阅读说明：本技术 用于穿过飞行器发动机的壁喷射热气体的出口 (Outlet for injecting hot gases through the wall of an aircraft engine ) 是由 克里斯蒂安·哈达德 丹尼尔·德·巴罗斯·苏亚雷斯 克劳德·皮埃尔·乔安那斯·杜宾 巴斯蒂安·皮 于 2019-08-19 设计创作，主要内容包括：一种用于从飞行器发动机排出热空气的管道(4)由可以从壁(1)上突出的可动的堆叠件(13)延伸,使得热空气在与壁(1)相距一距离处被喷射,而不会引起损坏壁的风险。然而,堆叠件(19)可以在中等的发动机速度的情况下通过控制设备(14)缩回,其优点在于,减少了通常为外机舱的壁的阻力。(A duct (4) for discharging hot air from an aircraft engine extends from a movable stack (13) that can protrude from a wall (1) so that the hot air is injected at a distance from the wall (1) without risking damage to the wall. However, the stack (19) can be retracted by the control device (14) at moderate engine speeds, which has the advantage that the drag of the wall, which is usually the outer nacelle, is reduced.)

1. An outlet (2) for injecting hot gases through a wall (1) of an aircraft engine, comprising at least one opening (7) through the wall, ducts (4, 6) for conveying the hot gases leading to the opening (7), and a stack (13) associated with the opening and in the shape of a sleeve projecting from the wall (1), wherein the stack is separate from the wall, is movably engaged through the opening (7), and is provided with a movement control device (14; 30) which varies the projection height (H) of the stack from the wall, characterized in that it comprises temperature-sensitive motor means (17, 22; 30) without any autonomous control.

2. The jet outlet according to claim 1, characterized in that the control device comprises a sensor (22) having the temperature and an electric motor (17) controlled by the sensor.

3. The ejection outlet of claim 1, characterized in that the motor means comprise an inert actuator (30) which changes state as a function of temperature.

4. The jet outlet according to any one of claims 1 to 3, characterized in that the temperature is the temperature of the wall (1) downstream of the opening (7) or the temperature of the hot gas in the duct (4).

5. The ejection outlet according to any one of claims 1 to 4, characterized in that it comprises means (34) for returning the stack (13) to the fully deployed position with a maximum projection height from the wall in the event of inactivity or failure of the control device.

6. The injection outlet according to any one of claims 1 to 5, characterized in that the movement is inclined between two stable positions of the stack according to the crossing of a temperature threshold of the wall (1) or of the hot gases in the duct (4).

7. The jetting outlet of any one of claims 1 to 6, wherein the stack has continuous walls, with no openings.

8. The ejection outlet according to any one of claims 1 to 7, characterized in that the stack (13) is cylindrical and the control device is arranged to impart to the stack a translational movement perpendicular to the wall (1) by sliding in the opening.

9. The jetting outlet according to any one of claims 1 to 8, wherein the stack is movable to a fully retracted position below the wall with a zero protrusion height (H).

10. The ejection outlet according to any one of claims 1 to 9, comprising a plurality of said openings (7), each provided with said stack (13) and distributed on said wall (1), characterized in that said stack motion control devices are independent from each other.

11. The jet outlet of any one of claims 1 to 10, wherein the projection height varies in accordance with the flight speed of an aircraft.

Technical Field

The invention relates to an outlet for injecting hot gases through a wall of an aircraft engine.

Background

The outlet may be used at the end of a hot gas duct of an aircraft engine, which belongs to a heat exchange circuit that draws cooled gas (typically air) from a relatively cold region of the aircraft, such as a compressor that is the secondary flow path (if present) or the primary flow path, and then is heated in a heat exchanger by a hotter portion of the engine that should be cooled or another fluid (e.g., lubricating oil or gas). The heated gas is then released into the external environment through an outlet (also called a jet grid) consisting of one or more openings through the wall of the aircraft, such as an external nacelle cover or an external or internal stator housing.

Sometimes, the hot gas is discharged at a higher temperature than what can be tolerated by the material of the walls without damage, the temperature at which the hot gas is washed before dispersion and thus the temperature at which degradation occurs around the openings of the spray grid.

An example of such an outlet that may be subject to such difficulties can be found in document FR 3015569 a.

This risk of damage can be avoided by early separation of the hot gas in order to keep it away from the wall near the outlet. A flow of relatively cold gas is utilized as follows: the cooler gas is normally circulated on the exterior face of the wall during engine operation by the maintenance protective layer. The hot gas is rapidly mixed with the cold gas and becomes harmless before the hot gas may return to the wall.

This effect can be provided by means of what are known as stacks which are placed on the openings while projecting from the wall into the cold spray environment, thereby releasing the hot gas at a distance from the wall on which a protective layer of cold ambient gas is maintained during flight.

The stack may be aerodynamically shaped to have reduced drag, but not completely removed. One disadvantage of the protruding stack is therefore a reduction in engine efficiency.

The invention is based on the following idea: the protection of the walls of the nacelle is not required during the entire flight, but only during certain specific conditions of flight (when the engine is running at full speed, while it is not in cruise mode, in which the flow rate of the hot gases is almost zero). The idea is therefore to take these different conditions into account at different flying speeds to adapt the design of the jetting apparatus.

The object of the invention is to vary the projection height of the stack above the wall of the engine, depending on the situation, in particular the flying speed, mainly in order to reduce this projection height and the corresponding drag as quickly as possible.

EP 2275655 a2 describes an expandable stack of which the walls are provided with openings to ensure a larger working surface when the flow rate to be discharged increases. The spread of the stack depends on the increase in pressure drop required across the stack due to the increase in flow rate.

EP 1728992 a2 describes an inlet valve for a circuit for sampling gas circulating in a flow path, the rise of which is variable in the flow path to open the valve more or less.

Disclosure of Invention

In general, the invention relates to a spray outlet of the above-mentioned type and comprising at least one opening through the wall, a duct for conveying hot gas leading to the opening, and a stack associated with the opening and in the shape of a sleeve projecting from the wall, wherein the stack is separate from the wall, is movably engaged through the opening, and is provided with a motion control device which varies the projection height of the stack from the wall.

The control means do not rely on external actions originating from another system or exerted by an operator, such as the pilot of the aircraft, but instead apply automatic control. The control means comprises temperature sensitive motor means for deploying or retracting the stack in dependence on the measured or sensed temperature.

The invention may be applied to a single open outlet. However, a commonly used apparatus comprises a plurality of such openings constituting a spray grid, each of these openings being provided with a stack as described above. Thus, according to a preferred embodiment of the invention, the devices for controlling the movement of the stack are independent of each other, so as to limit possible failure results in only one of the openings.

According to one embodiment of primary concern, the stack is cylindrical and the control device is arranged to impart to the stack a translational movement perpendicular to the walls by sliding in the opening: the corresponding device is particularly easy to design and construct.

The term "cylindrical" as used in this application covers all forms of entity defined by a surface whose generatrices are parallel and two end surfaces. Thus, the cylindrical stack may have a circular, oval or even any cross-section.

According to a second embodiment, the stack has a rectangular cross-section.

The temperature measurement may be made by a sensor, such as a thermocouple, positioned on the surface of the nacelle cover, which controls the power supply circuit of the motor actuating the control device. However, an arrangement without a characterized motor is also advantageous: the device may consist of a passive actuator of the movement of the stack, which is able to perform a change of state as a function of temperature. The above temperatures are representative temperatures at which the wall is supposed to be heated. The temperature mentioned above may comprise the temperature of the wall (in particular downstream of the hot gas injection outlet) or the temperature of the gas in the duct.

In case of inactivity or failure of the control device, safety may be provided by means for returning the stack to the fully deployed position (i.e. at the maximum protrusion height from the wall). The return means then maintain the stack in a state in which it is most able to protect the walls by preventing hot gases from falling on them.

Advantageously, the stack may have a fully retracted position below the wall, corresponding to a zero projection height, in order to minimize resistance.

Finally, it is still advantageous that, in order to enable a simplification of the control, the movement of the stack is tilted between two stable positions according to the crossing of the temperature thresholds, that is to say the stack is completely extended or completely retracted, the intermediate state not necessarily being meaningful.

More generally, however, the projection height of the stack can be determined by the flight speed of the engine of the aircraft; for example, high altitude at high takeoff or acceleration, and very low or zero altitude at low speed (e.g., cruise).

Drawings

Various aspects, features and advantages of the present invention will be described in more detail, with the following figures showing some embodiments of the invention, given by way of illustration only:

figure 1 shows the absence of an injection grid on an aircraft engine;

figure 2 schematically shows a jet;

figure 3 shows the gas flow at the grid;

figure 4 shows the effect of the stack at the openings of the grid;

figures 5 and 6 show a first embodiment of the invention with two operating states;

figure 7 shows a device for controlling the movement of the stack; and

fig. 8 and 9 show a second embodiment of the invention with two operating states.

Detailed Description

Fig. 1 schematically shows a nacelle cover surrounding an aircraft engine, the wall 1 of which is provided with an outlet 2 through which a heat exchange circuit 3 located below the wall 1 opens to the outside of said wall and which emits a jet of gas previously extracted from another part of the engine and participating in the heat exchange. It should be recalled that the invention is not limited to use on nacelle covers, but that the invention may also relate to other covers, such as covers of external or internal stator housings. Likewise, the heat exchange circuit 3 can originate from various locations in the engine, without imposing restrictions on its path, and the heat exchange allows cooling of another fluid that is also incidental.

Refer to fig. 2. The heat exchange circuit 3 comprises at its downstream end a tube 4 extending below the inner face 5 of the wall 1. At a position close to the wall, the tube 4 is divided into branches 6, which are different from each other here and then parallel, and whose cross section first decreases and then becomes uniform before reaching the wall 1 and the outlet 2; and the branch 6 is connected to the wall 1 and communicates with the outside of the wall 1 through a number of openings 7 of the outlet 2 through the wall 1. The arrangement of these branches is better seen in fig. 3. The openings 7 are parallel to each other, follow each other in a transverse direction T (generally the angular direction of the engine), and are oblong in shape, their largest dimension being in a longitudinal or main direction of elongation X perpendicular to the direction on the wall 1 (generally the axial direction of the engine). The length of the opening 7 in the direction X may be between 100mm and 450 mm; the width of the opening 7 in the direction T may be between 5mm and 30 mm; the width of the spray grid formed by the outlet 2 in the direction T may be between 250mm and 600 mm; and the total area of the outlets 2 may be about 0.01m²To 0.25m²To change between. However, there is no practical size limitation on the application of the present invention. And the openings 7 are separated by a sheet 8 of the wall 1, the width of this sheet 8 being between 0.5 and 3 times, preferably 1.0 times, the width of the openings 7.

The hot gas (generally air) injected by the circuit 3 is therefore divided into thermal streamlets 9 employing the respective branches 6. The direction of these thermal streamlets can be first carried out in the direction of height R (perpendicular to the two aforementioned directions X and L and generally coinciding with the radial direction of the engine) by rising below the outer face 12 of the wall 1 opposite the inner face 5, then turned and following the motion component in the longitudinal direction X by the action of an outer flow 10 of cold gas (generally ambient air) tangential to the wall 1 (generally directed downstream of the engine). However, the flow 10 is divided into cold thin flows 11 which pass around the opening 7 and over the lamellae 8, over the outlet 2, with a large flow rate which remains tangential to the wall 1. This flow rate of the cold gas prevents the return of the hot streamlets 9 on the outer face 12 of the wall 1 and protects them from overheating. In addition, the division of the hot and cold air streams into interlaced thin streams 9 and 11 promotes faster mixing of the hot and cold air streams, thereby eliminating the hot region outside the outlet 2.

Fig. 4 shows a possible arrangement of stacked spray grids, in which the branches 6 of the circuit and the openings 7 extend through stacks 13 projecting on the outer face 12 of the wall 1. With this arrangement, the height of the stack 13 can typically be a few millimeters or centimeters. The heat streamlets 9 leave the heat exchange circuit 3 through the upper edge 20 of the stack 13 at a distance from the wall 1, which helps to maintain the cold air streamlets between the openings 7.

A description will now be made with respect to fig. 5 and 6. The stacks 13 are not fixed to the engine structure, in particular to the wall 1, but, instead, are separate from the engine structure, in particular the wall 1, and each comprise a cylindrical sleeve, that is to say, each stack has a constant section which, with the exception of a small clearance, is identical to that of the opening 7 through which it engages. The cross section of these stacks may be rectangular, as shown in particular in fig. 3, with two long, straight and parallel sides in the axial direction X, and two short, rounded sides. The walls of these stacks are continuous and do not have any openings. In addition, the stacks are movable. Advantageously, the movement of these stacks is sliding and is done by a control device 14 comprising, in a housing 15 hinged at a fixed point 16 of the structure of the aircraft engine, an electric motor 17, a movement transmission gear 18 and a worm 19 meshing with the transmission 18, perpendicular to the wall 1 and hinged to the stack 13.

The control device 14 exerts a translational movement on the stack 13 in the direction of the worm 19, the effect of which is to slide in the branch 6 by varying the projection height H of the stack projecting above the outer face 12 between a maximum value (corresponding to the fully extended position shown in fig. 5) and a minimum value (wherein the projection height may also be zero, that is to say the stack 13 is fully retracted in the branch 6 and the outer face 12 is smooth (fig. 6)). The first position is used when the wall 1 is subjected to a very high temperature during injection of very hot gases, whereas the second position is used in other cases (when the cooling demand of the aircraft engine is low and the hot gas flow is reduced or the gases are at a lower temperature). The open cross-section of the stack 13 is the same in both conditions and must be sufficient to exhaust all the predictable airflow without resisting significant pressure drop.

The control device 14 can be controlled by means shown in fig. 7, which comprise an electric circuit 21 or a thermocouple 22, which is a temperature sensor positioned, for example, on the external face 12 of the wall 1 downstream of the opening 7 of the outlet 2, which controls two switches 23 and 24 capable of placing a terminal 25 of the electric motor 17 at one of the positive and negative poles of a constant potential difference 26. Thus, the circuit 21 allows the electric motor 17 to rotate in one direction or the other. Switching is performed when thermocouple 22 detects that the temperature of wall 1 becomes higher or lower than a threshold value.

The circuit 21 is completed by end-of-travel contacts 27 and 28 provided at the terminals of the motor 17, which open the circuit 21 to stop the movement when the limit is reached. A device is obtained which is purely passive in that it does not exert any external control but is simple and reliable. Also, the device is bistable between the fully deployed position and the fully retracted position, which is desirable because intermediate deployment is not meaningful in this application and can ensure the robustness of the device.

A further control device 29 is described with the aid of fig. 8 and 9, which control device 29 has some similar properties, but which has an even simpler construction. The control device comprises a deformable structure 30 mounted to a fixed structure 31 of the engine and carrying a smooth rod 32, which replaces the worm 19 and carries the stack 13. The deformable structure 30 is bistable between two states in which it has different shapes, so as to impose two different deployment positions on the stack 13, as described above. The deformable structure 30 may be formed by a thermostat bimetal made of a shape memory alloy. The switching from one state to the other may be controlled, for example, by the temperature of the hot gas to which the deformable structure 30 is exposed through a communication duct 33 leading to the duct 4.

Despite the weight increase imposed by the control device 14, a significant gain in fuel consumption of the engine equipped with the invention has been observed, due to the possibility of retracting the stack 13 at most flight speeds. The reliability of these control devices is good due to their robustness. Furthermore, in some designs, it is possible to add a return device (part 34 in fig. 5 and 6) in the shape of a spring tending to move the stack 13 to its fully deployed position, which is therefore a safe position preventing damage to the wall 1 in all cases. However, the force of the spring 34 can be overcome by the motor 17 so as not to impede the operation of the device and is only forced to the fully deployed position in the event of any damage or inactivity of the control device (e.g. engine failure or transmission 18 damage). The connection between the transmission 18 and the worm 19 must then be kinematically reversible.

In the usual case with a plurality of openings 7, each opening is advantageously controlled by a separate device similar to those already described, so that the failure of one of these devices is still localized at the respective opening 7.

In general, the means for triggering the deployment and retraction of the stack, which is sensitive to the crossing of certain temperature thresholds, may be a sensor that measures the temperature and sends the measurement to a control device, or the stack actuator itself, which is configured to change state based on the temperature.