Overtemperature protection method for regenerative cooling ramjet engine based on flight-engine integrated control

Abstract

The invention belongs to the technical field of scramjet engine control, and particularly discloses a regenerative cooling ramjet engine overtemperature protection method based on flight-engine integrated control, and the overtemperature protection method comprises flight-engine integrated control of an engine overtemperature state and a self-optimization control method of the temperature of the engine. According to the overtemperature protection method, the overtemperature problem of the regenerative cooling ramjet engine can be effectively solved from the angle of flight-engine integrated control, and technical guarantee is provided for normal work of the regenerative cooling ramjet engine.

Description

Technical Field

[0001] The present invention belongs to the technical field of scramjet engine control, and more specifically, relates to a regenerative cooling ramjet engine over-temperature protection technology with the concept of flight-engine integrated control as the core. Background Art

[0002] Scramjet engines are an optimal power unit for hypersonic vehicles. When scramjet engines operate at high Mach numbers, the operating temperature of the combustion chamber is very high due to the increase in the total temperature of the incoming flow and the heat released by engine combustion. Long-term operation of the engine at high temperatures can easily cause wall ablation, increasing the risk of burning the engine. Regenerative cooling is an effective solution for engine thermal protection. The engine wall is cooled by passing cold fuel through the cooling channel on the engine wall. Regenerative cooling thermal protection technology can ensure that scramjet engines can operate reliably for a long time, and is one of the core technologies for developing reusable scramjet engines.

[0003] In recent years, a lot of research has been carried out on the over-temperature protection methods of regeneratively cooled ramjet engines at home and abroad. The current over-temperature protection methods of scramjet engines are mainly centered around the engine itself. The current over-temperature protection control method uses the oil temperature in the engine's regenerative cooling channel as the monitoring variable. When the engine temperature exceeds the set temperature threshold, the engine over-temperature protection system starts to work. The main measure currently used is to increase the fuel flow rate, that is, to increase the convective heat transfer intensity, thereby reducing the engine temperature.

[0004] The existing over-temperature protection methods have certain shortcomings, which are mainly reflected in the following aspects: the aircraft and the engine are strongly coupled systems. In many cases, the reason for the engine overheating is that the aircraft has flown to the working boundary of the engine. For example, the aircraft speed is too high, which causes the engine intake heat load to increase and the engine overheats. The existing over-temperature protection control strategy only provides protection from the perspective of the engine, and fails to formulate a protection strategy from the perspective of aircraft-engine integrated control, which will lead to the failure of engine over-temperature protection. Therefore, it is necessary to formulate a new over-temperature protection method for regenerative cooling ramjet engines from the perspective of aircraft-engine integrated control. Summary of the invention

[0005] In view of the defects of the prior art, the present invention provides an over-temperature protection control method suitable for a regenerative cooling ramjet engine with the concept of integrated flight and engine control as the core.

[0006] The specific technical solutions of the present invention are as follows: The over-temperature protection method of the regenerative cooling ramjet engine based on the integrated control of the aircraft and the engine adopts the engine temperature protection strategy based on the integrated control idea of ​​the aircraft and the engine and the temperature self-optimization control method for the engine itself; The engine temperature protection strategy based on the integrated control concept of aircraft and engine means that: the engine temperature control method adopts the method of joint control of aircraft and engine. When the engine temperature exceeds the safety limit, in addition to the engine itself executing control actions, the aircraft must also cooperate with the engine to take corresponding control measures; The temperature self-optimization control for the engine itself means: designing an engine temperature control algorithm for the engine itself, which uses a self-optimization method to quickly adjust the engine temperature to the minimum value within the constraint range.

[0007] As a preferred method, when the engine temperature exceeds the safety boundary, a joint control strategy of the aircraft and the engine is adopted, that is, the aircraft reduces the speed of the aircraft to the safety domain by increasing the drag and the flight angle of attack, thereby reducing the thermal load of the engine. The engine itself adjusts the temperature of the engine body through the temperature control algorithm, and returns to the normal cruising state when the engine temperature is effectively controlled. The temperature safety boundary can be defined as the maximum temperature allowed for the engine to operate, such as 1200K, and the temperature safety boundary is pre-set according to the temperature operating range of the engine.

[0008] As a preferred method, the engine temperature protection strategy based on the aircraft-engine integrated control concept includes the following steps: (1) Monitor the engine temperature status in real time to determine whether the engine temperature is within the safety limit; (2) If the engine temperature exceeds the temperature safety boundary, the aircraft and engine integrated control strategy is adopted. The aircraft reduces the speed of the aircraft by increasing the drag and the flight angle of attack, thereby reducing the heat load of the engine. The engine itself adjusts the engine temperature through the temperature control algorithm. (3) When the engine temperature returns to within the safe range, the aircraft and engine return to normal cruise operating conditions.

[0009] As a preferred method, the temperature self-optimization control method for the engine itself includes designing an extreme value search controller and an engine temperature system: The extreme value search controller calculates the fuel flow control amount according to the real-time temperature feedback from the engine temperature system. After receiving the new control amount, the engine temperature system takes effect and forms a new temperature output. After multiple rounds of control iterations, the self-optimization of the temperature extreme value is completed and the minimum temperature is reached within a certain temperature range.

[0010] As a preferred method, the temperature self-optimization control for the engine itself means that the engine temperature system outputs the real-time temperature of the engine, removes the DC component of the oscillation signal after passing through a high-pass filter, and then adds a sinusoidal signal to demodulate the signal to obtain a demodulated signal ,use The controller calculates the best estimate of the fuel mass flow rate ,in k is an integral gain, s is a complex variable in Laplace transform, and finally through The new fuel control amount is obtained by sinusoidal modulation signal .

[0011] As a preferred method, the temperature self-optimization control for the engine itself includes the following steps: (1) Design the disturbance signal amplitude in the extreme value search controller a , design the angular frequency parameters of the sinusoidal excitation signal in the extreme value search controller ω , the input signal u Add a sinusoidal disturbance to (2) Input signal u Enter the engine temperature system, and the system outputs the real-time temperature signal of the engine; (3) Design of high-pass filter in controller s / ( s + h ), high-pass filter the output temperature signal; s is the complex variable in Laplace transform, h is the filtering frequency; (4) Design the integral gain in the controller k , demodulate the signal and integrate it to get the best estimate of the fuel mass flow rate, and finally add it to the input signal u middle.

[0012] As a preferred method, the design method of the extreme value search controller is: For the disturbance signal amplitude in the extreme value search controller a , its value should make the system output change. a When it increases, the speed of system adjustment increases, which enables the system to converge to the target value neighborhood faster. a The principle of value is: when the system reaches stability, u 30%~50% of the average value; The angular frequency parameter of the sinusoidal excitation signal in the controller is ω , the design value should be greater than the natural frequency of the system; when increasing ω When the system is adjusted, the adjustment speed is improved; For the high pass filter in the controller s / ( s + h ), where h is the filter frequency to remove the oscillation signal before demodulation ρ The DC component of For the integral gain in the controller k The selection of mainly follows the following rules: k When it increases, the adjustment speed of the system increases; if k If the integral gain is too large, the system will be unstable. k The selection of must ensure both the adjustment speed and the system stability, and the most suitable integral gain value should be debugged according to the actual system characteristics.

[0013] The beneficial effects of the present invention compared with the prior art are: The present invention adopts an over-temperature protection scheme that integrates the aircraft and the engine, and designs an extreme value search control method for the temperature, which can effectively control the temperature after the engine overheats, and at the same time adopt an extreme value search algorithm to realize the adaptive adjustment of the temperature to the minimum value. The over-temperature protection method of the regenerative cooling ramjet engine based on the integrated control of the aircraft and the engine effectively solves the over-temperature problem of the engine and can realize the adaptive optimization control of the engine temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a temperature protection flow chart of a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft.

[0015] Figure 2 Block diagram of the self-optimizing control system for the regenerative cooling engine temperature.

[0016] Figure 3 This is the relationship curve between fuel flow and temperature for regenerative cooling engine. DETAILED DESCRIPTION

[0017] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0018] The embodiment provides a regenerative cooling ramjet engine over-temperature protection method based on integrated control of the engine and the flight, adopting an engine temperature protection strategy based on the integrated control idea of ​​the engine and the temperature self-optimization control method for the engine itself; The engine temperature protection strategy based on the integrated control concept of aircraft and engine means that: the engine temperature control method adopts the method of joint control of aircraft and engine. When the engine temperature exceeds the safety limit, in addition to the engine itself executing control actions, the aircraft must also cooperate with the engine to take corresponding control measures; The temperature self-optimization control for the engine itself means: designing an engine temperature control algorithm for the engine itself, which uses a self-optimization method to quickly adjust the engine temperature to the minimum value within the constraint range.

[0019] When the engine temperature exceeds the safety boundary, a joint control strategy of the aircraft and the engine is adopted. That is, the aircraft reduces the speed of the aircraft to the safe domain by increasing the drag by ruddering and increasing the flight angle of attack, thereby reducing the thermal load of the engine. The engine itself adjusts the temperature of the engine body through a temperature control algorithm. When the engine temperature is effectively controlled, it returns to normal cruising working state.

[0020] like Figure 1 As shown, specifically, the engine temperature protection strategy based on the aircraft-engine integrated control concept includes the following steps: (1) Monitor the engine temperature status in real time to determine whether the engine temperature is within the safety limit; (2) If the engine temperature exceeds the temperature safety boundary, the aircraft and engine integrated control strategy is adopted. The aircraft reduces the speed of the aircraft by increasing the drag and the flight angle of attack, thereby reducing the heat load of the engine. The engine itself adjusts the engine temperature through the temperature control algorithm. (3) When the engine temperature returns to within the safe range, the aircraft and engine return to normal cruise operating conditions.

[0021] Specifically, the temperature self-optimization control method for the engine itself includes designing an extreme value search controller and an engine temperature system: The extreme value search controller calculates the fuel flow control amount according to the real-time temperature feedback from the engine temperature system. After receiving the new control amount, the engine temperature system takes effect and forms a new temperature output. After multiple rounds of control iterations, the self-optimization of the temperature extreme value is completed and the minimum temperature is reached within a certain temperature range.

[0022] like Figure 2 Specifically, the temperature self-optimization control for the engine itself means that the engine temperature system outputs the real-time temperature of the engine, removes the DC component of the oscillation signal after passing through a high-pass filter, and then adds a sinusoidal signal to demodulate the signal to obtain a demodulated signal ,use The controller calculates the best estimate of the fuel mass flow rate ,in k is an integral gain, s is a complex variable, and finally through The new fuel control amount is obtained by sinusoidal modulation signal .exist Figure 2 middle, TIndicates the actual operating temperature of the engine. is the fuel mass flow rate To the actual engine temperature T The mapping function of For function The minimum value of is the value of the independent variable when the function reaches its minimum value, It is the engine temperature data value after high-pass filtering.

[0023] Specifically, the temperature self-optimization control for the engine itself includes the following steps: (1) Design the disturbance signal amplitude in the extreme value search controller a , design the angular frequency parameters of the sinusoidal excitation signal in the extreme value search controller ω , the input signal u Add a sinusoidal disturbance to (2) Input signal u Enter the engine temperature system, and the system outputs the real-time temperature signal of the engine; (3) Design of high-pass filter in controller s / ( s + h ), high-pass filter the output temperature signal; s is the complex variable in Laplace transform, h is the filtering frequency; (4) Design the integral gain in the controller k , demodulate the signal and integrate it to get the best estimate of the fuel mass flow rate, and finally add it to the input signal u middle.

[0024] Specifically, the design method of the extreme value search controller is: For the disturbance signal amplitude in the extreme value search controller a , its value should make the system output change. a When it increases, the speed of system adjustment increases, which enables the system to converge to the target value neighborhood faster. a The principle of value is: when the system reaches stability, u 30%~50% of the average value; The angular frequency parameter of the sinusoidal excitation signal in the controller is ω , the design value should be greater than the natural frequency of the system; when increasing ω When the system is adjusted, the adjustment speed is improved; For the high pass filter in the controller s / ( s + h ), where h is the filter frequency to remove the oscillation signal before demodulation ρ The DC component of For the integral gain in the controller k The selection of mainly follows the following rules: k When it increases, the adjustment speed of the system increases; if k If the integral gain is too large, the system will be unstable. k The selection of must ensure both the adjustment speed and the system stability, and the most suitable integral gain value should be debugged according to the actual system characteristics.

[0025] This embodiment provides a specific implementation method of over-temperature protection of a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft, which mainly includes a temperature protection strategy for a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft and a temperature self-optimization control for the regeneratively cooled engine.

[0026] Firstly, a regenerative cooling ramjet engine overtemperature protection strategy based on integrated control of the engine and the flight is designed. Figure 1 When the engine overheats, the aircraft and engine integrated control strategy is adopted. The aircraft reduces the speed of the aircraft by increasing the drag by ruddering and increasing the flight angle of attack, thereby reducing the heat load of the engine. The engine controls the engine temperature through the over-temperature protection temperature control algorithm. When the engine temperature is effectively controlled, it returns to the normal cruising state.

[0027] Then, the extreme value search control system of the engine temperature is designed. The control system mainly consists of an extreme value search controller and an engine temperature system, such as Figure 2 As shown. Figure 2 middle, T Indicates the actual operating temperature of the engine. is the fuel mass flow rate To the actual engine temperature T The mapping function of For function The minimum value of is the value of the independent variable when the function reaches its minimum value, is the engine temperature data value after high-pass filtering. The extreme value search controller controls the amount (i.e., fuel flow rate - Figure 3 The engine temperature system receives the new control quantity and then takes action to form a new temperature output. After multiple rounds of control iterations, the temperature extreme value is self-optimized and the minimum temperature is reached within a certain temperature range. Figure 3 shown.

[0028] Next, the extremum search controller is designed in detail.

[0029] For the disturbance signal amplitude in the extreme value search controllera , should be large enough to produce a certain change in the system output. a When , the system adjustment speed is improved and the signal-to-noise ratio is improved; if a If it is too large, the system will fluctuate greatly around when it approaches a stable state.

[0030] The angular frequency parameter of the sinusoidal excitation signal in the controller is ω , the design value should be greater than the natural frequency of the system. ω , the system adjustment speed is improved.

[0031] For the high pass filter in the controller s / ( s + h ), the design parameters can remove the oscillation signal before demodulation ρ The DC and slowly varying components of h is the filter frequency.

[0032] For the parameters in the controller k The selection of mainly follows the following rules: k When it increases, the adjustment speed of the system increases; if k If it is too large, it will cause system instability.

[0033] According to the above steps, over-temperature protection of the regenerative cooling engine can be achieved, effectively ensuring that the engine operates within a normal range.

[0034] When the engine overheats, over-temperature protection measures are implemented from the perspective of integrated control of the aircraft and the engine. Figure 1 This is a temperature protection process for regeneratively cooled ramjet engines based on integrated flight-engine control. For aircraft, flight status adjustment is required, and the main strategy is to slow down the aircraft to a safe speed range, thereby reducing the heat load of the engine flow, so that the engine can work in a safe area again. The main measures to slow down the aircraft include increasing the drag by ruddering and increasing the flight angle of attack. Measures to slow down the aircraft by reducing the fuel flow should be avoided, because this deceleration measure may conflict with the goal of the engine's own temperature control.

[0035] The temperature protection strategy of the engine itself is to reduce the engine temperature in the shortest time and restore it to the normal operating temperature range. The engine temperature control system based on the extreme value search algorithm is designed, such as Figure 2The engine temperature protection control system is mainly composed of an extreme value search controller and an engine temperature system. The extreme value search controller calculates the control quantity (fuel flow) according to the real-time temperature feedback from the engine temperature system. The engine temperature system receives the new control quantity and then acts to form a new temperature output. After multiple rounds of control iterations, the self-optimization of the temperature extreme value is completed, and the minimum temperature is reached within a certain temperature range, as shown in Figure 1. Figure 3 shown.

[0036] The extreme value search control used in the present invention is a method in adaptive control. This method does not require obtaining a specific mathematical model of the engine temperature system, and can be used to deal with the control problem of the engine temperature nonlinear control system. The extreme value search control estimates the gradient of the engine temperature objective function by adding a sinusoidal disturbance to the fuel flow control amount, and then adjusts the control amount to achieve the optimal output of the system.

[0037] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A regenerative cooling ramjet engine over-temperature protection method based on integrated control of the engine and the aircraft, characterized in that: Adopt an engine temperature protection strategy based on the idea of ​​integrated control of the aircraft and the engine and a temperature self-optimization control method for the engine itself; The engine temperature protection strategy based on the integrated control concept of aircraft and engine means that: the engine temperature control method adopts the method of joint control of aircraft and engine. When the engine temperature exceeds the safety limit, in addition to the engine itself executing control actions, the aircraft must also cooperate with the engine to take corresponding control measures; The temperature self-optimization control for the engine itself means: designing an engine temperature control algorithm for the engine itself, which uses a self-optimization method to quickly adjust the engine temperature to the minimum value within the constraint range.

2. The over-temperature protection method for a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft according to claim 1 is characterized in that: When the engine temperature exceeds the safety boundary, a joint control strategy of the aircraft and the engine is adopted. That is, the aircraft reduces the speed of the aircraft to the safe domain by increasing the drag by ruddering and increasing the flight angle of attack, thereby reducing the thermal load of the engine. The engine itself adjusts the temperature of the engine body through a temperature control algorithm. When the engine temperature is effectively controlled, it returns to normal cruising working state.

3. The over-temperature protection method for a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft according to claim 1 is characterized in that: The engine temperature protection strategy based on the integrated control concept of the aircraft and the engine includes the following steps: (1) Monitor the engine temperature status in real time to determine whether the engine temperature is within the safety limit; (2) If the engine temperature exceeds the temperature safety boundary, the aircraft and engine integrated control strategy is adopted. The aircraft reduces the speed of the aircraft by increasing the drag and the flight angle of attack, thereby reducing the heat load of the engine. The engine itself adjusts the engine temperature through the temperature control algorithm. (3) When the engine temperature returns to within the safe range, the aircraft and engine return to normal cruise operating conditions.

4. The over-temperature protection method for a regeneratively cooled ramjet engine based on integrated control of the engine and the flight according to claim 1 is characterized in that: The temperature self-optimization control method for the engine itself includes the design of extreme value search controller and engine temperature system: The extreme value search controller calculates the fuel flow control amount according to the real-time temperature feedback from the engine temperature system. After receiving the new control amount, the engine temperature system takes effect and forms a new temperature output. After multiple rounds of control iterations, the self-optimization of the temperature extreme value is completed and the minimum temperature is reached within a certain temperature range.

5. The over-temperature protection method for a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft according to claim 1, characterized in that: The engine temperature self-optimization control means that the engine temperature system outputs the real-time temperature of the engine, removes the DC component of the oscillation signal after passing through a high-pass filter, and then adds a sinusoidal signal to demodulate the signal to obtain a demodulated signal ,use The controller calculates the best estimate of the fuel mass flow rate ,in k is an integral gain, s is the Laplace variable, and finally through The new fuel control amount is obtained by sinusoidal modulation signal .

6. The over-temperature protection method for a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft according to claim 4 is characterized in that: The temperature self-optimization control for the engine itself includes the following steps: (1) Design the disturbance signal amplitude in the extreme value search controller a , design the angular frequency parameters of the sinusoidal excitation signal in the extreme value search controller ω , the input signal u Add a sinusoidal disturbance to (2) Input signal u Enter the engine temperature system, and the system outputs the real-time temperature signal of the engine; (3) Design of high-pass filter in controller s / ( s + h ), high-pass filter the output temperature signal, where s is the complex variable in Laplace transform, h is the filtering frequency; (4) Design the integral gain in the controller k , demodulate the signal and integrate it to get the best estimate of the fuel mass flow rate, and finally add it to the input signal u middle.

7. The over-temperature protection method for a regeneratively cooled ramjet engine based on integrated control of the engine and the aircraft according to claim 6 is characterized in that: The design method for the extreme value search controller is: For the disturbance signal amplitude in the extreme value search controller a , its value should make the system output change. a When it increases, the speed of system adjustment is improved, which enables the system to converge to the target value neighborhood faster; Select a The principle of value is: when the system reaches stability, u 30%~50% of the average value; The angular frequency parameter of the sinusoidal excitation signal in the controller is ω , the design value should be greater than the natural frequency of the system; when increasing ω When the system is adjusted, the adjustment speed is improved; For the high pass filter in the controller s / ( s + h ), where h is the filter frequency to remove the oscillation signal before demodulation ρ The DC component of For the integral gain in the controller k The selection of mainly follows the following rules: k When it increases, the adjustment speed of the system increases; if k If the integral gain is too large, the system will be unstable. k The selection of must ensure both the adjustment speed and the system stability, and the most suitable integral gain value should be debugged according to the actual system characteristics.

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