JP3110258B2 - Surge detector with asymmetric centrifugal compressor diffuser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a gas turbine engine,
The present invention relates to a surge detection device using an asymmetric centrifugal compressor diffuser for detecting a surge such as a surge.

[0002]

2. Description of the Related Art A conventional surge detection system will be described with reference to FIGS. FIG. 5 is a cross-sectional view of the turbojet engine, and FIG. 6 is a BB cross-sectional view thereof. 1 on both sides
Reference numeral 4 denotes a rotating shaft, around which a centrifugal compressor impeller 8 is provided. The compressed gas passes through a diffuser 11 and is guided to a main pressure chamber 4 and a combustor 5, where it is guided to a turbine nozzle 6 and a rotor 7. It has a structure that can be inserted. In the conventional surge detection method, in an engine having such a structure, a pressure sensor 13 is attached to the main pressure chamber 4, and a sudden decrease in pressure in the pressure chamber 4 is monitored to detect a surge. However, detection by this method is usually detection of a surge, not detection of a precursor of a surge. In the case of a large axial flow type compressor, since the pressure in the main pressure chamber starts to fluctuate slightly immediately before the surge, there are some which detect and perform surge avoidance control.

[0003]

In the acceleration control of a gas turbine engine, avoiding a surge is an important problem. In the case of the gas turbine engine using the above-described centrifugal compressor, monitoring of the pressure in the main pressure chamber 4 of the related art hardly indicates the occurrence of a surge, and it is virtually impossible to distinguish it from noise. For this reason, it is difficult to predict and control the surge of the centrifugal compressor in the conventional method, and it has been the mainstream that an acceleration schedule with a margin is set in advance and the surge is avoided in an open loop.

However, in this method, since the characteristics of the engine change due to some failure or the like and the surge characteristics change, the control becomes impossible. Therefore, the surge avoidance control which detects the occurrence of the surge and does not deteriorate it further. Although this is made possible by the use of electronic control, there is a problem that the surge enters at least once.

In addition, the efficiency of a centrifugal compressor is generally higher near the surge line, and a large margin for surge reduces the performance of the entire engine (fuel efficiency deteriorates).

[0006]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides a centrifugal compressor diffuser in which a surge-prone portion is provided in a part of a diffuser so that a precursor of a surge can be detected in advance. Diffuser. The flow of the asymmetrical portion is led to a separate chamber, the sub-pressure chamber, and a differential pressure sensor is provided between the sub-pressure chamber and the main pressure chamber to monitor pressure fluctuation intensively.

[0007] That is, the present invention communicates with an asymmetric diffuser formed by extending at least one channel of a centrifugal compressor diffuser of a gas turbine engine to be wider than a normal channel, and with an extended channel of the asymmetric diffuser. A sub-pressure chamber, a pipe connecting the sub-pressure chamber to the main pressure chamber, and a differential pressure sensor provided in the middle of the pipe are provided, and are generated between the sub-pressure chamber and the main pressure chamber. Provided is a surge detector using an asymmetric centrifugal compressor diffuser, which detects a pressure fluctuation by the differential pressure sensor and detects in advance the occurrence of a surge pressure.

[0008]

According to the present invention, the asymmetric diffuser has a wider channel than the normal channel and an extended channel provided by such means, and the surge characteristic of this channel is worse than that of the normal channel. Therefore, a surge occurs in the normal channel, and the pressure in the sub-pressure chamber first decreases before the pressure in the main pressure chamber decreases. At this time, the pressure difference between the sub-pressure chamber and the main pressure chamber is detected by the differential pressure sensor, so that the occurrence of a surge should be avoided in advance by controlling the engine acceleration while constantly monitoring the value of the differential pressure sensor. Can be. It should be noted that the pressure fluctuation in the sub-pressure chamber is asymmetric, and the number of the extension channels is small. Usually, the extension channel is set to 5% or less of the main pressure chamber. At the same time, the occurrence of a surge can be detected in advance.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows a configuration of a detecting device using an asymmetric centrifugal compressor diffuser according to one embodiment of the present invention, and is shown in a cross-sectional view of a turbojet engine. FIG. 2 is a sectional view taken along line AA in FIG. In both figures, 1 is an asymmetric diffuser having a channel 9 extending from a normal channel 10, and 2 is a sub-pressure chamber provided partially above the main pressure chamber 4, as shown in FIG. The channel 10 is partially provided so as to protrude from the main pressure chamber 4 so as to guide this flow path through an extension channel 9 which is an extension of the channel 10. The sub-pressure chamber 2 is provided to extend the duration of occurrence of surge to a measurable extent. The sub-pressure chamber 2 has a capacity approximately equal to the ratio of the asymmetric portion and about 5% of the main pressure chamber 4. Reference numeral 3 denotes a differential pressure sensor provided between the pipes 20 communicating the sub-pressure chamber 2 and the main pressure chamber 4, 5 denotes a combustion chamber, 6 denotes a turbine nozzle, 7 denotes a turbine rotor, 8 denotes a centrifugal compressor impeller, 14 Is a rotation axis.

Therefore, the features of the present invention are the asymmetric centrifugal compressor 1, the auxiliary pressure chamber 2, the differential pressure sensor 3, the extension channel 9, and the pipe 20.

FIG. 3 is a system block diagram of the detection device and the engine. The fluid 21 passes through the centrifugal compressor impeller 8 and
It flows into the main pressure chamber 4 through the channel 10 of the diffuser 1. Part of the fluid 21 enters the sub-pressure chamber 2 through the extension channel 9 and is guided to the main pressure chamber 4. The pressure difference between the sub-pressure chamber 2 and the main pressure chamber 4 is detected by a differential pressure sensor 3 provided in the middle of the pipe 20 therebetween, and transmitted to the control device 31 to avoid the surge before the surge occurs. Operation control is performed. The fluid that has entered the main pressure chamber 4 is guided to a combustor 5 and burns, and is injected from a turbine nozzle 6 to a turbine rotor 7.
It is led to. Therefore, the dotted line portion indicated by 30,
That is, the extension channel 9, the auxiliary pressure chamber 2, and the differential pressure sensor 3 represent the characteristic portions of the present invention.

The operating characteristics of a turbojet engine using a centrifugal compressor are characterized by a centrifugal compressor characteristic map shown in FIG. FIG. 4 shows the relationship between the flow rate and the pressure ratio.
1 is a steady operation line, 22 is an asymmetrical part surge line, 2
3 is a surge line. Numeral 24 denotes an acceleration line, numeral 25 denotes surge detection when the acceleration line 24 exceeds the asymmetrical part surge line, numeral 26 denotes a constant rotation line (95%), and numeral 27 denotes a line of 100%.

To increase the output of the engine, FIG.
In the above, the rotational speed of the rotating body in which the centrifugal compressor impeller 8 and the high-pressure turbine rotor 7 are connected must be increased. At this time, the engine leaves the steady operation line 21 shown in FIG. On the other hand, as a characteristic of a centrifugal compressor, when a strong acceleration is performed, an abnormal phenomenon called a surge occurs, so that not only normal operation cannot be performed but also there is a risk of destroying the engine. this is,
It is characterized by a surge line 23 (dashed line) in FIG. 4, and a surge occurs when the line 23 is exceeded.

Therefore, when the engine is operated, the acceleration must be controlled so as not to exceed the surge line 23. However, it is very difficult to detect a precursor of a surge. In practice, a surge line is predicted in advance, and acceleration control is performed with a large margin.

In the present invention, as shown in FIG. 2, one or several of the channels 10 (usually of this shape) of the centrifugal compressor diffuser 1 are extended, and the extended channel 9 is used as an auxiliary pressure chamber. 2 and then return to the main pressure chamber 4.

The special extension channel section 9 has a larger area expansion rate than the normal section channel 10, and has a better performance in a steady state than the normal section channel 10, but has a deteriorated surge characteristic. (Dash-dotted line) of the asymmetrical part surge line 22. Therefore, the channel 10 of the normal part enters a surge (exceeds the surge line 23) before the pressure of the main pressure chamber 4 drops and the auxiliary pressure chamber 2, the pressure difference is detected by the differential pressure sensor 13 and the surge 25
Can be detected in advance.

Therefore, by performing acceleration control while constantly monitoring the differential pressure sensor value, it is possible to perform maximum acceleration while avoiding a surge. Since the surge in the asymmetric portion has a small number of channels in the asymmetric portion (designed to be 5% or less), the influence is small compared to the case where the surge enters the whole at the same time, and there is almost no problem.

In the above embodiment, the surge detector indicated by reference numeral 30 in the block diagram of FIG. 3 has been described as applied to a turbojet engine as shown in FIGS. 1 and 2. However, the present invention is not limited to this. However, the detailed description is omitted because the structure of the embodiment is the same, but the turbojet engine and the gas generator unit have the same structure, that is, the turbojet engine, the turbofan engine, the gas turbine engine, the air The same applies to the source gas turbine engine,
It is effective.

[0019]

As described above in detail, in the present invention, an extension channel is provided in a part of the channel of the centrifugal compressor diffuser of the gas turbine engine to form an asymmetric diffuser, and the auxiliary channel communicating with the extension channel is provided. A pressure chamber, a pipe connecting the sub-pressure chamber and the main pressure chamber are provided, and a differential pressure sensor is provided in this pipe to detect a pressure difference to detect in advance the occurrence of surge pressure. Such an effect is provided.

(1) A precursor of a surge can be measured before a mainstream surge occurs.

(2) Therefore, by monitoring this measured value, it is possible to avoid a surge and to accelerate.

(3) Since surge is predicted by measurement, surge avoidance control can respond to changes in engine characteristics and operating environment.

(4) Since the acceleration can be achieved just before the surge line, the response performance of the engine is improved.

(5) Conversely, since the acceleration margin can be reduced, the operating line can be made closer to the surge line, and the fuel consumption rate of the engine can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an asymmetric centrifugal compressor according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a block diagram of a surge detector using a diffuser of the asymmetric centrifugal compressor according to one embodiment of the present invention.

FIG. 4 is a diagram illustrating a general relationship between a flow rate and a pressure ratio of a centrifugal compressor in a gas turbine engine.

FIG. 5 is a cross-sectional view of a conventional centrifugal compressor diffuser.

FIG. 6 is a sectional view taken along line BB in FIG.

[Explanation of symbols]

 Reference Signs List 1 asymmetric diffuser 2 auxiliary pressure chamber 3 differential pressure sensor 4 main pressure chamber 5 combustion chamber 6 turbine nozzle 7 turbine rotor 8 centrifugal compressor impeller 9 extension channel 10 channel

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02C 7/00 F02C 9/00 F04D 27/02

Claims (1)

(57) [Claims] 1. An asymmetric diffuser, wherein at least one channel of a centrifugal compressor diffuser of a gas turbine engine is extended and extended more than a normal channel, and a sub-pressure chamber communicating with an extended channel of the asymmetric diffuser. A pipe connecting the sub-pressure chamber to the main pressure chamber, and a differential pressure sensor provided in the middle of the pipe, wherein the pressure fluctuation generated between the sub-pressure chamber and the main pressure chamber is A surge detector using an asymmetric centrifugal compressor diffuser, which detects a surge pressure in advance by detecting with a differential pressure sensor.