JPH04311633A - Gas turbine engine - Google Patents

Abstract

PURPOSE:To provide a gas turbine engine capable of reducing intake resistance and improving the efficiency of a compressor. CONSTITUTION:Inside a compressor shroud 3 for guiding air flowing into a compressor of a gas turbine engine is disposed concentrically with a compressor impeller 2 a bugle-like pipe 5 having the minimum inner diameter portion smaller than the minimum inner diameter value of the compressor shroud 3 and the inner diameter portion nearly equal to the inner diameter of an air inlet of the compressor shroud so that the bugle-like pipe 5 can be moved in the direction of the center axis A of the compressor.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas turbine engines, and more particularly to gas turbine engines capable of varying the amount of air flowing into a compressor depending on operating conditions.

0002

BACKGROUND OF THE INVENTION In recent years, a gas turbine engine generates power by introducing high-pressure air from a compressor into a combustion chamber and combusting it, and then blowing the combustion gas against a turbine rotor to rotate a turbine. It is attracting attention as an internal combustion engine for driving vehicles.

Generally speaking, in order to increase the efficiency of this gas turbine engine, it is essential to increase the efficiency of the compressor, and the efficiency of the compressor is determined by the angle ( It is known that the smaller the angle of attack (generally called the "angle of attack"), the better.

However, when using a gas turbine engine for a general vehicle where the engine speed changes over a wide range from a low speed range to a high speed range,
Since the amount of air taken into the compressor changes, it is impossible to always take air into the compressor with a constant angle of attack in response to changes in the rotational speed of the compressor impeller. Even if they are matched, the compressor efficiency will deteriorate in an operating range that deviates significantly from this operating range, resulting in extremely poor engine performance.

[0005] For such problems, for example, Japanese Patent Application Laid-Open No. 1983
In Publication No. 97835, a large number of variable inlet guide vanes are provided at the inlet of the compressor, and by driving the guide vanes, the direction of air inflow into the compressor is variably controlled according to the amount of air, thereby controlling the entire operation. A gas turbine engine is disclosed that attempts to increase the efficiency of a compressor in the area.

[0006]

[Problems to be Solved by the Invention] However, the above-mentioned gas turbine engine has a large number of variable inlet guide vanes disposed circumferentially at the entrance to the compressor. The problem is that the mechanism for driving both at the same time is quite complex, the manufacturing cost is high, and the assembly itself requires considerable skill. In addition, since a large number of guide vanes are usually provided depending on the number of blades of the compressor impeller, depending on the design of the guide vanes, this may create resistance to intake air, which may actually reduce the efficiency of the compressor.

[0007] In view of the problems of the prior art, the present invention
It is an object of the present invention to provide a gas turbine engine that has a simpler structure than the conventional technology and can reduce intake resistance.

[0008]

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a minimum inner diameter portion smaller than the minimum inner diameter of the compressor shroud is provided on the inside of the compressor shroud that takes air into the compressor of a gas turbine engine. A gas turbine engine is provided, in which a wrapper tube having an inner diameter approximately equal to the inner diameter of the air intake port of the compressor shroud is arranged concentrically with the compressor impeller, and the wrapper tube is movable in the direction of the central axis of the compressor. be done.

[0009]

[Function] The air inlet area of the compressor can be varied by changing the position of the trumpet tube in the central axis direction of the compressor, which changes the flow velocity of the air taken into the compressor and changes the angle of attack of the compressor impeller blades. can. As the name suggests, the wrapper tube resembles the shape of the compressor shroud and extends inside it, so it has less intake resistance than conventional devices that have multiple obstacles (guide vanes) in the intake passage, and because it is a single component. The drive mechanism can also be simplified.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cross section of a compressor portion of a gas turbine engine as an embodiment of the present invention, in which 1 is a rotor shaft extending from a turbine rotor (not shown), and 2 is a compressor fixed to this compressor shaft 1 and rotationally driven. The impeller 3 is a compressor shroud that surrounds the compressor impeller 2 and defines a ventilation passage before and after compression, and 4 is a bearing holder for a bearing (not shown) that supports the rotor shaft 1, and is a stationary component together with the compressor shroud 3. Further, the dashed line A is the central axis of the compressor.

[0011] The compressor shroud 3 has a minimum inner diameter value at a point where the end 2a of the compressor impeller 2 on the intake upstream side is located, so that a large amount of air can be taken into the compressor impeller 2, The inner diameter value gradually increases toward the intake side, and the inner diameter value also increases toward the downstream side of the intake air, so that the compressor impeller 2 has a shape complementary to the outer shape of the compressor impeller 2.

In the compressor section of the gas turbine engine configured as described above, according to this embodiment, the compressor shroud 3 is located inside the compressor shroud 3 and on the upstream side of the intake air of the compressor impeller 2.
A trumpet tube 5 having a shape substantially similar to the inner peripheral contour shape is provided concentrically with the compressor impeller 2 when viewed from the direction in which the central axis A extends.

The trumpet tube 5 has the above-mentioned minimum inner diameter value Ismin. of the compressor shroud 3. A value even smaller than Irmin. The inner diameter of the compressor shroud 3 is gradually increased from the end 5a to the intake upstream side (rightward in the figure), and at the other end 5b, the air of the compressor shroud 3 is Intake port inner diameter value Ismax. A value approximately equal to Irmax. (Strictly speaking,
(a value obtained by subtracting the tube thickness of the wrapper tube 5). That is, the trumpet tube 5 in this embodiment is formed to have a larger curvature than the inner peripheral curvature from the minimum inner diameter portion of the compressor shroud 3 to the air intake portion when viewed in its longitudinal section as shown in the figure. .

In addition, according to this embodiment, the trumpet tube 5
A suitable support member 6 such as a rod or plate is connected to the , and an actuator mechanism 7 such as a hydraulic cylinder is used to move the compressor impeller 2 along the central axis A (
That is, it is installed so as to be movable (in the direction in which the compressor shaft 1 extends). Furthermore, the drive of this actuator mechanism 7 is controlled by a drive signal from a control circuit 8 depending on the operating conditions of the vehicle equipped with the gas turbine engine, so that the compressor efficiency can be increased over all operating conditions. For example, when the engine is in idle operation, the trumpet tube 5 occupies the position as shown in FIG. The trumpet pipe 5 is controlled to be displaced to the upstream side of the intake air from the position 1.

As shown in FIG. 3(a), the smaller the angle of inflow of air to each blade of the moving compressor impeller 2, that is, the angle of attack Δi, the smaller the resistance to the rotation of the impeller blades, and as a result, the compressor impeller It is based on the principle that efficiency can be increased.

Specifically, as shown in FIG. 3(b), when focusing on one impeller blade, the angle of attack Δ
i is the relative air inflow vector (the air inflow vector seen from the impeller blade) determined by the circumferential velocity vector of the impeller blade and the inflowing air flow vector at right angles to this, and This is the angle formed by the tangent line t at the tip of the center line. For example, as shown in Fig. 4, the compressor shroud and impeller are adjusted so that the angle of attack Δi at the compressor impeller inlet is as small as possible at the rated time when the engine output is 100%. When the blades are designed, during operation where the engine output is smaller than this, both the circumferential speed of the impeller blades and the air flow velocity decrease as the engine output decreases, but the rate of decrease in the circumferential speed of the impeller blades is Since the rate of decrease in flow velocity is large, the angle of attack Δi becomes relatively large, and the compressor efficiency decreases accordingly (see the dotted line in FIG. 3).

Therefore, during idling operation when the compressor efficiency is lowest, the wrapper tube is arranged so that the intake upstream end 5a of the wrapper tube 5 contacts the air intake port of the compressor shroud 3, as shown in FIG. 5, the minimum inner diameter value Irmin. is the minimum inner diameter value Ismin. of the compressor shroud 3. Since the air flow rate is smaller than the above, the air flow velocity increases due to the throttling effect, and the angle of attack Δi decreases, making it possible to improve the compressor efficiency (see point (a) in FIG. 3).

[0018] This improvement in compressor efficiency during idling means that a predetermined idling rotation can be achieved with less fuel consumption, thus improving fuel efficiency and suppressing the exhaust temperature during idling to a low level. Heat damage to gas turbine engine parts caused by exhaust gas can be prevented. Further, as is clear from the figure, the trumpet tube 5 provided inside the compressor shroud 3 has a shape similar to and complementary to the inner peripheral contour shape of the shroud 3, so that a large number of variable guide vanes are provided inside the shroud. The intake resistance can be significantly reduced compared to a structure in which the trumpet tubes are arranged circumferentially, and in addition, when comparing the drive mechanism, the trumpet tube 5 of this embodiment is a single component, so it is simpler than the conventional structure described above. It also reduces manufacturing costs.

Note that the trumpet tube 5 in other operating conditions
Regarding the axial positioning of the trumpet tube 5, as described above, it is preferable that the trumpet tube 5 occupies a position as shown in FIG. 2 at least when the engine is rated. This connects the intake upstream end 5b of the wrapper pipe 5 to the compressor shroud 3.
By moving the air intake upstream side of the air intake end 3a, air is taken into the compressor from between the outer wall 5c of the trumpet tube 5 and the shroud inner wall surface 3b, thereby increasing the amount of air. compressor efficiency,
Rated conditions matched to maximize efficiency (
This is to restore the condition as close as possible (same as without the trumpet tube). In addition, in the operating range between idling and rated conditions, for example, depending on the detected engine output,
It is preferable to linearly drive and control the actuator mechanism so as to occupy continuous positions between the trumpet tube position shown in FIG. 3 and the trumpet tube position shown in FIG.

In addition to the above-mentioned effect of improving compressor efficiency, this embodiment also improves the surging phenomenon that tends to occur during transient times such as during vehicle acceleration (which occurs because the air flow rate is small relative to the rotation of the compressor impeller). This has the effect of suppressing unstable driving phenomena.

In other words, this surging phenomenon generally occurs more easily as the circumferential speed of the impeller increases; in other words, the surging phenomenon tends to occur closer to the outer periphery of the impeller inlet. As shown in 5, the trumpet tube 5 is displaced further upstream of the intake air than its rated position. As a result, the air passage 9 between the wrapper tube outer wall 5c and the compressor shroud inner wall 3b is narrowed down even more than at the rated time due to the increased inlet area (because the outlet area does not increase much), and the air passage 9 between the compressor shroud inner wall The flow velocity Ve of the air flowing near 3b is higher than the air flow velocity Vi passing through the inside of the trumpet tube 5, and also increases compared to the air flow velocity near the inner wall of the compressor shroud at the rated time, so the air flow rate increases accordingly. This makes it possible to reduce the tendency for surging to occur.

In the above-described embodiment, the means for moving the trumpet tube 5 in the axial direction is the actuator mechanism 7 via the support member 6, but the present invention is not limited to this embodiment. In addition, the bearing holder 4 (
A mechanism may be provided inside the structure shown in FIG. 1) to drive the trumpet tube 5, or the trumpet tube 5 may be driven by penetrating the shroud 3 from the back side of the compressor shroud 3. Any mechanism may be used as long as it does not extremely increase the intake resistance.

[0023]

As described above, according to the present invention, a wrapper tube similar to the shroud shape is provided inside the compressor shroud, and this is driven from the outside by an actuator mechanism. It is simpler than conventional gas turbine engines with variable guide vanes, and intake resistance can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a compressor portion of a gas turbine engine according to the present invention, showing the trumpet tube position at idle.

FIG. 2 is a partial cross-sectional view of the compressor similar to FIG. 1, showing the trumpet tube position at rated conditions;

FIG. 3 explains the solution principle according to the present invention, in which (a) shows a model of the positional relationship between the compressor impeller blades and the air flowing into the compressor, and (b) shows a velocity triangle at the impeller inlet. It is.

FIG. 4 is a diagram comparing changes in angle of attack and compressor efficiency corresponding to changes in engine output between the present invention and the conventional system.

FIG. 5 is a partial sectional view of the compressor, similar to FIGS. 1 and 2, showing the position of the trumpet tube when suppressing the occurrence of a surging phenomenon, and showing the air flow velocity by the size of the arrow.

[Explanation of symbols]

1...Rotor shaft 2...Compressor impeller 3...Compressor shroud 5...Trumpet pipe A...Center axis of the compressor

Claims (1)

[Claims] 1. A compressor shroud that takes air into a compressor of a gas turbine engine has a minimum inside diameter portion smaller than the minimum inside diameter of the compressor shroud and an inside diameter portion approximately equal to the inside diameter of the air intake port of the compressor shroud. A gas turbine engine having a trumpet tube disposed concentrically with a compressor impeller, and in which the trumpet tube is movable in the direction of the center axis of the compressor.