KR100402960B1 - Control method of gas turbine engine - Google Patents

Abstract

A control method of a gas turbine engine is disclosed.

The control method of a gas turbine engine according to the present invention, (a) the physical maximum rotational speed that can be operated by using the constant pressure of the compressor inlet according to the total temperature at the compressor inlet of the engine and the flying speed of the target to which the engine is mounted Setting up; (b) establishing a relationship between the flight speed of the object on which the engine is mounted and the static pressure at the compressor inlet of the engine; (c) establishing a relationship between the physical maximum speed and the corrected maximum speed; (d) setting the corrected maximum speed according to the total temperature at the compressor inlet and the corrected maximum speed according to the static pressure at the compressor inlet; (e) selecting a smaller value among the corrected maximum rotational speeds set in step (d) and converting them into physical maximum rotational speeds from the relationship established in step (c); And (f) inputting the converted physical maximum speed into an engine.

Description

Control method of gas turbine engine

The present invention relates to a gas turbine engine, and more particularly, to a control method of a gas turbine engine for maintaining the same thrust.

In general, an engine refers to a mechanical device that receives thermal energy and converts it into mechanical energy, and typically includes an external combustion engine, an internal combustion engine, a gas turbine engine, a rocket engine, and a nuclear engine.

Here, the gas turbine engine 10 is a kind of rotary internal combustion engine shown in FIG. 1 and expands a combustion gas of high temperature and high pressure, and rotates the turbine 13 to obtain rotational force.

In other words, the air whose pressure rises due to dynamic pressure is increased again by the compressor 11 and made into a hot gas of about 800 to 1200 ° C. in the combustion chamber 12, and then until the required pressure ratio to obtain the required output of the compressor 11. It expands in the turbine 13 and blows gas at high speed through the jet nozzle 14 at the remaining pressure to obtain propulsion.

The gas turbine engine 10 has a simpler structure, lighter weight, easier handling, and produces large horsepower energy than a reciprocating internal combustion engine or steam turbine, and enables the use of low-grade fuel and less trouble or vibration. There is this. Therefore, it is mainly used for power plants, locomotives, ships and aircrafts.

Typically, the maximum rotational speed of the gas turbine engine is used as the main variable to control the thrust of the engine.

As the maximum rotational speed of the gas turbine engine increases, the temperature at the turbine inlet rises and the axial load acting on the bearing supporting the rotating portion increases. In addition, the temperature of the bearing due to frictional heat during rotation is increased. Therefore, the maximum rotational speed is limited by the above factors. In addition, the maximum rotation speed is limited by the structural limitation of the engine rotor. Here, the maximum rotational speed means the physical maximum rotational speed.

2 shows the physical maximum rotational speed for the above limiting factors. In addition, in order to set the physical maximum rotational speed, the relationship between the total temperature and the physical maximum rotational speed conventionally used is shown.

Hereinafter, a detailed description will be given with reference to the drawings.

First, A and B diagrams show the physical maximum rotational speeds according to the total temperature of the air at the compressor inlet when the flight speeds of the engine-mounted targets are M1 and M4, respectively. In addition, each diagram has the condition of the same turbine inlet temperature.

The C diagram, the D diagram, the E diagram, and the F diagram show the physical rotation speeds according to the entire air temperatures when the flight speeds of the engine-mounted targets are M1, M2, M3, and M4, respectively. Each diagram also has the same axial conditions acting on the bearing.

In addition, the G diagram, the H diagram, the I diagram, and the J diagram show the physical maximum rotational speeds according to all the temperatures of the air, when the flying speeds of the engine-mounted targets are M1, M2, M3, and M4, respectively. Each diagram also has the same bearing temperature conditions.

M1, M2, M3, and M4 are Mach numbers 0.6, 0.7, 0.8, and 0.85, respectively. Here, the Mach number refers to the speed ratio of the flight speed of the target on which the engine is mounted.

Finally, the K diagram shows the physical maximum rotational speed in accordance with the structural limit caused by the action of centrifugal force during rotation of the engine rotor.

Conventionally, a method of setting a physical maximum rotational speed of a gas turbine engine based on the total temperature at the compressor inlet of the engine has been used. Therefore, on the basis of the L diagram of FIG. 2, which satisfies each of the above limiting factors, the physical maximum rotation speed according to the total temperature of the compressor inlet was set.

By the way, the conventional control method is that when the static temperature and static pressure of the air outside the engine are constant, when the flying speed of the target on which the engine is mounted decreases, the engine There is a problem that the maximum thrust of does not remain the same.

The problem is described with reference to FIG. 2 as follows.

First, when the flight speed of the target on which the engine is mounted decreases, the total temperature of air at the compressor inlet of the engine is lowered. This can generally be seen from the following equation.

When the total temperature of the air in the compressor of the engine is lowered due to the decrease in the flying speed of the engine-mounted object as shown in the above equation, as shown in the figure, the value of the maximum rotation speed is set small. The smaller the maximum speed, the less the maximum thrust the engine can produce. When the maximum thrust of the engine is reduced, the acceleration of the target on which the engine is mounted decreases in acceleration, making smooth maneuvering difficult. That is, as the flight speed of the target on which the engine is mounted decreases, the maximum thrust that the engine can produce decreases. Accordingly, the acceleration force of the target on which the engine is mounted decreases, thereby increasing the time for speed recovery at a high speed again.

This phenomenon is repeated until the entire temperature approaches the constant temperature. And this is solved at the point where the maximum rotational speed of the engine decreases, and the reduced thrust according to the reduced maximum rotational speed and the movement speed according to the mass of the object on which the engine is mounted are balanced. As a result, the thrust cannot be kept the same.

In order to solve the problem, a method of directly measuring the thrust of the engine or measuring the constant temperature instead of the total temperature of the air at the compressor inlet may be used. Alternatively, a method of calculating the flight speed of the target on which the engine is mounted by measuring the total pressure and the static pressure of air at the compressor inlet may be used.

However, these methods also, the measurement of the thrust and the measurement of the static temperature is impossible with the existing sensor, the measurement of the voltage force also has a lot of restrictions in the installation of the pressure sensor.

The present invention is to solve the above problems, by setting the relationship between the static pressure of the compressor inlet and the physical maximum rotational speed according to the flight speed of the target to which the engine is mounted, as well as the full temperature at the compressor inlet, input to the engine, It is an object of the present invention to provide an improved method of controlling a gas turbine engine that can maintain a constant maximum thrust.

1 is a cross-sectional view showing a conventional gas turbine engine,

2 is a graph showing the relationship between the total temperature and the physical maximum rotation speed conventionally used to set the physical maximum rotation speed,

FIG. 3 is a graph showing the relationship between the full temperature and the engine's flight speed and the physical maximum speed according to the present invention;

4 is a graph showing the relationship between the total temperature and the corrected maximum rotation speed according to the present invention;

5 is a graph showing the relationship between the static pressure and the corrected maximum rotation speed according to the present invention.

<Description of Symbols for Main Parts of Drawings>

Compressor 12. Combustion chamber

13.Turbine 14.Jet Nozzle

M1 .. Mach Numbers 0.6 M2 .. Mach Numbers 0.7

M3 Mach Numbers 0.8 M4 Mach Numbers 0.85

Control method of the gas turbine engine according to the present invention for achieving the above object,

(a) setting a maximum physical rotational speed that can be operated by using the constant pressure of the compressor inlet according to the total temperature at the compressor inlet of the engine and the flying speed of the target to which the engine is mounted;

(b) establishing a relationship between the flight speed of the object on which the engine is mounted and the static pressure at the compressor inlet of the engine;

(c) establishing a relationship between the physical maximum speed and the corrected maximum speed;

(d) setting the corrected maximum speed according to the total temperature at the compressor inlet and the corrected maximum speed according to the static pressure at the compressor inlet;

(e) selecting a smaller value among the corrected maximum rotational speeds set in step (d) and converting them into physical maximum rotational speeds from the relationship established in step (c); And

(f) inputting the converted physical maximum rotational speed into an engine.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 illustrates the relationship between the total temperature of air at the compressor inlet, the flight speed of the engine-mounted object, and the physical maximum rotation speed according to the embodiment of the present invention.

Referring to the drawings, the M diagram, the N diagram, the O diagram, and the P diagram, respectively, indicate the physical maximum rotational speeds depending on the total temperature of the air when the flying speeds of the engine-mounted targets are M1, M2, M3, and M4.

The diagrams in this figure simulate the engine condition using a gas turbine engine performance analysis program using the engine component test data. Is obtained.

In general, the physical maximum rotational speed increases as the total temperature of the air increases, and the physical maximum rotational speed also increases as the flight speed of the target on which the engine is mounted decreases.

Referring to FIG. 3, the control method according to the present invention will be described with reference to the following.

In the drawing, when the constant temperature and the constant pressure of the air outside the engine are constant, if the flight speed of the target equipped with the engine flowing into the engine compressor inlet due to external factors decreases from M4 to M3, When the static pressure decreases, the total temperature of the air at the compressor inlet is lowered due to a decrease in the flight speed of the engine-mounted object (see Equation 1).

According to the conventional control method, since only the entire temperature is used, the point a is changed to the point b along the diagram of the flight speed of the target equipped with the same engine in the drawing, that is, the P diagram. Therefore, the physical maximum rotation speed is reduced.

However, in the present invention, by introducing the static pressure of the compressor inlet of the engine according to the flight speed of the target to which the engine is mounted in addition to the full temperature, the physical maximum rotation speed according to the full temperature and the static pressure is set. Therefore, the physical maximum rotational speed at point c in the figure keeps the maximum thrust that the engine can produce.

On the other hand, Figure 3 shows a simulation result, in order to set the maximum physical speed, the air temperature and the value of the flight speed of the target engine is to be given.

However, in actual engine operation, the total temperature of the air and the flight speed of the target on which the engine is mounted are values to be measured by a sensor. As mentioned in the prior art, the full temperature can be measured in the actual engine. However, there are many limitations to the measurement of the flight speed of an engine mounted object. In addition, given the limited programming capacity of the engine controller, the logic for setting the maximum rpm of the engine needs to be handled simply and simplified.

Therefore, on the basis of a point that satisfies the limiting factor of the turbine inlet temperature in the expected engine operating conditions, the physical maximum rotation speed according to the change of the total temperature is obtained.

Typically, the turbine inlet temperature is determined by the air temperature at the combustor inlet of the engine, i.e., the compressor outlet, and the amount of fuel, wherein the air temperature at the compressor outlet uses the pressure ratio of the compressor and the total temperature of the compressor inlet at a given compressor efficiency. The pressure ratio of the compressor is determined according to the physical rotation speed. Therefore, since the turbine inlet temperature of the engine is closely related to the total temperature and the physical rotation speed, the limiting factor of the turbine inlet temperature must be satisfied for the actual operation of the engine.

Substituting the maximum physical speed obtained as described above into Equation 2 to be described later, it is possible to obtain the relationship between the corrected maximum speed according to the entire temperature.

4 is a graph showing the relationship between the total temperature obtained through such a process and the corrected maximum rotation speed.

In the above equation, the reference temperature is an absolute temperature of 288.15K as the temperature at 15 ° C.

In the figure, the Q diagram is the connection of the respective data. The best representation of the data is the R diagram. Therefore, the corrected maximum rotation speed for the entire temperature, such as the R diagram, can be represented by the linear function.

And, according to the flight speed of the target on which the engine is mounted, it is possible to obtain a physical maximum rotation speed that satisfies the limiting factor during the celebration of the engine.

Typically, the axial load of the engine is the load that the bearing must withstand by the load generated by the pressure difference in the engine inlet, compressor, and turbine, which is disposed along the axis of the engine. Since the load is generated by the pressure, it is related to the pressure ratio determined by the total pressure of the engine and the total pressure of the engine inlet generated according to the flying speed of the vehicle. Therefore, congratulatory limitations of the engine must be met for actual engine operation.

When the physical maximum rotation speed is modified to the corrected maximum rotation speed, a constant relationship with the static pressure is shown, which is illustrated in FIG. 5.

Here, the static pressure is a value that can be measured directly from the sensor.

In the figure, the S diagram shows the connection of the respective data, and the T diagram is the best representative function of the data. Therefore, the corrected maximum rotation speed for the static pressure from the T diagram can be expressed as a quadratic function.

As such, the control logic can be simplified by expressing the relationship between the total temperature and the corrected maximum rotation speed and the relationship between the static pressure and the corrected maximum rotation speed, respectively.

4 and 5, the corrected maximum rotation speed according to the total temperature of the air and the corrected maximum rotation speed according to the static pressure are respectively obtained, and the smaller corrected maximum rotation speed of the two values is obtained. Convert to the maximum physical rotation speed using the relationship of Equation 2. The reason for choosing a smaller value is to ensure engine stability.

The same maximum thrust is maintained by inputting the converted physical maximum rotation speed to the control of the engine.

The control method of the gas turbine engine according to the present invention has the following effects.

First, as the flight speed of the target on which the engine is mounted decreases, even if the total temperature of the air at the compressor inlet decreases, by setting the physical maximum rotational speed of the engine according to the present invention, the engine maximum thrust is kept the same. Can accelerate.

Second, by applying the full temperature and static pressure at the compressor inlet obtained by direct measurement with the sensor, no additional sensor is required.

Third, the control logic can be simplified by expressing the relationship between the total temperature and the corrected maximum rotation speed and the relationship between the static pressure and the corrected maximum rotation speed, respectively.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary and will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (1)

(a) setting a maximum physical rotational speed that can be operated by using the constant pressure of the compressor inlet according to the total temperature at the compressor inlet of the engine and the flying speed of the target to which the engine is mounted; (b) establishing a relationship between the flight speed of the object on which the engine is mounted and the static pressure at the compressor inlet of the engine; (c) establishing a relationship between the physical maximum speed and the corrected maximum speed; (d) setting the corrected maximum speed according to the total temperature at the compressor inlet and the corrected maximum speed according to the static pressure at the compressor inlet; (e) selecting a smaller value among the corrected maximum rotational speeds set in step (d) and converting them into physical maximum rotational speeds from the relationship established in step (c); And (f) inputting the converted physical maximum speed into an engine; Gas turbine engine control method comprising a.