JP2002070585A - Surge avoiding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surge avoiding system preventing sequential surging of a jet engine beforehand. SOLUTION: Detectable state parameters (for example, rotation speed, pressure, etc.), of the jet engine 10 are detected by a sensor system 11 and transmitted to a surge avoiding system 12. An observer constructed in the surge avoiding system estimates the state parameters undetectable by the sensor system based on the state quantity and fuel quantity detected by the sensor system and a compressor operation state determination part constructed in the surge avoiding system grasps a present operation point based on the preset compressor characteristics. When there is a possibility of entering into a surge region, the opening of a throttle valve 13 is adjusted by a feedback signal obtained by multiplying a gain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surge avoidance system, and more particularly to a surge avoidance system for preventing continuous surging of a jet engine.

[0002]

2. Description of the Related Art A jet engine injects and burns fuel into intake air compressed by a compressor to produce a compressed high-temperature gas, expands the compressed high-temperature gas, rotates a turbine that drives the compressor, and ejects the gas backward. The thrust is obtained. Therefore, it is important to avoid compressor surging in order to maintain stable operation.However, in a conventional jet engine control device, when a sudden decrease in compressor outlet pressure is detected, the amount of injected fuel is reduced. By reducing the number, the occurrence of continuous surge is prevented.

[0003]

However, when a sudden decrease in the compressor outlet pressure is detected, since a rotating stall has already occurred in a part of the compressor blades, a continuous surge occurs even if the amount of injected fuel is reduced. There is a risk that it will. The present invention has been made in consideration of the above problems, and has as its object to provide a surge avoidance system that can prevent continuous surging of a jet engine.

[0004]

A surge avoidance system according to the present invention includes an observer for estimating at least an undetectable state variable of a jet engine based on an operation amount of the jet engine and a detectable variable of the jet engine. Operating condition determining means for determining whether the operating point of the compressor of the jet engine is approaching the surge region based on the state variable estimated by the observer; and operating condition determining means for determining whether the operating point of the compressor is approaching the surge region. A fuel reducing means for reducing the amount of fuel to be supplied to the jet engine when it is determined that the fuel injection is performed.

According to the present invention, a state variable including an undetectable state variable is estimated by an observer, and an operating condition of the compressor is determined based on the estimated state variable. Is reduced, and it is prevented from entering the surge region.

[0006]

FIG. 1 is a block diagram of a surge avoidance system according to the present invention. The operating state of a jet engine 10 is detected by a sensor system 11 including a rotational speed sensor, a pressure sensor, and the like. The result is transmitted to a surge avoidance system 12 composed of a digital computer.

[0007] The surge avoidance system 12 determines the current operating state of the compressor 101 of the jet engine 10 and controls the opening of the throttle valve 13 to prevent the compressor 101 from entering the surge region. In the jet engine 10, air sucked from the intake port 100 is compressed by the compressor 101 and supplied to the combustor 102.

The high-temperature gas generated by the combustion of the fuel injected from the fuel injection holes 104 in the combustor 102 imparts a rotational force to the turbine 103 and the nozzle 105
To generate thrust. In addition, the throttle valve 1
Reference numeral 3 is provided between the fuel tank 14 and the fuel injection hole 104 to adjust the amount of fuel injected from the fuel injection hole 104.

The torque generated by the turbine 103 is transmitted to the compressor 101 by a directly connected shaft, and drives the compressor 101. The equation of motion of the rotating body of the jet engine having the above configuration is represented by [Equation 1].

[0010]

(Equation 1)

Here, the turbine output power LT is represented by the following equation (2).

[0012]

(Equation 2)

[0013] The compressor absorption power LC is given by
It is represented by

[0014]

(Equation 3)

The dynamic characteristic equation of the compressor is expressed by [Equation 4].

[0016]

(Equation 4)

Further, the state equation of the air compressed by the compressor is given by [Equation 5].

[0018]

(Equation 5)

The above five equations are linearized around a steady state value, and a state variable is defined by [Equation 6].

[0020]

(Equation 6)

Then, the dynamic characteristic of the jet engine is represented by [Equation 7]. FIG. 2 is a state variable diagram of the jet engine.

[0022]

(Equation 7)

As can be seen from the above, among the state variables that determine the dynamic characteristics of the jet engine, some state variables that cannot be actually detected are included, but if these state variables can be detected, the swirl generated in a part of the compressor The occurrence of stall can be detected early. Therefore, all state variables including state variables that cannot be detected using the observer are estimated based on the state variables that can be detected and the dynamic characteristic equation of the jet engine represented by [Equation 6].

For example, the dynamic characteristic equation of the observer can be expressed by [Equation 8].

[0025]

(Equation 8)

By feeding back all the state variables estimated by the observer via the compressor operating condition determination unit and a predetermined gain, it is possible to prevent the occurrence of a continuous surge. FIG. 3 is a state variable diagram of the jet engine, the observer, the compressor operation status determination unit, and the gain. The observer 31, the compressor operation status determination unit 32, and the gain 33 are added to the jet engine 30.

Note that the observer 31, the compressor operating condition determination unit 32, and the gain 33 are constructed in the surge avoidance system 12 by software. That is, the compressor operation status determination unit 32, for example, the gas flow rate on the horizontal axis,
The characteristic curve of the compressor with the compression ratio taken on the vertical axis is stored, and the current operating point is monitored by the characteristic curve based on the state variable estimated by the observer.

Then, when there is a possibility that a continuous surge may occur when approaching the surge line, feedback is provided via a gain to reduce the fuel amount. As a result of reducing the fuel amount, when the operating point of the compressor moves away from the surge line, the output of the jet engine can be maintained by restoring the fuel amount.

[0029]

According to the surge avoidance system according to the present invention, the operating state of the compressor can be accurately grasped by estimating the undetectable state variable by the observer, and the occurrence of the continuous surge can be reliably achieved. This can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a surge avoidance system according to the present invention.

FIG. 2 shows dynamic characteristics of a jet engine.

FIG. 3 is a state variable diagram of a jet engine, an observer, a compressor operation status determination unit, and a gain.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Jet engine 100 ... Intake port 101 ... Compressor 102 ... Combustor 103 ... Turbine 104 ... Fuel injection hole 105 ... Nozzle 11 ... Sensor system 12 ... Surge avoidance system 13 ... Throttle valve 14 ... Fuel tank

Claims (1)

[Claims] 1. An observer for estimating at least an undetectable state variable of the jet engine based on an operation amount of the jet engine and a detectable state variable of the jet engine, and based on a state variable estimated by the observer. Operating condition determining means for determining whether the operating point of the compressor of the jet engine is approaching the surge region, and when the operating condition determining means determines that the operating point of the compressor is approaching the surge region. A surge avoidance system including a fuel reducing means for reducing an amount of fuel supplied to the jet engine.