FR3042820A1 - DEVICE FOR VENTILATION OF A TURBOMACHINE COMPARTMENT - Google Patents

Abstract

Ventilation device (40, 40 ') of a turbomachine compartment, in particular an aircraft turbomachine, having an air inlet (41, 41') connected to a diffuser (44, 44 '), characterized in that it further comprises a body (46, 46 ') located downstream of the diffuser, the diffuser (44, 44') and the body (46, 46 ') defining between them an air passage section, one (46, 44 ') of said diffuser and said body being movable relative to the other (44, 46') so as to modify said section, the body (44, 44 ') being further configured to deflect foreign objects likely to cross the section.

Description

Ventilation device of a turbomachine compartment

TECHNICAL FIELD The invention relates to a device for ventilating a turbomachine compartment such as an aircraft turboprop engine.

STATE OF THE ART

In all engine applications (turbofan, turboprop, etc.), the bucket compartment houses a number of sensitive equipment that may rise in temperature during a flight. This is particularly the case of the FADEC calculator.

A ventilation of the nacelle compartment is therefore necessary. For this, a sample is usually made via a scoop located on an outer wall of the nacelle and capturing ambient air.

Depending on the phase of flight, the feeding conditions of the scoop can vary very strongly. In the case of a turboprop, two phases can be distinguished in particular: - in cruising: the total available pressure upstream is high (speed of advance of the aircraft) and the static pressure downstream of the system (confluence with the exhaust) is low (operating point adapted), which results in a ventilation flow of the nacelle very important, - at ground idle: the total available pressure upstream is very low (only due to the low compression of the propeller) and the downstream static pressure is relatively high (operating point highly unsuitable), which results in a very low ventilation rate of the nacelle.

The problem of optimizing the ventilation flow of the nacelle must meet two objectives and a constraint.

The first objective is to ensure a minimum flow in order to sufficiently cool the equipment installed in the bucket compartment, which is a critical point at idle ground.

The second objective is to limit the flow rate to a certain maximum flow to ensure the effectiveness of the fire extinguishing system of the bucket compartment, which represents a critical point in flight.

Finally, the constraint is to limit the drag of the system (difference between the trailing drag and the residual thrust recovery in the nozzle). This trail is increasing with the flow through the nacelle. One of the degrees of freedom to adjust the flow in the nacelle is the pressure drop between the catchment area and the exhaust zone. Thus, to minimize the flow rate in the nacelle, it is necessary to increase these pressure losses while to increase the flow rate, they must be minimized.

The satisfaction of the first objective leads to want to limit the loss of load idling. The satisfaction of the second objective and the constraint leads to want to increase these pressure drops during the phases of flight.

The present invention aims to allow a variation of the pressure losses according to the phases of flight.

Another object of the present invention is the protection of equipment against foreign objects commonly called FOD (acronym for Foreign Object Debris / Damage). In fact, in certain cases, the position of the catching cups of the ventilation flow of the nacelle allows the ingestion of numerous foreign bodies (hail, dust, gravel and even small birds). These ingestion problems can lead to the displacement of certain equipment in the area directly downstream of the scoop (which has impacts on the installation and ventilation, the best ventilated zone being the zone just downstream of the scoop). ) or to protect such equipment (impact on the mass).

The present invention aims to prevent the direct impact (without rebound) between foreign bodies of the FOD type and equipment.

Finally, in the case of a turboprop equipped with two dynamic scoops located on either side of the air intake, the dissymmetry created by the propeller located just upstream of the ventilation scoops induces an asymmetry of the feeding scoops and therefore an imbalance in the ventilation of the nacelle compartment.

The present invention aims to allow a recovery of flow rates between the two scoops in this particular type of configuration.

SUMMARY OF THE INVENTION The invention thus proposes a device for ventilating a turbomachine compartment, in particular an aircraft turbomachine, comprising an air inlet connected to a diffuser, characterized in that it also comprises a body located downstream of the diffuser, the diffuser and the body defining between them an air passage section, one of said diffuser and said body being movable relative to the other so as to modify said section, the body being further configured to deflect foreign objects that may pass through said section.

One of the main pressure drop positions between the capture and exhaust by a ventilation device is that related to the flow in the ventilation device. This pressure drop increases quadratically depending on the Mach present in the ventilation device. Advantageously, the ventilation device according to the invention makes it possible to vary the Mach in the ventilation device by modifying its passage section.

Another pressure drop position concerns the bursting of the jet in the nacelle insofar as the ventilation device feeds a bucket compartment. At first order, such bursting creates a pressure drop equal to the dynamic pressure of the air jet. Thus, to minimize these losses, a diffuser for transforming the dynamic pressure into static pressure upstream of the burst can be installed. This static pressure recovery is all the more important that the diffusion ratio (output section / input section) is large. The ventilation device makes it possible to vary this diffusion ratio.

Finally, in the case where a turboprop engine would be equipped with two ventilation devices whose feed conditions would be different, it would be possible to rebalance the flow through each of them by dissymmetry the diffusion ratio of the two ventilation devices and therefore of their losses.

The variation of the passage section and the diffusion ratio in the ventilation device is achieved by moving the body vis-à-vis the diffuser, or vice versa.

The ventilation device according to the invention can comprise one or more of the following characteristics, taken separately from one another or in combination with each other: the diffuser is extended by a duct which connects it to the air inlet , the master torque of the body being greater than the minimum radius of the duct, - the diffuser has an elongated tubular shape of longitudinal axis A, the body being aligned on the axis A, and one of said diffuser and said body being movable relative to one another in translation along said axis, - the air passage section has an annular shape, - the diffuser has a flared shape on the body side, - the body comprises an upstream ogival portion and optionally a ogive downstream portion, the body comprises an upstream portion whose section, generally of circular shape preferably, increases downstream, from an upstream end in point of almost zero cross section, to a portion of large body maximum section, - the body comprises a downstream portion whose section, generally circular in shape, preferably decreases downstream, from a portion of larger maximum section of the body to a downstream end tip of almost zero section, - the diffuser or body is movable from a first position in which said upstream portion is partially inserted into said diffuser, and a second position in which said upstream portion is substantially fully inserted into said diffuser, - the diffuser is fixed and the body is movable and connected by arms to a ring which extends around the axis A upstream of said diffuser and which is configured to cooperate with a drive means in translation of said ring and thus said body along said axis, the arms pass through the orifices of the diffuser, and the body is stationary and the diffuser is movable and configured to cooperate with at least one guide means. in translation and a drive means in translation along the axis A.

The present invention also relates to a turbomachine, such as an aircraft turboprop, comprising at least one ventilation device as described above, in particular for the air supply of a nacelle compartment.

BRIEF DESCRIPTION OF THE FIGURES The invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description which follows, given by way of nonlimiting example and with reference to the appended drawings. FIG. 1 is a schematic view of an aircraft turboprop, 3 and 4 are diagrammatic perspective views of a ventilation device according to the invention, of which a movable body is respectively in two different positions; FIG. 5 is a diagrammatic perspective view of the ventilation device of FIGS. , seen from downstream, and - Figure 6 is a very schematic axial sectional view of an alternative embodiment of a ventilation device according to the invention.

DETAILED DESCRIPTION

Reference is first made to FIG. 1 which represents a turboprop 10 for an aircraft.

The turboprop 10 here is of the double-body type and comprises a low-pressure body 12 and a high-pressure body 14, the low-pressure body 12 driving a propulsion propeller through a gearbox 16 or reduction gearbox. commonly called PGB (for Propeller Gear Box). Only the shaft 18 of the propulsion propeller is shown in FIG.

The low pressure body 12 here comprises only a turbine rotor connected by a shaft to the gearbox 16. The high pressure body 14 comprises a compressor rotor connected by a shaft to a turbine rotor. The shaft of the high-pressure body 14, called the HP shaft 20, is tubular and coaxially traversed by the shaft of the low-pressure body 12, called BP shaft 22 or power. The BP shaft 22 comprises at one end a pinion (not shown) coupled through a series of pinions of the gearbox 16 to the shaft 18 of the propulsion propeller.

The turboprop engine 10 comprises an accessory equipment drive case 24 (called accessory gearbox or AGB for Accessory Gear Box) which is coupled to the high pressure body of the turbomachine 14, and in particular to the HP shaft, by the The accessory housing 24 is mounted in the nacelle 28 of the turboprop 10, which is schematically represented by a rectangle.

The turboprop 10 further comprises an air inlet sleeve 32 for supplying air to the engine, and a exhaust nozzle 34 for exhausting the combustion gases. The turboprop 10 further comprises a combustion chamber 35 between the HP compressor and the HP turbine.

FIG. 2 represents the front or the upstream of a turboprop engine 10 according to the invention, the upstream and downstream terms referring to the direction of flow of the air around and inside the turboprop 10 operating in the entirety of this application.

It is found that the upstream end of the nacelle 28 integrates the lip of the air inlet sleeve 32, which is traversed by a substantially vertical median plane P passing through the axis of rotation of the helix. The nacelle 28 further comprises, on either side of this plane P, and substantially between the lip of the sleeve 32 and the propeller, two ventilation device 40 of the type scoops for drawing air through an inlet air 41 for the supply of an inner compartment of the nacelle 28 and the ventilation of equipment housed in this compartment. FIG. 2 makes it possible to understand that the two ventilation devices 40 are not fed identically, since when the helix rotates counterclockwise, for example, the device 40 on one side (left in the drawing) is powered by displacement of the blades in downward phase, and the device 40 located on the other side (right in the drawing) is powered by moving the blades in the rising phase.

Figures 3 to 5 show a ventilation device 40 according to one embodiment of the invention. In the example shown, this ventilation device 40 comprises, from upstream to downstream, a duct 42, a diffuser 44 and a movable body 46.

The conduit 42 and the diffuser 44 may form a single element. The conduit 42 has an elongated cylindrical and tubular shape here. It opens at its upstream end on an outer face of a nacelle hood 28 to define a supply or air intake port, and is in fluid communication at its downstream end with the diffuser 44. The conduit 42 defines a circular passage section, substantially constant along its longitudinal axis A.

The diffuser 44 has an elongate and tubular shape along the axis A. It has a flared shape on the opposite side to the duct 42. Its flared end is intended to receive the movable body 46 which is translatable in translation along the A-axis between a first position shown in Figure 3 where it is partially inserted into the diffuser 44, and a second position shown in Figure 4 where it is further inserted into the diffuser 44. The diffuser 44 and the body 46 define between them a substantially annular section of air passage, which is maximum in Figure 3 and minimum in Figure 4.

The body 46 has an ovoid shape centered on the axis A and whose upstream and downstream ends are pointed. In other words, the body 46 has an upstream portion substantially in the ogive or ogive head and a downstream portion substantially ogive or ogive head. The profiled shape of the downstream portion of the body 46 is intended to limit the pressure losses in the ventilation air flow delivered in the nacelle 28. The profiled shape of the upstream portion of the body 46 allows to assign a specific function to the body 46 which is to deflect foreign objects likely to enter the device 40. This upstream portion has for example a taper angle greater than or equal to 30 °. These foreign objects are intended to enter the conduit 42 and then into the diffuser 44 and to impact the upstream portion of the body 46 to be deflected radially outwardly of the axis A. Sensitive equipment that would be disposed downstream of the device 40 would not risk receiving foreign objects. The equipment that would be arranged laterally could receive foreign objects after rebound (that is to say, after losing much of their kinetic energy, and therefore harmless). They would not receive foreign objects at full speed.

The body 46 is here connected by longitudinal arms 50 to a ring 48 mounted around the conduit 42. The ring 48 may optionally be placed around the diffuser 44, it depends on the respective lengths of the conduit 42 and the diffuser 44. In all case, the ring 48 is preferably arranged upstream of the flare of the diffuser 44.

The arms 50 are here three in number and are evenly distributed around the axis A. The ring 48 is slidably mounted along the axis A on the duct 42 or a portion (upstream) of the diffuser 44. It has an outer diameter less than or equal to the diameter of the flared end of the diffuser 44. The longitudinal arms 50 are inscribed in a cylinder surrounding the ring 48 and the diffuser 44 and pass through the orifices 52 of the diffuser. This limits the size of the device 40 but the arms 50 could alternatively not pass through the diffuser 44 but simply extend longitudinally around it.

Although not shown in the drawings, the ring 48 carries a longitudinal rack (not shown) which is engaged with a pinion 54 whose axis of rotation is perpendicular to the axis A.

The displacement of the ring 48 and therefore of the body 46 is achieved by the rotation of the pinion 54 which is caused by a drive means such as an electric motor (not shown).

In addition to allowing a modification of the passage section, the displacement of the body 46 in the diffuser 44 makes it possible to vary the diffusion ratio of the diffuser 44. The position of FIG. 3 is particularly adapted to an idle speed, the device 40 to provide a high dilution ratio. The position of Figure 4 is particularly suitable for a cruise regime, the device 40 then providing a low diffusion ratio.

The obstructing body 46 is preferably shaped to minimize the pressure losses it generates. The race of the rack must be sufficiently large to be able to clear almost completely the body 46 of the diffuser 44. The arms 50 transmitting the translational force are preferably sufficiently robust to maintain a good concentricity between the body 46 and the diffuser 44. They will have to be profiled and relatively thin, in order to limit the losses caused by their wakes.

The master torque of the obstructing body 46 is preferably greater than the minimum radius of the duct 42. This is indeed because the diameter of the body section is greater than the diameter of the air intake duct, that the objects strangers are correctly deflected. This specificity therefore enables it to fulfill its protection function against direct FOD impacts. For example, the ring 48 may be made of metal. The movable body 46 may be made of plastic or composite. A ball bearing may be integrated between the conduit 42 or the diffuser 44 and the ring 48 to guide the translation thereof.

Referring now to Figure 6 which shows a variant of the device 40 'according to the invention. In contrast to the previous embodiment, the diffuser 44 'of the device 40' is here mobile and its body 46 'is fixed.

The body 46 'is fixedly mounted inside the nacelle 28, here on a fixed wall 28' of the latter. It is aligned on the axis A and disposed upstream of a device 56 for its protection against FOD. The body 46 'is mounted on the wall 28' by means of arms 50 'which comprise portions extending substantially parallel to the axis A and which are configured to form translational guiding means of the diffuser 44'.

The duct 42 'is connected to the air inlet 41' and comprises a cylindrical guiding portion on which is mounted an upstream end of the diffuser 44 '. The diffuser 44 'has an elongated cylindrical shape with a longitudinal axis A. It is mounted at its upstream end on the cylindrical portion of the duct 42' and at its downstream end inside the arms 50 'which guide it. In the example shown, the diffuser 44 'comprises an upstream cylindrical portion of smaller diameter which is slidably mounted longitudinally along the axis A on the cylindrical portion of the duct, and a downstream cylindrical portion of larger diameter which is mounted in longitudinal sliding along the axis A inside the arms 50 '.

As in the previous embodiment, the displacement in translation can be achieved by a pinion 54 'which meshes with a rack, here of the diffuser 44', and which is itself driven by an electric motor for example.

Claims (11)

1. Ventilation device (40, 40 ') of a turbomachine compartment, in particular an aircraft turbomachine, comprising an air inlet (41, 41') connected to a diffuser (44, 44 ') , characterized in that it further comprises a body (46, 46 ') located downstream of the diffuser, the diffuser (44, 44') and the body (46, 46 ') defining between them a passage section of air, one (46, 44 ') among said diffuser and said body being movable relative to the other (44, 46') so as to modify said section, the body (44, 44 ') being further configured to deflect foreign objects likely to cross said section. 2. A ventilation device (40, 40 ') according to claim 1, wherein the diffuser (44, 44') is extended by a conduit (42, 42 ') which connects it to the air inlet, the master body torque (46, 46 ') being greater than the minimum radius of the duct (42, 42'). Ventilation device (40, 40 ') according to claim 1 or 2, wherein the diffuser (44, 44') has an elongate tubular shape with a longitudinal axis A, the body (46, 46 ') being aligned with the axis A, and one of said diffuser and said body being movable relative to the other in translation along said axis. 4. Ventilation device (40, 40 ') according to any one of the preceding claims, wherein the air passage section has an annular shape. Ventilation device (40, 40 ') according to claim 3 or 4, wherein the diffuser (44, 44') has a flared shape on the body side (46, 46 '). 6. Ventilation device (40, 40 ') according to one of claims 3 to 5, wherein the body (46, 46') comprises an upstream ogival portion and optionally a downstream portion ogive. 7. Ventilation device (40, 40 ') according to the preceding claim, wherein the diffuser (44, 44') or the body (46, 46 ') is movable from a first position in which said upstream part is partially inserted in said diffuser, and a second position wherein said upstream portion is substantially fully inserted into said diffuser. 8. Ventilation device (40) according to one of claims 3 to 7, wherein the diffuser (44) is fixed and the body (46) is movable and connected by arms (50) to a ring (48) which extends around the axis A upstream of said diffuser and which is configured to cooperate with a means (54) for driving in translation said ring and therefore said body along said axis. 9. Ventilation device (40) according to the preceding claim, wherein the arms (50) pass through the orifices of the diffuser (44). 10. Ventilation device (40 ') according to one of claims 3 to 7, wherein the body (46') is fixed and the diffuser (44 ') is movable and configured to cooperate with at least one guiding means. translation and translation drive means (54 ') along the axis A. 11. A turbomachine, such as an aircraft turboprop, comprising at least one ventilation device (40, 40 ') according to one of the preceding claims, in particular for the supply of air to a nacelle compartment.