EP0589745A1 - Inlet control system of a turbomachine - Google Patents

Abstract

The invention proposes a control (regulating) system (23) making it possible to master the heating of the gases downstream of the control system, to attenuate the aerodynamic noise generated by the gyratory flow downstream of the guide vanes (24) of the control system and to facilitate endoscopic checking of the blading of a compressor (3) by virtue of emerging orifices (27) formed in the control system (23) and particularly through at least one guide vane (24). The invention finds particular application in the production of a control system equipping an air intake system of an external centrifugal compressor of an auxiliary gas turbine power unit. <IMAGE>

Description

The present invention relates to a system for adjusting the air supply conditions of a turbomachine.

The invention relates in particular to an adjustment system for an air intake system of a centrifugal compressor, and more particularly of the external centrifugal compressor of an auxiliary power unit to a gas turbine.

The invention is more particularly applicable in the case of an annular pipe generally used in turbomachinery, and in particular in the suction part of compressors, and which allows these machines to suck directly, or through a plenum, the ambient air to properly supply their axial inlet part.

In the radial part of the gas inlet pipe, means for adjusting the supply conditions of the tubomachine, such as guide vanes, are arranged around the axis of the machine and at regular intervals over a given diameter. .

These blades, arranged in a crown, are generally of variable angular setting and they can be oriented simultaneously between two extreme positions.

In one of these extreme setting positions, called the fully open position, all the blades are oriented substantially radially.

In the other extreme setting position, called the fully closed position, all the blades are oriented tangentially with respect to the annular gas inlet.

By modifying the angular setting of the blades on demand, it is possible to precisely adjust the supply conditions of the compressor and therefore to adapt the flow rate and the pressure level supplied to the various circuits supplied by this compressor.

In particular, and in the case of complete closure, the adjustment system makes it possible to significantly reduce the flow rate which passes through the compressor and therefore the power required to drive it.

Such an adaptation is necessary during the start-up phases of certain rotary machines with external or auxiliary compressor.

In conventional adaptation devices of the type described above, and for a determined range of angular setting of the blades, they impose on the gas flow a gyratory flow in the direction of the inlet of the compressor. This operation is sought to satisfy a certain incidence on the moving blades of the compressor.

For certain operating modes, and in the case of the fully closed position, excessive heating may occur inside the compressor which results from the insufficient gas flow which then passes through the turbomachine. This heating can be detrimental to the mechanical strength of the assembly.

In order to remedy this drawback, it has already been proposed to produce means for controlling the adjustment system in which a blade actuating cylinder ensures very little clearance between the blades, in the closed position, in order to maintain a flow rate. minimum gaseous flow through the compressor and to prevent it from overheating.

However, the control means and the actuating cylinder are then of a complex and costly structure.

In addition, when the turbomachine is stopped, the guide vanes are in the fully closed, or almost complete, position and it is necessary to partially disassemble the air intake device to perform an endoscopic inspection of certain organs of the group. auxiliary power, and for example compressor blades. This inspection also requires the ability to control, when the turbomachine is stopped, the adjustment system, in order to bring the blades into their so-called fully open position.

The object of the invention is to propose an adjustment system of the type mentioned above which makes it possible to simultaneously remedy the drawbacks which have just been mentioned.

To this end, the invention provides an adjustment system comprising a series of guide vanes mounted movable between an open position and a closed position of an air inlet pipe of the turbomachine, characterized in that at least one of the blades has a through hole which passes through the profiled body of the blade.

• l'orifice met en communication l'intrados et l'extrados de l'aube;
• l'orifice est agencé dans la partie centrale de l'aube;
• l'orifice se présente sous la forme d'une fente qui s'étend sensiblement selon la direction de l'écoulement gazeux le long de l'aube;
• les aubes sont agencées en couronne et chaque aube est montée pivotante autour d'un axe parallèle à l'axe de la couronne;
• en position de fermeture, le bord de fuite et le bord d'attaque de deux aubes consécutives sont sensiblement adjacents, les aubes étant jointives.

According to other characteristics and advantages of the invention:

• the orifice connects the intrados and extrados of dawn;
• the orifice is arranged in the central part of the blade;
• the orifice is in the form of a slot which extends substantially in the direction of the gas flow along the blade;
• the blades are arranged in a crown and each blade is pivotally mounted about an axis parallel to the axis of the crown;
• in the closed position, the trailing edge and the leading edge of two consecutive blades are substantially adjacent, the blades being contiguous.

The invention also provides a centrifugal compressor characterized in that it comprises an air intake system produced in accordance with the teachings of the invention.

The invention also provides an auxiliary power unit with a gas turbine, characterized in that it comprises an external centrifugal load compressor whose air intake system is equipped with an adjustment system produced in accordance with the teachings of the 'invention.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

FIG. 1 represents a diagram of an auxiliary power unit with a gas turbine comprising an external charge compressor which can be equipped with an adjustment system according to the invention.

Figure 2 is a half sectional view of a charge compressor of an auxiliary power unit equivalent to that shown in Figure 1 and equipped with a system according to the invention.

FIG. 3 is a half-view in section of an air inlet pipe of the charge compressor illustrated in FIG. 2.

Figure 4 is a half cross-sectional view of the annular duct of the charge compressor, along line 4-4 of Figure 3, and in which the guide vanes are shown in the fully open position.

Figure 5 is a view similar to that of Figure 4, but in which the guide vanes are shown in the fully closed position.

Figure 6 is a view similar to those of Figures 4 and 5, but in which the guide vanes are shown in an intermediate position corresponding to a gyratory flow downstream thereof.

Figure 7 is a perspective view of a guide vane having an orifice for communicating its upper surface with its lower surface, corresponding to an embodiment of the invention.

The adjustment system according to the invention finds particular application in the case of auxiliary power units with gas turbine, as will be described in more detail below, but of course, they can be used in other turbomachinery or industrial devices having for example a compressor with one or more stages, fitted with variable-pitch guide vanes, such as turboshaft engines, turbopropellers, turbochargers, auxiliary power units with bleed power, etc.

Of course, this compressor can be of the axial, radial or mixed type. Likewise, the air inlet can be radial, axial or mixed.

In Figure 1, there is shown by way of example a diagram of an auxiliary power unit with a gas turbine, comprising a charge compressor equipped with an adjustment system according to the invention.

In the embodiment shown in this figure, this assembly designated by the general reference 1 comprises a turboshaft engine 2 shown diagrammatically in the area delimited by a contour in phantom.

This turbine engine 2 is used to drive a charge compressor 3 supplying compressed air to an accessory pneumatic assembly, such as for example an air conditioning system 4 of an airplane or to other devices actuated by compressed air such as pneumatic turbine engines or the like.

The turbine engine 2 is also suitable for driving an electric generator 5.

These different members 2, 3 and 5 are coupled by means of a drive shaft 6 which comprises, for example, a reduction gear of the conventional type (not shown).

When the turbine engine 2 is operating, ambient air is sucked at 7 to an inlet of a compressor 8 of the turbine engine. The compressed air leaving the compressor is mixed with a fuel 9 before being injected into a combustion chamber 10 to burn there continuously.

The burnt gases 11 are expanded in a two-stage axial turbine 12 to supply the desired power to the drive shaft 6, before being ejected into the atmosphere through an exhaust nozzle 13 disposed downstream of the turbine.

The rotation of the shaft 6 drives the power compressor 8, the charge compressor 3, the electric generator 5 and possibly other accessories.

As can be seen in FIG. 2, the compressor has an annular air inlet pipe 14 making it possible to draw air into a plenum 15 and to feed a centrifugal mobile 16.

The centrifugal mobile 16 comprises a series of blades 17 making it possible to transform the mechanical energy transmitted by the drive shaft 6 into pneumatic energy.

Air leaks at the top of the movable blades 17 are limited by a static cover 18.

The charge compressor also comprises a diffusion assembly consisting of a diffuser 19, a radial diffuser with blades 20 and a volute 21 which is intended to supply compressed air to the pneumatic assembly 4 mentioned above.

When the charge compressor 3 is operating, the ambient air, designated by the general reference 22 in FIG. 2, is drawn into the supply plenum 15 over the entire periphery of the air inlet.

The radial flow of the air is then transformed into an axial flow in order to supply the centrifugal mobile 16 suitably. The air 22 is compressed by the blades 17 in rotation and is delivered tangentially into the diffusion assembly.

The kinetic energy of the air leaving the mobile 16 is then transformed into pressure in the smooth diffuser 19 and in the radial diffuser with blades 20.

At the outlet of the diffusion assembly, the air is collected in the volute 21 to be sent to the pneumatic assembly 4.

Means for adjusting the supply conditions of the compressor are also provided for adjusting the air flow rate and the pressure level supplied to the pneumatic assembly 4.

These means consist of an adjustment system designated by the general reference 23 in FIG. 2, which comprises a series of guide vanes 24 arranged in the radial part of the annular air inlet pipe 14.

As can be seen in Figures 2 to 6, the blades 24 are arranged in a crown on the radial part of the gas inlet, at regular intervals, on a control diameter centered on the axis 25 of the machine.

The vanes 24 are of variable setting and can be oriented simultaneously by means of control shafts 26 and an auxiliary mechanical control assembly 28.

By modifying the timing of the blades 24 on demand, the conditions can be precisely adjusted. compressor power supply, and therefore adapt the flow rate and the pressure level supplied to the various components supplied by this compressor.

In particular, and in the fully closed position illustrated in FIG. 5, the adjustment system makes it possible to significantly reduce the air flow passing through the compressor and therefore the power necessary to drive it through the shaft 6 of the turbine engine 2.

In the case of the fully closed position illustrated in FIG. 5, excessive heating may occur downstream of the guide vanes 24 which is detrimental to the mechanical strength of the compressor assembly, and in particular to the strength of the centrifugal mobile 16, the radial diffuser 20 and / or the volute 21.

Finally, when the turbomachine 1 stops, the guide vanes 24 are in the fully closed position and it is then necessary to dismantle the control system 28 to return the guide vanes to the fully open position, illustrated in FIG. 4 , in order to allow endoscopic control of the blades 17 and 20 of the charge compressor 3.

According to the invention, at least one blade 24 has an orifice 27 for communicating its upper surface with its lower surface.

As illustrated in FIG. 7, the orifice 27 can be produced in the form of a longitudinal through slot, that is to say which extends in the middle part of the guide vane 24 substantially along the longitudinal direction of gas flow along the blade.

Ports 27 for communication can be provided in all of the guide vanes, in a single vane, in two diametrically opposite vanes, in three vanes arranged at 120 ° relative to each other, or in any other configuration of blades.

Of course, the choice of this configuration, the shape, the size and the position of the orifices in the blades make it possible to optimize the different parameters of operation of the adjustment system according to the invention.

Furthermore, for angular setting positions close to the fully open position of the adjustment system, the orifices are inoperative due to the small pressure difference existing between the lower and upper surfaces of the guide vanes.

The adjustment system according to the invention is particularly simple to carry out insofar as it requires no additional mechanical member and it also allows a slight reduction in the mass of the system.

The endoscopic inspection is carried out very simply, in the fully closed position, by introducing the endoscope through an orifice 27.

Finally, for certain operating regimes of the turbomachine corresponding to determined ranges of flow rate and angle of flow of the gas flow, the gyratory movement imposed on the gas flow downstream of the guide vanes 24 can cause undesirable aerodynamic noise because noise annoyance caused to the immediate environment, due to the corresponding loss of energy inside the annular pipe and due to the risks of vibratory excitation of the mechanical parts placed near this pipe.

The presence of orifices in the blades makes it possible, in accordance with the teachings of document DE-A-2,227,460, to obtain an attenuation or a suppression of this undesirable noise.

Claims (9)

System (23) for adjusting the air supply conditions of a turbomachine of the type comprising a series of guide vanes (24) mounted movable between an open position and a closed position of an inlet pipe d 'air (14) of the turbomachine, characterized in that it comprises means for creating a secondary gas flow through the adjustment system. Adjustment system according to claim 1, characterized in that at least one of the guide vanes (24) has a through hole (27) which passes through the profiled body of the vane. Adjustment system according to claim 2, characterized in that the orifice (27) communicates the lower surface and upper surface of the blade (24). Adjustment system according to claim 3, characterized in that the orifice is arranged in the central part of the blade (24). Adjustment system according to claim 4, characterized in that the orifice (27) is in the form of a slot which extends substantially in the direction of the gas flow. Adjustment system according to any one of the preceding claims, characterized in that the blades (24) are arranged in a crown and in that each blade is pivotally mounted about an axis (26) parallel to the axis of the crown . Adjustment system according to claim 6, characterized in that, in the closed position, the trailing edge and the leading edge of two consecutive blades (24) are adjacent, the blades (24) being contiguous. Centrifugal compressor, characterized in that it comprises an air intake system equipped with an adjustment system produced according to any one of the preceding claims. Auxiliary power unit with gas turbine, characterized in that it comprises an external centrifugal load compressor produced in accordance with claim 8.

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