EP0589745B1 - Inlet control system of a turbomachine - Google Patents

Description

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

The invention relates in particular to a system of setting for a compressor air intake system centrifugal, and more particularly of the centrifugal compressor external from 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 the compressors, and which allows these suction machines directly, or through a plenum, ambient air to properly feed their part axial input.

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

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

In one of these extreme stall positions, called fully open position, all vanes are oriented substantially radially.

In the other extreme setting position, called fully closed position, all blades are oriented tangentially to the annular entry gases.

By modifying the angular setting of the blades, it is possible to fine-tune the compressor supply conditions and therefore adapt the flow rate and the pressure level supplied to the different circuits powered by this compressor.

In particular, and in the case of closure complete, the adjustment system allows to reduce significantly the flow through the compressor and therefore the power needed to train it. Such an adaptation is necessary during the phases of starting certain rotary compressor machines external or auxiliary.

In conventional adaptation devices of the type described above and for a determined range of angular setting of the blades, these impose on the flow gaseous gyratory flow towards the entrance compressor. This operation is sought for satisfy some impact on the vanes compressor. For certain operating modes, and in the case of the fully closed position, it may overheat indoors compressor resulting from 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 realize control means of the adjustment in which a blade actuating cylinder ensures very little play between the blades, in the position of closing, in order to maintain a minimum gas flow at through the compressor and to prevent it from overheating.

However, the control means and the cylinder actuation then have a complex structure and expensive.

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

We also know by documents FR-A-2 294,345 (United Turbine, on which the preamble of claim 1 is based), FR-A- 2,438,156 (Alsthom Atlantic), FR-A- 2 139 741 (SNECMA), DE-A- 3 717 590 (Teledyne Industries) and BE-A-672 432 (Davidson & Co), various vane compressor systems, in which the blades are either devoid of communication between the lower and upper surfaces, either with a communication of very small section and whose position, the configuration neither allow nor limit compressor heating, or inspect the interior of the compressor by an endoscopy technique.

The object of the invention is to propose a system for setting of the type mentioned above which allows simultaneously remedy the disadvantages that come to be mentioned.

As claimed, the system of the invention allows the adjustment of the air supply conditions of a turbomachine of the type comprising a series of guide vanes mounted movable between an open position and a closed position of a pipe air inlet of the turbomachine. At least one of the guide vanes has an orifice opening onto the profiled body of the blade. Said blades are arranged in a crown, and each blade is pivotally mounted around an axis parallel to the axis of the crown. According to the invention, said opening orifice crosses the body of the blade and is arranged under the shape of a slit extending in the middle part of the blade substantially in the longitudinal direction of the gas flow the along the dawn, so as to connect the lower surface and the dawn surface and to create a secondary air flow capable of avoiding excessive heating of the turbomachine compressor and allowing endoscopic inspection of the blades.

• l'orifice est agencé dans la partie centrale de l'aube ;
• 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 is arranged in the central part of the blade;
• 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 gas turbine, characterized in that it comprises a compressor external centrifugal load with which the air intake system is fitted 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 accompanying drawings in which :

FIG. 1 represents a diagram of an auxiliary group of gas turbine power with an external compressor of load can be fitted 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 of a system according to the invention.

Figure 3 is a half sectional view of a charge compressor air inlet line shown in Figure 2.

Figure 4 is a half cross-sectional view of the annular line of the charge compressor, according to the line 4-4 of figure 3, and in which the blades are shown in the open position complete.

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 the corresponding intermediate position to a gyratory flow downstream of these.

Figure 7 is a perspective view of a blade director with a port for communication of its upper surface with its lower surface, corresponding to a mode for carrying out the invention.

The adjustment system according to the invention finds in particular to apply in the case of auxiliary groups gas turbine power, as will be described more in detail later, 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 that turboshaft engines, turbopropellers, turbochargers, auxiliary power units to direct debit, etc.

Of course, this compressor can be of the type axial, radial or mixed. 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 turbine to gas, comprising a charge compressor fitted with a adjustment system according to the invention.

In the embodiment shown in this figure, this set designated by the general reference 1 comprises a turbine engine 2 shown diagrammatically in the area bounded by a dashed line outline.

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 other devices operated by compressed air such as than pneumatic turbine engines or the like.

Turboshaft 2 is also suitable for drive an electric generator 5.

These different organs 2, 3 and 5 are coupled by means of a drive shaft 6 which comprises by example a conventional type reducer (not shown).

When the turbine engine 2 is running, air ambient is sucked in 7 to an inlet of a compressor 8 of the turbine engine. Compressed air from the compressor is mixed with a fuel 9 before being injected into a combustion chamber 10 for continuous burning therein.

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

The rotation of the shaft 6 ensures the training of power compressor 8, charge compressor 3, the electric generator 5 and possibly others accessories.

As can be seen in Figure 2, the compressor has an annular air inlet pipe 14 allowing air to be drawn into a plenum 15 and to power a centrifugal mobile 16.

The centrifugal mobile 16 has a series blades 17 for transforming into pneumatic energy mechanical energy transmitted by the drive shaft 6.

Air leaks at the top of mobile vanes 17 are limited by a static cover 18.

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

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

The radial air flow is then transformed in axial flow to properly power the mobile centrifugal 16. The air 22 is compressed by the blades 17 in rotation and is pushed tangentially across broadcast.

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

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

Means for adjusting feeding conditions are also provided to adjust the air flow and pressure level supplied to the assembly pneumatic 4.

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

As can be seen in Figures 2 to 6, the vanes 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 pitch and are simultaneously orientable through control shafts 26 and a mechanical assembly control aid 28.

By modifying the timing of the blades 24 on demand, you can fine-tune the conditions compressor supply, and therefore adapt the flow and the pressure level supplied to the various components powered by this compressor.

In particular, and in the closed position shown in Figure 5, the adjustment system significantly reduces air flow passing through the compressor and thereby the necessary power to train him through the tree 6 of the turbine engine 2.

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

Finally, when the turbomachine 1 stops, the blades guidelines 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 open position complete, illustrated in Figure 4, to allow endoscopic control of blades 17 and 20 of the compressor charging 3.

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

As illustrated in Figure 7, the orifice 27 can be made in the form of a through slot longitudinal, that is to say which extends in the part median of directing dawn 24 substantially according to the longitudinal direction of gas flow along dawn.

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

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

Furthermore, for stalling positions angular close to the fully open position of the adjustment system, the holes are inoperative because the small pressure difference between the intrados and extrados of guide vanes.

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

The endoscopic inspection is very simple, in the fully closed position, by inserting the endoscope through an orifice 27.

Finally, for certain operating regimes of the turbomachine corresponding to specific ranges of gas flow rate and angle, flow gyratory imposed on the gas flow downstream of the blades guidelines 24 may cause unwanted aerodynamic noise due to noise disturbance caused to the environment immediate, due to the corresponding energy loss inside the annular pipe and because of the risks of vibratory excitation of mechanical parts arranged near this pipe.

The presence of orifices in the blades allows, in accordance with the teachings of document DE-A-2.227.460, obtain attenuation or suppression of this noise undesirable.

Claims (7)

1. System (23) for control of the conditions of the supply of air to a turbomachine of the type comprising a series of guide vanes (24) mounted so that they can move between a position in which an air inlet duct (14) of the turbomachine is open and a position in which it is closed, in which at least one of the guide vanes (24) comprises an orifice (27) which opens onto the profiled body of the vane, said vanes (24) being arranged in a ring, and each vane being mounted so that it can pivot about a pin (26) parallel to the axis of the ring, characterized in that the said open orifice (27) passes through the body of the vane and is designed in the form of a slot extending into the middle part of the vane (24) more or less in the longitudinal direction of gaseous flow along the vane, so as to place the pressure face and the suction face of the vane (24) in communication and so as to create a secondary air flow capable of avoiding excessive heating of the compressor of the turbomachine and of allowing the blading to be inspected endoscopically.
2. Control system according to Claim 1, characterized in that an open orifice (27) is made in just one guide vane (24) so as to attenuate the aerodynamic noise due to vibrational phenomena.
3. Control system according to Claim 1, characterized in that open orifices (27) are made in two diametrically opposed guide vanes (24) so as to attenuate the aerodynamic noise due to vibrational phenomena.
4. Control system according to Claim 1, characterized in that open orifices (27) are made in three guide vanes (24) situated 120° apart so as to attenuate the aerodynamic noise due to vibrational phenomena.
5. Control system according to Claim 1, characterized in that in the closed position, the trailing edge and the leading edge of two consecutive vanes (24) are adjacent, because the vanes (24) are contiguous.
6. Centrifugal compressor, characterized in that it comprises an air intake system equipped with a control system produced according to any one of the preceding claims.
7. Gas turbine auxiliary power unit, characterized in that it comprises an external charging centrifugal compressor produced in accordance with Claim 6.

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