JPH0979195A - Compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a sufficient air flow rate in the vicinity of the rotor blade end even when an air outflow port is throttled, and attain stable operation of a compressor even in a flow rate area lower than an original rotating/stall occurrence point by controlling the shielding area of an air passage by a flap according to an inflow air quantity. SOLUTION: A throttle quantity of air on the air outflow side increases, and when an air flow rate flowing in a compressor 1 becomes equal to or smaller than a specific value, an actuator 4a is actuated by a detecting signal from a sensor such as a pressure gauge arranged in an air passage of the compressor 1, and is controlled so that an inclination θ of a flap 3 expands. This inclination θ is controlled so as to become large as an air flow rate of the compressor 1 reduces. Therefore, the central hub side of the air passage of the compressor 1 is shielded (as an oblique line X) by the flap 3, and a stable stall area is formed. Therefore, a sufficient air flow rate can be secured on the external case side, and occurrence of a rotating/stall can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to compressors for gas turbines for aeronautical and marine vessels (compressors here are used in a broad sense including fans).

[0002]

2. Description of the Related Art In a compressor, if the number of rotations is kept constant and the outlet is throttled to reduce the air flow rate, an unstable phenomenon called a rotating stall occurs at a certain point. This phenomenon not only deteriorates the performance of the compressor but also violently vibrates the blade.

[0003]

Conventionally, an effective method for detecting the occurrence of a rotating stall and preventing the occurrence of the rotating stall has not been put into practical use. It is designed and operated in an operating range with a sufficient margin in preparation for a stall, and the low flow capacity of the compressor has not been fully utilized at present. It should be noted that FIG. 4 shows general characteristics of a conventionally used axial flow compressor, in which the vertical axis represents pressure and the horizontal axis represents air flow rate.

By the way, as a result of intensive studies on the mechanism of the occurrence of the rotating stall, the present inventors found that
The following findings were obtained. That is, when the air flow rate is reduced by narrowing the outlet of the compressor, at the time point indicated by A in FIG. , The shaded area indicates the stall area), and a sufficient flow rate is secured in the remaining passages. Then, the stall region is generated / expanded from the rotor blade tip and rotates in the circumferential direction at a speed of about half of the rotor rotation speed. This is the partspan rotating stall. Further, when the outlet is narrowed down, the stall region greatly expands in area over the full span as shown by B in the figure, and the pressure characteristic suddenly deteriorates. In other words, it is a full-span rotating stall.

Rotating stall has a large hysteresis once it occurs, and it cannot be recovered unless the throttle of the outlet is wide open (see BD in the figure), and the throttle of the outlet of an aeronautical gas turbine engine can be freely opened. If it cannot be controlled, a stagnation rotating stall that cannot be recovered without stopping the engine may occur.

The present invention is based on the knowledge that the above-mentioned stall region is generated and expanded from the rotor blade tip, and a sufficient air flow rate is secured near the rotor blade tip even when the outlet is narrowed. It is an object of the present invention to provide a compressor that can operate stably even in a low flow rate range from the original rotating stall occurrence point.

[0007]

In order to achieve the above object, in the invention according to claim 1, the shielding member for shielding the hub side at the center of the air inlet can change the shielding area of the air passage. It is characterized in that it is provided and the shielding area by the shielding member is controlled according to the amount of inflowing air.

According to a second aspect of the present invention, the shielding member is composed of a plurality of flaps, one end of which is rotatably connected to the nose cone of the air inlet, and which are arranged side by side in the circumferential direction. And

According to a third aspect of the present invention, there is provided flap inclination angle adjusting means for changing the inclination angles of the plurality of flaps according to the amount of inflowing air.

[0010]

1 is a side sectional view showing an embodiment in which the present invention is applied to a compressor for an aircraft gas turbine. In this figure, reference numeral 1 indicates an axial flow compressor, and the compressor 1
Is composed of a stationary blade 1a and a rotor blade (moving blade) 1b. Compressor 1
A plurality of flaps 3, ... Are rotatably provided on the outer peripheral portion of the fixed side nose cone 2 arranged at the air inlet 1a at the front of the flap 3 through a swing lever 3a connected to the inside thereof. Are arranged side by side in the circumferential direction. Here, the swing lever 3a is pin-coupled to the nose cone 2 at the substantially center,
The rear half is connected to the flap 3 and the front end is pin-connected to one end of a link bar 4b described later. Further, a flap tilt angle adjusting means 4 for adjusting a tilt angle θ of the flap 3 with respect to the compressor rotation axis is connected to each flap 3.

The flap inclination angle adjusting means 4 is, for example,
A plurality of actuators 4a having a servo mechanism operated by hydraulic pressure or air pressure are provided at substantially the center of the nose cone 2 supported by brackets (not shown), and a synchronizing ring 2a is provided on the output shafts of these actuators 4a. The link bar 4b is connected to the other end of the link bar 4b. Each of the actuators 4a is controlled while being synchronized with a sensor such as a pressure gauge or a flow meter arranged in the air passage of the compressor 1. The synchronizing ring 2a is interposed between the output shaft of the actuator 4a and the link bar 4b, even if the output shaft of the actuator is controlled to move in synchronization with each other. Depending on the cause, the advancing or retreating speed of each output shaft may be different, and in this case,
There is a risk that the flaps 3 cannot be opened and closed as desired. This is because each link bar is moved at the same speed so as to eliminate such a problem. That is, the plurality of flaps 3 function as a shield member that shields the hub side of the center of the air inlet, and changes the shield area of the air inlet according to the amount of inflow air of the compressor.

Next, the operation of the compressor will be described. FIG. 4 shows the characteristics of the compressor described above. Similar to FIG. 1, the vertical axis represents pressure and the horizontal axis represents air flow rate.
The throttle amount by the throttle portion on the air outflow side (not shown) is small,
When air of a predetermined value or more is flowing by the compressor, each flap 3 is in an open state as shown in FIG. 1 and does not block the center of the air inlet.

When the throttle amount on the air outflow side increases and the flow rate of air flowing into the compressor falls below a certain value, a detection is made by a sensor such as a pressure gauge provided in the air passage of the compressor. Actuator 4 based on signal
a is actuated, and the inclination angle θ of the flap 3 is controlled to widen. The inclination angle θ is controlled to increase as the air flow rate of the compressor decreases.

Therefore, as described above, when the air flow rate becomes a certain value or less in the related art, a stall region is created at the rotor blade tip and a rotating stall tends to occur.
Here, as indicated by the hatched line X in FIG. 2, the hub side at the center of the air passage of the compressor is shielded by the flap 3 to form a stable stall region. The hatched portion in FIG. 3 indicates the stall region of the cross section of the compressor air passage when the air flow rate is H, I, or J.

In this way, the inflowing air is biased toward the fan case side outside the air passage of the compressor, so that even if the air flow rate is reduced to a certain value or less, the rotor blade tip side is sufficient. Air will be supplied, and eventually a rotating stall can be avoided. Then, when the untimely low flow rate passes, the flap 3 is again opened as shown in FIG. 1 based on the detection signal from the sensor arranged in the air passage, and the normal nose cone shape is obtained. To form.

The compressor of the present invention is not limited to the above-described embodiment, but a shielding member for shielding the central side of the air inlet, a mounting structure of the flap 3, a structure of the flap inclination angle adjusting means 4, etc. The specific configuration can be appropriately changed in implementation. For example, the shielding member has a plurality of swing levers 3a, one end of which is pin-connected to the outer circumference of the nose cone.
Although the flaps 3 are connected discretely to each other, the flaps 3 are discretely configured, but the present invention is not limited to this, and the inclined area can be widened without forming a gap (for example, a configuration like a diaphragm of a camera) , The aperture of the camera, on the contrary, expands or narrows the area of the hole on the center side). Further, although the flap tilt angle adjusting means 4 is composed of the actuator 4a, the invention is not limited to this, and a stepping motor may be used.

[0017]

According to the first aspect of the present invention, even when the inflowing air amount decreases below a certain value, the central hub side of the air inlet is shielded by the shielding member, and the outer case side is sufficiently protected. It is possible to secure a sufficient air flow rate and prevent rotating stalls. As a result, stable operation at a low flow rate becomes possible.

According to the second aspect of the present invention, when each flap is closed (when it functions as a shielding member), the central portion of the air passage is shielded while the inflowing air passage resistance is reduced as much as possible. Further, when the flap is opened, it becomes an extension portion along the axial direction of the nose cone, so that the air passage resistance can be reduced even in this case.

According to the third aspect of the present invention, since the flap inclination angle adjusting means for changing the inclination angles of the plurality of flaps according to the amount of inflowing air is provided, the compressor is operated with the maximum performance. be able to. Further, by controlling the plurality of flaps independently of each other, the deviation of the inflowing air can be corrected, which is also effective for the rotating stall due to the inlet distortion.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the operation of the same embodiment.

FIG. 3 is a diagram showing characteristics of the same embodiment.

FIG. 4 is a diagram showing characteristics of a conventional compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 compressor 1a stationary blade 1b rotor blade 2 nose cone 3 flap (shielding member) 4 flap inclination angle adjusting means 4a actuator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Kurosaki Inventor Masahiro Kurosaki 229 Tonogaya, Mizuho-cho, Nishitama-gun, Tokyo Ishi Kawashima Harima Heavy Industries Ltd. Mizuho Plant Co., Ltd.

Claims (3)

[Claims] 1. A shielding member (3) for shielding the central hub side of an air inlet (1a) is provided so that the shielding area of an air passage can be varied, and the shielding area by the shielding member is adjusted according to the amount of inflowing air. A compressor characterized by being controlled by the following. 2. The compressor according to claim 1, wherein the shielding member is composed of a plurality of flaps, one end of which is rotatably connected to the nose cone (2) of the air inlet port and which are arranged side by side in the circumferential direction. Compressor characterized by being. 3. The compressor according to claim 2, further comprising flap tilt angle adjusting means (4) for changing tilt angles of the plurality of flaps according to an amount of inflowing air.