Scramjet isolation section boundary layer suction control system and method

Abstract

The present invention belongs to the field of scramjet isolation section suction control, and relates to a scramjet isolation section boundary layer suction control system and method. The control system includes a scramjet, a fuzzy control system, and a boundary layer suction system; the fuzzy control system includes a wall pressure sensor and an FPGA development board with a shock wave train leading edge position detection algorithm and a fuzzy controller, and the boundary layer suction system includes a suction box, a suction device, and a drive circuit. The controller of the present invention has a simple structure and a reliable algorithm, and realizes the adaptive control of the suction of the boundary layer of the scramjet isolation section by using the fuzzy controller, the wall pressure sensor, and the shock wave train leading edge position detection algorithm; a practically applicable scramjet boundary layer active suction control system is proposed; the proposed control system solves the problems of high flow loss and fixed suction parameters faced by passive suction.

Description

Technical Field

[0001] The invention belongs to the field of scramjet engine isolation section suction control, and relates to a scramjet engine isolation section boundary layer suction control system and method. Background Art

[0002] The scramjet engine has the advantages of light weight, high unit thrust, larger payload and faster speed. It is the core propulsion system of hypersonic aircraft and is considered to be one of the best propulsion systems for aircraft to achieve hypersonic flight in the atmosphere. The isolation section is one of the important components of the scramjet engine. Its function is to prevent the high pressure and disturbance generated by the combustion chamber from being transmitted to the inlet duct, preventing the inlet duct from failing to start.

[0003] In order to prevent the occurrence of non-starting phenomenon and further widen the working range of the engine, it is necessary to control the flow of the boundary layer in the isolation section. Boundary layer suction is an effective flow control method. It discharges low-speed fluid out of the flow channel by opening grooves or holes on the wall of the isolation section, so that the mainstream high-momentum fluid re-occupies the wall surface, increases the momentum of the wall-adhering fluid, thereby suppressing the shock wave train from being transmitted to the inlet duct, and controlling the leading edge position of the shock wave train within a reasonable range, so that the scramjet engine can work continuously and stably. Traditional boundary layer suction uses natural pressure difference to perform suction by opening holes or grooves on the wall. It has reliable performance and is easy to implement. It has been practically applied on some scramjet engine models. However, its parameters are fixed, and its output characteristics cannot be changed according to the external environment. Under a wide range of multi-operating conditions, it is difficult to achieve real-time optimal suction control of the isolation section of the scramjet engine. In view of the problems faced by current boundary layer suction, the present invention proposes a boundary layer suction control system and method for the isolation section of a scramjet engine based on fuzzy control. The proposed control system and control method can identify the leading edge position of the shock wave train in the isolation section in real time, and adjust the suction parameters according to the change of the leading edge position of the shock wave train, and have a certain degree of adaptability. Summary of the invention

[0004] In view of the shortcomings and difficulties existing in the prior art, the present invention provides a control system and method for the boundary layer suction of the isolation section of a scramjet engine, which controls the shock wave train in the isolation section to prevent it from being transmitted forward to the inlet duct, thereby preventing the inlet duct from failing to start, and changes the suction parameters according to the different leading edge positions of the shock wave train in the isolation section to achieve adaptive control of the boundary layer suction.

[0005] A scramjet isolation section boundary layer suction control system, comprising: a scramjet engine, a fuzzy control system, and a boundary layer suction system;

[0006] Scramjet engine: the controlled object of the control system;

[0007] The fuzzy control system comprises a wall pressure sensor and an FPGA development board provided with a shock wave train leading edge position detection algorithm and a fuzzy controller. The wall pressure sensors are respectively arranged on the upper and lower walls near the entrance of the isolation section to detect the magnitude of the reference pressure. The wall pressure sensors are evenly arranged on the upper and lower walls from the suction block in the isolation section to the outlet of the isolation section to detect the magnitude of the pressure at the current position. The pressure sensor is connected to the FPGA development board to feed back the pressure signal to the development board in real time. The FPGA development board is provided with a shock wave train leading edge position detection algorithm and a fuzzy controller. The shock wave train leading edge position detection algorithm realizes the calculation of the shock wave train leading edge position in the isolation section by inputting the discrete wall pressure signal, and the fuzzy controller realizes the adaptive control of the shock wave train leading edge position to the electrical signal of the suction box valve.

[0008] The boundary layer suction system comprises a suction box, a suction device and a driving circuit, wherein the boundary layer suction is completed by the pressure difference between the isolation section and the suction box; a pressure valve is provided on the suction box to control the pressure in the suction box, and the suction device comprises a suction block with a small hole, a pipeline and a check valve; the pressure valve changes the pressure in the suction box according to the size of the electrical signal, thereby changing the pressure difference between the isolation section and the suction box, thereby changing the suction back pressure; the check valve is arranged in the pipeline to prevent the airflow backflow caused by the pressure in the suction box being greater than the pressure in the isolation section; a suction hole is provided in the suction block, the inlet of the suction hole is tightly coupled with the wall of the isolation section of the scramjet engine, the outlet of the suction hole is connected to the suction box through a pipeline, and the suction of the isolation section is controlled according to the different pressures in the suction box; the driving circuit realizes the matching of the output signal of the FPGA chip to the control signal of the pressure valve.

[0009] As a preferred method, the shock wave train in the isolation section is controlled not to be transmitted forward to the air inlet to prevent the air inlet from failing to start, and the suction parameters are changed according to the different leading edge positions of the shock wave train in the isolation section to achieve adaptive control of boundary layer suction.

[0010] As a preferred embodiment, the wall pressure sensor is an XTEL-190-50A wall pressure sensor produced by Kulite.

[0011] As a preferred embodiment, the FPGA development board model is Zynq UltraScale+ ZU7.

[0012] The present invention also provides a scramjet isolation section boundary layer suction control method, which is based on the above control system and includes the following steps:

[0013] S1: The front edge position of the shock train in the isolation section is detected through the pressure sensor, scramjet engine, FPGA development board and shock train front edge detection algorithm;

[0014] S2: Build a fuzzy control system and set fuzzy rules to realize the input of the front edge position of the isolation section shock wave train to the output of the electrical signal control quantity, which is realized by the fuzzy controller of FPGA;

[0015] S3: using a suction device through a boundary suction system to achieve a change from an electrical signal change to a suction back pressure change;

[0016] S4: Adaptive boundary layer suction with different suction back pressures according to the different positions of the shock wave leading edge in the scramjet isolation section.

[0017] The beneficial effects of the present invention are:

[0018] (1) The controller has a simple structure and a reliable algorithm. The adaptive control of the boundary layer suction of the isolation section of the scramjet engine is realized by using a fuzzy controller, a wall pressure sensor, and a shock train leading edge position detection algorithm.

[0019] (2) A practically applicable active suction control system for the boundary layer of a scramjet engine is proposed;

[0020] (3) The proposed control system solves the problems of high flow loss and fixed suction parameters faced by passive suction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is the overall block diagram of the control system proposed by the present invention;

[0023] Figure 3 It is a schematic diagram of a method for detecting the leading edge position of a shock wave train in an isolation section using a pressure ratio method according to the present invention;

[0024] Figure 4 This is a block diagram of the fuzzy control system of the present invention;

[0025] Figure 5 This is a structural diagram of the suction block of the present invention;

[0026] Figure 6 This is a diagram of the adaptive control structure from the leading edge position of the shock wave train to the suction back pressure in Example 1 of the present invention.

[0027] 11-upper wall inlet pressure sensor, 12-upper wall suction block, 13-upper wall pipeline, 14-upper wall check valve, 15-upper wall suction box pressure valve, 16-upper wall suction box, 2-pressure sensor;

[0028] 21-lower wall inlet pressure sensor, 22-lower wall suction block, 23-lower wall pipeline, 24-lower wall check valve, 25-lower wall suction box pressure valve, 26-lower wall suction box;

[0029] 3-suction hole outlet, 4-suction block, 5-suction hole inlet. DETAILED DESCRIPTION

[0030] 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.

[0031] Example 1

[0032] like Figure 2 As shown, a scramjet isolation section boundary layer suction control system comprises: a scramjet engine, a fuzzy control system, and a boundary layer suction system;

[0033] The scramjet engine is the controlled object of the present invention. Determine the geometric configuration of the isolation section and the suction structure of the isolation section. First, determine the height and width of the isolation section entrance, the overall length of the isolation section, and the cross-sectional configuration of the isolation section. Then determine the number of openings in the suction blocks on the upper and lower walls of the isolation section and the horizontal distance between the suction blocks and the isolation section outlet. Then determine the size, shape, and length of the suction openings and the suction

[0034] The angle between the suction hole and the gas flow direction in the isolation section.

[0035] like Figure 6 As shown, the fuzzy control system includes a wall pressure sensor and an FPGA development board with a shock wave train leading edge position detection algorithm and a fuzzy controller. A wall pressure sensor is arranged on the upper and lower walls near the entrance of the isolation section to detect the size of the reference pressure, and wall pressure sensors 2 are evenly arranged on the upper and lower walls from the suction block to the outlet of the isolation section in the isolation section to detect the pressure size at the current position. The pressure sensor is connected to the FPGA development board to feed back the pressure signal to the development board in real time. The shock wave train leading edge position detection algorithm and the fuzzy controller are deployed in the FPGA development board. The shock wave train leading edge position detection algorithm realizes the calculation of the shock wave train leading edge position in the isolation section by inputting the discrete wall pressure signal, and the fuzzy controller realizes the adaptive control of the shock wave train leading edge position to the electrical signal of the suction box valve.

[0036] There is a pressure valve on the suction box to control the pressure in the suction box. The suction device includes a suction block with small holes, a pipeline and a check valve; the pressure valve changes the pressure in the suction box according to the size of the electrical signal, thereby changing the pressure difference between the isolation section and the suction box, thereby changing the suction back pressure; the check valve is placed in the pipeline to prevent the air flow backflow caused by the pressure in the suction box being greater than the pressure in the isolation section; a suction hole is opened in the suction block, the inlet of the suction hole is tightly coupled with the wall of the isolation section of the scramjet engine, and the outlet of the suction hole is connected to the suction box through a pipeline, and the suction of the isolation section is controlled according to the different pressures in the suction box; the driving circuit realizes the matching of the output signal of the FPGA chip to the control signal of the pressure valve.

[0037] The shock wave train in the isolation section is controlled not to be transmitted forward to the inlet duct to prevent the inlet duct from failing to start, and the suction parameters are changed according to the different leading edge positions of the shock wave train in the isolation section to achieve adaptive control of boundary layer suction.

[0038] like Figure 1 As shown, the boundary layer suction system includes a suction box, a suction device and a driving circuit, and the boundary layer suction is completed by the pressure difference between the isolation section and the suction box. A wall pressure sensor is arranged on the upper and lower walls near the inlet of the isolation section, respectively, which are an upper wall inlet pressure sensor 11 and a lower wall inlet pressure sensor 21. The upper wall suction device includes an upper wall suction block 12 with a small hole, an upper wall pipe 13, an upper wall check valve 14, an upper wall suction box 16 and an upper wall suction box pressure valve 15. A circular suction hole is opened in the upper wall suction block 12, and the suction hole inlet is tightly coupled with the upper wall of the scramjet isolation section. The suction hole outlet is connected to the upper wall suction box 16 through the upper wall pipe 13. The upper wall check valve 14 and the upper wall suction box pressure valve 15 are installed on the connecting pipe. The isolation section is suctioned and controlled according to the different pressures in the suction box.

[0039] The lower wall suction device includes a lower wall suction block 22 with a small hole, a lower wall pipe 23, a lower wall check valve 24, a lower wall suction box 26 and a lower wall suction box pressure valve 25. A circular suction hole is opened in the lower wall suction block 22, the suction hole inlet is tightly coupled with the lower wall of the scramjet isolation section, the suction hole outlet is connected to the lower wall suction box 26 through the lower wall pipe 23, and the lower wall check valve 24 and the lower wall suction box pressure valve 25 are installed on the connecting pipe to control the suction of the isolation section according to the different pressures in the suction box.

[0040] There is a pressure valve on the suction box to control the pressure in the suction box. The pressure valve changes the pressure in the suction box according to the size of the electrical signal, thereby changing the pressure difference between the isolation section and the suction box, thereby changing the suction back pressure.

[0041] The upper wall check valve 14 and the lower wall check valve 24 are arranged in the pipeline to prevent the air flow from flowing back when the pressure in the suction box is greater than the pressure in the isolation section.

[0042] Preferably, the wall pressure sensor is an XTEL-190-50A wall pressure sensor produced by Kulite;

[0043] Preferably, the FPGA development board model is Zynq UltraScale+ ZU7.

[0044] Example 2

[0045] A method for controlling the suction of a boundary layer of an isolation section of a scramjet engine is implemented based on the control system described in Example 1, and includes the following steps:

[0046] S1: The front edge position of the shock train in the isolation section is detected through the pressure sensor, scramjet engine, FPGA development board and shock train front edge detection algorithm;

[0047] S2: Build a fuzzy control system and set fuzzy rules to realize the input of the front edge position of the isolation section shock wave train to the output of the electrical signal control quantity, which is realized by the fuzzy controller of FPGA;

[0048] S3: using a suction device through a boundary suction system to achieve a change from an electrical signal change to a suction back pressure change;

[0049] S4: Adaptive boundary layer suction with different suction back pressures according to the different positions of the shock wave leading edge in the scramjet isolation section.

[0050] Example 3

[0051] The difference between this embodiment and embodiment 2 is that:

[0052] Step S1 is specifically as follows:

[0053] If you want to directly observe the flow process in the isolation section and obtain the leading edge position of the shock train, it is usually necessary to use optical technologies such as PIV and high-speed cameras to achieve this. At this time, the schlieren image obtained in the isolation section cannot be directly used as the feedback input of the control system. It will usually involve a series of image processing technologies to perform image processing and feature extraction to finally obtain the leading edge position of the shock train as the input of the control system. Through the wall pressure sensor combined with the shock train leading edge position detection algorithm, the approximate shock train leading edge position can be indirectly obtained through discrete wall pressure points. In the present invention, the shock train leading edge position is indirectly obtained through the pressure ratio method and discrete pressure data in the detection algorithm. Figure 1As shown, 14 pressure sensors are arranged between the suction hole and the outlet of the isolation section, with 2 pressure sensors in each row, for a total of 7 rows. The 2 pressure sensors in each row are respectively located near the upper and lower walls. In addition, one pressure sensor is arranged on the upper and lower walls near the entrance of the isolation section. By utilizing the sudden and discontinuous pressure changes before and after the shock wave, the position of the shock wave train can be detected by the pressure sensor. In the present invention, the pressure ratio method is used to identify the leading edge position of the shock wave train in the isolation section. Its essence is to identify the leading edge position of the shock wave train based on the characteristic that the shock wave train will cause a significant pressure surge in the wall pressure. The pressure ratio method first requires the selection of a reference pressure. Utilizing the characteristic that the upstream pressure of the shock wave train in the straight isolation section is basically unchanged, one pressure sensor is arranged on the upper and lower walls near the entrance of the isolation section, and the pressure measured by the pressure sensor is used as the reference pressure of the upper and lower walls. P T1, P T2 ( P T1 represents the upper wall reference pressure, P T2 Represents the reference pressure of the lower wall). After obtaining the reference voltage, the pressure at each measuring point is measured, that is, the pressure measured by the 14 pressure sensors arranged between the suction hole in the isolation section and the outlet of the isolation section. and , ( Represents the static pressure measured by the 7 sensors on the upper wall, represents the static pressure measured by the 7 sensors on the lower wall). Assume that the total operation time of the scramjet engine is T , the sampling interval is Δt, and the constant k Representative k sampling times, and the total number of sampling times during the total running time is n The three satisfy the following equation:

[0054] (1)

[0055] and There are two groups k Δ t The variable that changes with the change is written as and Then, the upper wall pressure ratio vector is completed through equations (2) and (3): and the lower wall pressure ratio vector Creation:

[0056] (2)

[0057] (3)

[0058] By linear interpolation, a line is constructed passing through the above-mentioned pressure ratio point. Then, by linear interpolation, a pressure sensor position distribution line in the isolation section is constructed. In the present invention, since the pressure sensors are distributed at equal intervals, the constructed pressure sensor position distribution line is a straight line. After completing the construction of the pressure ratio line and the pressure sensor position distribution line, the following formulas (4) and (5) are used to determine the leading edge position of the upper and lower wall shock wave train in the isolation section:

[0059]

[0060] According to the experimental conclusions, When the pressure ratio method is used to solve the shock train front edge position in the isolation section, the error between the shock train front edge position obtained from the actual schlieren diagram is the smallest, that is, , They are respectively the vectors of the installation positions of the wall pressure sensors on the upper wall and the lower wall, which are respectively constructed into the upper wall pressure sensor position distribution line and the lower wall pressure sensor position distribution line by linear interpolation method. It is the mapping value of the target point on the upper wall and lower wall pressure ratio line where the pressure rise ratio is 1.5 on its corresponding position distribution line at each sampling moment. Figure 3 This is a schematic diagram of solving the leading edge position of a continuous shock train using the pressure ratio method and discrete wall pressure sensors. In the figure, the hexagon is the pressure ratio point, the line connecting the hexagons is the pressure ratio line, the five-pointed star is the target point with a pressure rise ratio of 1.5, and the horizontal axis is the pressure sensor position distribution line. The horizontal axis value corresponding to the target point at the pressure rise ratio of 1.5 is used as the leading edge position of the shock train in the isolation section at the current moment, thereby realizing the real-time measurement of the leading edge position of the shock train in the isolation section.

[0061] Example 4

[0062] The difference between this embodiment and embodiment 2 is that:

[0063] Step S2 is specifically as follows:

[0064] Build a fuzzy controller to realize the input of the leading edge position of the shock wave train to the output of the electrical signal control quantity. Figure 4 is a block diagram of a fuzzy control system. The fuzzy controller is a one-dimensional fuzzy controller, whose input is the current shock train leading edge position in the isolation section, the input domain is [0, M], and the fuzzy subset of the input is defined as follows: {PB, PM, PS, ZO, NS, NM, NB}, where PB represents the row of pressure sensors closest to the suction hole horizontally detecting the arrival of the shock train leading edge, PM represents the row of pressure sensors closest to the suction hole horizontally detecting the arrival of the shock train leading edge, and so on, NB represents the row of pressure sensors farthest from the suction hole horizontally detecting the arrival of the shock train leading edge. The input membership function selects a triangular membership function.

[0065] The output of the one-dimensional fuzzy controller is the electrical signal of the pressure valve in the suction box. The domain of the output is [0, N]. The fuzzy subset of the output is defined as follows: {PB, PBM, PBS, PS, PSM, PSS, ZO}, where PB represents the maximum value of the electrical signal, PBM represents the second maximum value of the electrical signal, and so on. ZO represents the electrical signal value of zero. The output membership function also selects the triangular membership function.

[0066] Therefore, the fuzzy rules of the constructed one-dimensional fuzzy controller include:

[0067] Rule 1: If the input is PB, the output is PB;

[0068] Rule 2: If the input is PM, the output is PBM;

[0069] Rule 3: If the input is PS, the output is PBS;

[0070] Rule 4: If the input is ZO, the output is PS;

[0071] Rule 5: If the input is NS, the output is PSM;

[0072] Rule 6: If the input is NM, the output is PSS;

[0073] Rule 7: If the input is NB, the output is ZO.

[0074] Under Rule 1, the leading edge of the shock train is closest to the entrance of the isolation section, and a larger suction back pressure is required to limit its continued forward movement, so the output of the electrical signal control quantity reaches the maximum value. Under Rule 7, the leading edge of the shock train is farthest from the entrance of the isolation section, and suction is not required to optimize the flow structure in the isolation section, so the output of the electrical signal control quantity reaches the minimum value. In other cases, different electrical signal control quantity outputs are obtained according to different positions of the leading edge of the shock train in the isolation section, corresponding to different rules. Based on the above fuzzy rules and the real-time shock train leading edge position obtained by the feedback signal of the wall pressure sensor in the isolation section, the electrical signal control quantity output of the pressure valve in the suction box can be obtained.

[0075] Example 5

[0076] The difference between this embodiment and embodiment 2 is that step S3 is specifically:

[0077] The electrical signal output of the fuzzy controller module cannot directly change the suction parameters in the isolation section. In the present invention, the horizontally distributed suction holes in the upper and lower wall suction blocks are connected to the suction box through pipelines, and natural suction is achieved through the pressure difference between the isolation section and the suction box. Figure 5 This is the structure diagram of the suction block.

[0078] like Figure 5 As shown, the suction block 4 is provided with a suction hole outlet 3 and a suction hole inlet 5 .

[0079] The suction parameters in the isolation section can be changed by changing the suction pressure in the suction box. The internal pressure is changed by changing the value of the pressure valve on the suction box through an electrical signal, so that the pressure difference between the isolation section and the suction box changes to change the suction parameters in the isolation section. In the case of rule 1, if the input is PB, the front edge of the shock wave train is closest to the suction hole, the boundary layer thickness is thick, and a larger suction back pressure is required to weaken the boundary layer thickness and reduce the size of the separation zone. Therefore, the output is PB, the electrical signal reaches the maximum value and acts on the pressure valve in the suction box, the pressure in the suction box reaches the minimum value, the pressure difference between the isolation section and the suction box reaches the maximum value, the low-speed flow gas discharged through the opening reaches the maximum value, and the amount of gas sucked in the boundary layer reaches the maximum value. In the case of rule 7, if the input is NB, the front edge of the shock wave train is farthest from the suction hole, the boundary layer thickness is thin, and good flow performance can be obtained without suction in the isolation section. Moreover, when the leading edge of the shock wave train is far away from the suction area in the isolation section, the boundary layer suction has little effect on the flow field in the isolation section. The boundary layer suction at this stage will cause a certain degree of flow loss. Therefore, the output is ZO, the electrical signal reaches the minimum value 0 and acts on the pressure valve in the suction box, the pressure in the suction box reaches the maximum value, the gas pressure in the suction box is close to or greater than the gas pressure in the isolation section, and the check valve is used to prevent the gas in the suction box from flowing back into the isolation section. In this case, there is approximately no suction in the isolation section, so it can be considered that there is no suction flow loss. In other cases, different rules correspond to different leading edge positions of the shock wave train, and then correspond to different electrical signals and act on the pressure valve in the suction box. The pressure in the suction box changes accordingly according to the input electrical signal. The suction back pressure changes accordingly according to the change in the pressure in the suction box, and finally the change from electrical signal input to suction back pressure is realized.

[0080] Example 6

[0081] The difference between this embodiment and embodiment 2 is that step S4 is specifically:

[0082] S4: Adaptive boundary layer suction with different suction back pressures according to the different positions of the shock wave leading edge in the scramjet isolation section.

[0083] When the back pressure of the combustion chamber is large, the shock train in the isolation section propagates rapidly, the leading edge of the shock train is close to the entrance of the isolation section, the safety margin is small, and the inlet duct failure may occur at any time. In this case, the current leading edge position of the shock train is obtained based on the feedback data of the pressure sensor and the pre-set detection algorithm. The current leading edge position of the shock train is input into the fuzzy control system. According to the pre-set expert experience, it is judged that the failure to start is very likely to occur at this time, and the suction back pressure needs to be reduced to obtain a larger pressure difference to discharge more low-speed gas close to the wall of the isolation section. The fuzzy control system outputs a large voltage, which acts on the pressure valve on the suction box after the drive circuit, the pressure of the suction box is reduced, the suction back pressure is reduced, the pressure difference is increased, and more low-speed flow gas is discharged, which inhibits the shock train in the isolation section from continuing to propagate to the inlet duct and prevents the failure to start. When the back pressure of the combustion chamber is small, the flow condition in the isolation section is good, and the pressure generated by the combustion is not enough to push the shock train out of the isolation section, and the inlet duct failure does not occur. In this case, the current leading edge position of the shock train is obtained based on the feedback data of the pressure sensor and the pre-set detection algorithm. The current shock wave front edge position is input into the fuzzy control system. According to the pre-set expert experience, it is judged that the flow state is good at this time, and the flow loss caused by suction should be avoided. The fuzzy control system outputs a small voltage, which acts on the pressure valve on the suction box after passing through the drive circuit. The pressure of the suction box increases, and the pressure inside the suction box is higher than the pressure inside the isolation section. The check valve is used to prevent gas backflow. The suction hole is nearly closed to prevent high flow loss caused by passive suction.

[0084] Example 7

[0085] A scramjet isolation section boundary layer suction control system, the scramjet engine has a rectangular inlet section, and is composed of an equal straight section and an expansion section. A suction block is set at a certain distance from the inlet of the isolation section, and a certain number of suction holes are opened in each suction block, and the suction holes have a certain aperture and depth. The suction block is designed to be inclined at 45° to the mainstream direction in the isolation section, and the suction holes are parallel to the suction block direction. The outlet of the suction hole is connected to the suction box through a pipeline, and a check valve is provided in the pipeline. According to the experimental data of the scramjet isolation section, the pressure in the suction box is set within a certain range. Under the condition of the minimum voltage of the pressure valve, the pressure in the suction box reaches the maximum value, and under the condition of the maximum voltage of the pressure valve, the pressure in the suction box reaches the minimum value. From a certain distance from the inlet in the engine isolation section, pressure sensors are arranged, a total of 7 groups of pressure sensors, each group of 2 pressure sensors, respectively placed near the upper and lower walls, and the pressure sensors are evenly and evenly spaced. A wall pressure sensor is arranged on the upper and lower walls of the isolation section near the inlet to measure the reference pressure required by the pressure ratio method.

[0086] In order to obtain faster processing and response speed, the isolation section shock wave train leading edge position detection system and fuzzy control system are deployed in the FPGA development board. In order to obtain faster signal transmission speed, the output ends of the upper and lower wall pressure sensors are connected to the FPGA development board, and SPI serial communication is adopted between the upper and lower wall pressure sensors and the fuzzy control module. The FPGA development board collects the installation positions of the 14 upper and lower wall pressure sensors and the pressure feedback of the 14 wall pressure sensors at each sampling moment, as well as the reference pressure measured by the wall pressure sensors arranged on the upper and lower walls near the entrance of the isolation section. After obtaining these three sets of quantities, the pressure ratio method mentioned in S1 of the present invention is used for calculation to obtain the real-time shock wave train leading edge position in the isolation section.

[0087] Two wall pressure sensors near the entrance of the isolation section and 14 pressure sensors evenly distributed in the detection area of ​​the isolation section are connected to the FPGA development board, and the wall pressure at the current position is fed back in real time according to the sampling frequency. The FPGA development board receives the wall pressure feedback from the pressure sensor and the position of the pressure sensor in the isolation section, and calculates the real-time shock wave leading edge position in the isolation section according to the shock wave leading edge position detection algorithm arranged inside it.

[0088] Preferably, the wall pressure sensor is an XTEL-190-50A wall pressure sensor produced by Kulite;

[0089] Preferably, the FPGA development board model is Zynq UltraScale+ ZU7.

[0090] The shock wave front edge position is transmitted to the fuzzy control system. The shock wave front edge position input signal is normalized to [0,1] after preprocessing and transmitted to the fuzzification module in the system, which converts it into a fuzzy set. The fuzzy set is transmitted to the fuzzy reasoning module. The fuzzy reasoning module obtains the corresponding fuzzy output according to the fuzzy set input based on the corresponding rule base. The fuzzy output is converted into an accurate suction box valve electrical signal analog output after passing through the defuzzification module. The suction box valve electrical signal analog output is completed by the pin of the FPGA development board. The pin is connected to the input end of the drive circuit in the boundary layer suction system, and the output signal is amplified by the drive circuit.

[0091] Among them, the one-dimensional fuzzy rules in the fuzzy reasoning module satisfy the following rules:

[0092] Rule 1: If the input is PB, the output is PB;

[0093] Rule 2: If the input is PM, the output is PBM;

[0094] Rule 3: If the input is PS, the output is PBS;

[0095] Rule 4: If the input is ZO, the output is PS;

[0096] Rule 5: If the input is NS, the output is PSM;

[0097] Rule 6: If the input is NM, the output is PSS;

[0098] Rule 7: If the input is NB, the output is ZO.

[0099] Under Rule 1, the leading edge of the shock train is closest to the entrance of the isolation section, and a larger suction back pressure is required to limit its continued forward movement, so the output of the electrical signal control quantity reaches the maximum value. Under Rule 7, the leading edge of the shock train is farthest from the entrance of the isolation section, and suction is not required to optimize the flow structure in the isolation section, so the output of the electrical signal control quantity reaches the minimum value. In other cases, different electrical signal control quantity outputs are obtained according to different positions of the leading edge of the shock train in the isolation section, corresponding to different rules. Based on this fuzzy system and the real-time leading edge position of the shock train obtained through the feedback signal of the wall pressure sensor in the isolation section, the electrical signal control quantity output of the pressure valve in the suction box can be finally obtained.

[0100] According to different input quantities, the fuzzy controller outputs different control voltages. In order to achieve the matching of the control voltage and the input voltage of the suction box pressure valve, a drive circuit is designed to achieve voltage matching between the two. After the drive circuit, the output control voltage of the fuzzy controller is amplified and then output to the suction box pressure valve as the final output voltage. The pressure valve is used to change the pressure in the suction box within the set range. Figure 6 This is the adaptive control structure diagram from the leading edge position of the shock train to the suction back pressure. According to the pressure change, the multi-condition adaptive suction control is realized, which includes no suction when the leading edge position of the shock train in the isolation section is farthest from the isolation section entrance, suction with a small suction back pressure when the leading edge position of the shock train in the isolation section is far from the isolation section entrance, and suction with a large suction back pressure when the leading edge position of the shock train in the isolation section is close to the isolation section entrance.

[0101] After completing the algorithm deployment and actual hardware connection, flight experiments were carried out to verify the effectiveness of the proposed scramjet engine isolation section suction control method and the overall control system.

[0102] 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 scramjet isolation section boundary layer suction control system, characterized in that: include: Includes: scramjet engine, fuzzy control system, boundary layer suction system; Scramjet engine: the controlled object of the control system; The fuzzy control system comprises a wall pressure sensor and an FPGA development board provided with a shock wave train leading edge position detection algorithm and a fuzzy controller. The wall pressure sensors are respectively arranged on the upper and lower walls near the entrance of the isolation section to detect the magnitude of the reference pressure. The wall pressure sensors are evenly arranged on the upper and lower walls from the suction block in the isolation section to the outlet of the isolation section to detect the magnitude of the pressure at the current position. The pressure sensor is connected to the FPGA development board to feed back the pressure signal to the development board in real time. The FPGA development board is provided with a shock wave train leading edge position detection algorithm and a fuzzy controller. The shock wave train leading edge position detection algorithm realizes the calculation of the shock wave train leading edge position in the isolation section by inputting the discrete wall pressure signal, and the fuzzy controller realizes the adaptive control of the shock wave train leading edge position to the electrical signal of the suction box valve. The boundary layer suction system comprises a suction box, a suction device and a driving circuit, wherein the boundary layer suction is completed by the pressure difference between the isolation section and the suction box; a pressure valve is provided on the suction box to control the pressure in the suction box, and the suction device comprises a suction block with a small hole, a pipeline and a check valve; the pressure valve changes the pressure in the suction box according to the size of the electrical signal, thereby changing the pressure difference between the isolation section and the suction box, thereby changing the suction back pressure; the check valve is arranged in the pipeline to prevent the airflow backflow caused by the pressure in the suction box being greater than the pressure in the isolation section; a suction hole is provided in the suction block, the inlet of the suction hole is tightly coupled with the wall of the isolation section of the scramjet engine, and the outlet of the suction hole is connected to the suction box through a pipeline, and the suction of the isolation section is controlled according to the different pressures in the suction box; the driving circuit realizes the matching of the output signal of the FPGA chip to the control signal of the pressure valve; The shock wave train in the isolation section is controlled not to be transmitted forward to the inlet duct to prevent the inlet duct from failing to start, and the suction parameters are changed according to the different leading edge positions of the shock wave train in the isolation section to achieve adaptive control of boundary layer suction.

2. A method for controlling the suction of the boundary layer of the isolation section of a scramjet engine, based on the control system of claim 1, characterized in that The following steps are involved: S1: The front edge position of the shock train in the isolation section is detected through the pressure sensor, scramjet engine, FPGA development board and shock train front edge detection algorithm; S2: Build a fuzzy control system and set fuzzy rules to realize the input of the front edge position of the isolation section shock wave train to the output of the electrical signal control quantity, which is realized by the fuzzy controller of FPGA; S3: using a suction device through a boundary suction system to achieve a change from an electrical signal change to a suction back pressure change; S4: Adaptive boundary layer suction with different suction back pressures according to the different positions of the shock wave leading edge in the scramjet isolation section.

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