, it remains some of the PP that are not removed, they follow the trajectories - 24 of FIG. 1 and go to the steps of the KVD. When the engine is used under normal conditions, these PPs are no longer so dangerous for HPC blades (smaller fractions, fewer), which meets the requirements for the reliability and operational manufacturability of the engine.

But with the regular operation of the turbofan engine in conditions of increased air pollution, the passage of even a small percentage of the amount of PP may be unacceptable.

In the present invention, it is possible to improve the efficiency of cleaning the air going to the last stages of the HPC, by forming in the device an additional stage of air purification in the HPC, repeating the work of air purification in the supporting steps of the CPV.

Foreign objects passing to the HPC and moving along the trajectories - 24 fig. 1, 2, 3, fit to the blades - 12 'of the PK of FIG. 3 of the exhaust stage of the HPC, they acquire from the working blade an output velocity vector having axial, radial, and circumferential components. Moving by inertia in the space of the axial clearance - 13 ', the PPs move from the peripheral zone of the flow channel - 13' '' to the inlet - 15 '' ', pass through it and fall into the outer space 16' '', which is the input section of the outlet annular channel 20'. Next, the PP enter the collection and distribution cavity 21 ', and are sent through the pipe - 25 of FIG. 1 to be emitted to the external circuit of the engine or together with air to its consumer. In FIG. 4 shows the trajectory - 24 of the PP movement after the end of the movement of the object together with the working blade 12 '- view along arrow B of FIG. 3. The subject freely moves in a radially circumferential direction in the space of the flow channel 13 ″ of the stage, reaches the radial distance of the front edge 18 ′ of the separator 17 ′ - R per. cr 18 ', passes through the receiving annular hole 15' '', collides (or does not collide) with the conical surface of the separator 17 and then follows the outlet ring channel 20 - FIG. 3 into the receiving and dispensing cavity 21 ', from where the pipe - 25 of FIG. 1 is output to the discharge line.

Sources of information.

1. A.A. Inozemtsev et al. “PS-90A Aircraft Engine” Moscow, Libra-K, 2007

2. RU patent No. 2198311 01/03/2001, F02C 7/052 Gas turbine installation

3. US patent No. 5123240 June 23, 1992, F02G 3/00 Method and device for removing foreign objects from the internal circuit of a gas turbine engine.

List of accepted abbreviations

AT - aeronautical engineering;

VNA - input guide vane;

GWT - gas-air duct;

GTU - gas turbine installation;

KVD - high pressure compressor;

KND - low pressure compressor;

LA - aircraft;

PP - foreign objects;

RK - impeller;

CA - straightening apparatus;

TO - maintenance;

Turbofan engine - dual-circuit turbojet engine.

Claims (2)

1. A device for cleaning air from foreign objects in the compressor of a dual-circuit turbojet engine, consisting of a fan stage and retaining stages of a low pressure compressor, as well as stages of a high pressure compressor, based on the principle of inertial separation of foreign objects when they interact with the compressor blades and moving objects from the compressor flow channel to the peripheral zone of the channel, which includes a fan stage and a group of retaining stages of the low pressure compressor, in which the last stage of the group discharged foreign objects separated from the air flow, characterized in that the removal of foreign objects from the flow channel of the exhaust stage a section of the axial clearance between the impeller and the straightening device of the stage, on the portion of the specified axial clearance between the impeller and the straightening device along the outer contour of the flow channel of the stage, a receiving annular hole is made A hole located along the entire outer circumferential perimeter of the flow channel of the stage and communicating the internal space of the flow channel with the external space of the outlet channel, wherein the width of said receiving annular hole from the output frontal plane of the stage impeller to the leading edge located on the outer rim of the stage straightening apparatus is made taking into account the passage through the receiving annular hole is possible

part of foreign objects moving from the flow channel to the outer space of the outlet channel, also on the specified section of the axial clearance, the outer wall of the flow channel of the stage is located on

the distance from the axis of the stage compared with the outer diameter of the entrance to the straightening apparatus of the stage and its outer shell, and forming, together with the specified outer shell, a diverting annular channel intended for removing foreign objects from the diverting stage. 2. A device for cleaning air from foreign objects in the compressor of a dual-circuit turbojet engine according to claim 1, wherein the air cleaning device further includes a group of several first stages of the high pressure compressor, the last of which, which is a discharge stage, remove foreign objects from the flow channel of the stage, it is made similar to the outlet described in paragraph 1, and can be combined with the selection of air from the stage for the needs of the engine and aircraft systems.

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