Dynamic shock wave closed-loop control method

Abstract

The method and verification device for dynamic shock wave closed-loop control disclosed in the present invention at least partially solve the technical problems of unstable operation such as shock wave pulsation in the inlet of the existing engine. Based on the real-time control of the dynamic shock wave induced by the dynamic shock wave generator by the arc plasma exciter, the verification device sequentially arranges the plasma exciter and the dynamic shock wave generator along the airflow direction, and a first pressure sensor is installed at the upstream position of the plasma exciter, and a second pressure sensor is installed at a preset position downstream of the rotating shaft of the shock wave generator along the airflow direction; the current shock wave intensity is determined by obtaining the measurement values ​​of the first sensor and the second sensor, and the closed-loop controller monitors the switch state quantity of the plasma exciter and the theoretical value of the shock wave intensity in real time; according to the currently measured shock wave intensity, a closed-loop control is formed and the working parameters of the plasma exciter are adjusted in real time to achieve the stable control of the dynamic shock wave pressure ratio and achieve the preset control target value.

Description

Technical Field

[0001] The invention belongs to plasma closed-loop active flow control technology, and in particular relates to a dynamic shock wave closed-loop control method. Background Art

[0002] In (hyper)sonic flight, shock wave / boundary layer interaction is common in the flow field outside the aircraft and inside the engine. The pulsating shock waves generated by the disturbance of the incoming flow, the change of the angle of attack or the separation of the boundary layer during flight will cause local pressure pulsation and heat load, which has an important impact on the fatigue life, structural integrity and material selection of the aircraft and its components. To further improve the design of supersonic aircraft and their power plants, it is necessary to have a clearer understanding of basic flow phenomena such as shock waves and shock wave / boundary layer interaction, boundary layer separation, and to achieve rapid and effective control of local deterioration of the flow field.

[0003] Early studies attempted to use a shock wave shape controller, publication number CN 101033763A, to achieve inlet shock wave control. Specifically, the high-pressure gas was introduced into the isolation section and then ejected from the inlet wall to achieve shock wave control under non-design conditions. Further research used this bleed air control scheme to achieve an increase in the flow coefficient of the inlet at low Mach numbers and a decrease in the forebody drag coefficient. However, this mechanical control scheme based on bleed air has a slow response problem in high-speed flow field control; at the same time, the disturbance of the jet may cause shock wave pulsation; in addition, when the flow field does not need to be controlled, the open-hole bleed air will lead to the existence of a gas dead cavity, causing additional air flow loss and thermal protection problems.

[0004] Based on the characteristics of plasma actuators such as no inertia, fast response, wide bandwidth, and flexible installation and control, plasma active flow control technology has been widely studied in the field of supersonic flow field control. The local arc wire plasma actuator (US 2006 / 0005545 A1) for mixing and noise reduction is arranged at the circumferential position of the nozzle outlet, and uses high-frequency electrode discharge to form plasma disturbances to control the jet. The test results effectively confirm its effectiveness in enhancing jet mixing. The combined plasma flow control device (CN 110131072B) comprehensively utilizes high-frequency pulse arc plasma actuators and dielectric barrier discharge plasma actuators to control shock waves and boundary layers at the same time, thereby reducing the intensity of shock waves and separation zones.

[0005] When the above-mentioned plasma actuator control scheme is applied to supersonic flow control, its high-frequency excitation disturbance is used to achieve the control purpose, but it also inevitably introduces high-frequency pulsation, causing unsteady pulsating motion of shock waves, which affects the stable operation of the engine intake duct, etc. Summary of the invention

[0006] In view of this, the present invention provides a dynamic shock wave closed-loop control method and a verification device thereof, which at least partially solve the technical problems of unstable operation such as shock wave pulsation in the existing engine intake duct.

[0007] A method for closed-loop control of dynamic shock waves is provided, wherein the dynamic shock waves induced by a dynamic shock wave generator are controlled based on an arc plasma exciter, wherein a first pressure sensor is installed at an upstream position of the plasma exciter along the airflow direction, and a second pressure sensor is installed at a preset position downstream of a rotating shaft of the shock wave generator;

[0008] The current shock wave intensity is determined by acquiring the measured values ​​of the first sensor and the second sensor, and the closed-loop controller monitors the switch state quantity of the plasma actuator and the theoretical value of the shock wave intensity in real time;

[0009] According to the currently measured shock wave intensity, a closed-loop control is formed and the working parameters of the plasma actuator are adjusted in real time to achieve a smooth control of the dynamic shock wave pressure ratio and achieve a preset control target value. The technical benefits of the present invention are:

[0010] (1) Compared with the existing high-frequency pulse discharge exciter, the arc discharge system provided by the present invention does not include a high-frequency excitation element, and introduces less electromagnetic interference in the flow field; the flow arc formed by the discharge of the exciter is more stable and has less pulsation, further reducing electromagnetic interference;

[0011] (2) Compared with the flow control of existing high-frequency pulse discharge exciters, which are mostly open-loop control under stable working conditions, the closed-loop control provided by the present invention realizes real-time monitoring of the control object, and the established feedback model realizes the smooth control of the pulsating shock wave, which is a significant feature that the existing open-loop plasma exciters do not have;

[0012] (3) Compared with the fixed-angle shock wave generator in the existing invention, it can achieve rapid simulation of shock wave conditions of different intensities and realize different dynamic change modes, with a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 Schematic diagram of a dynamic shock wave closed-loop control scheme based on a plasma actuator;

[0015] Figure 2 It is a control logic diagram of the closed-loop controller;

[0016] Figure 3 This is a verification diagram of the closed-loop control effect of the shock wave pressure ratio when the angle of the dynamic shock wave generator is fixed;

[0017] Figure 4 This is the verification diagram of the stable closed-loop control of the shock wave pressure ratio when the dynamic shock wave generator angle changes;

[0018] in:

[0019] 1. Dynamic shock wave generator; 2. Plasma actuator; 3-1. First pressure sensor; 3-2. First pressure sensor; 4. Support rod; 5. Closed-loop controller. DETAILED DESCRIPTION

[0020] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0021] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure 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 disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0022] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0023] Figure 1The dynamic shock wave closed-loop control device shown includes a dynamic shock wave generator 1, a position-adjustable plasma actuator 2, a first pressure sensor 3-1 and a second pressure sensor 3-2, a support rod 4, and a closed-loop controller 5. The existing dynamic shock wave generator 1 is a rotatable fan-shaped metal block, which is connected to a stepper motor through a support rod 4 below and rotates around a mounting axis under the drive of the stepper motor. When it rotates, a dynamic shock wave is formed in a supersonic flow field, and its change angle is 0° to 10°. The rotation speed can be controlled by adjusting the speed of the stepper motor.

[0024] The position-adjustable plasma exciter 2 is located upstream of the dynamic shock wave generator 1, and is composed of a discharge metal tungsten electrode and an insulating high-temperature resistant ceramic. The electrode is installed flush with the surface of the ceramic block to ensure that the exciter has minimal impact on the flow field when it is not working. The lower end is connected to a high-voltage DC circuit. The number of electrodes in the span direction can be determined according to the actual control requirements of the shock wave; the number of rows in the flow direction can be determined according to the power range required for shock wave regulation. Based on the effectiveness of shock wave control and arc stability research in the early stage, the flow distance between the electrode and the edge of the downstream ceramic block is 15 mm to 40 mm.

[0025] The first and second pressure sensors 3-1, 3-2 respectively collect the pressure information of the upstream of the supersonic flow and the wall pressure behind the oblique shock wave, and transmit them to the closed-loop controller 5 as input signals (p1, p2); the pressure sensor 3-1 located upstream is fixedly installed on the model wall, and the pressure behind the oblique shock wave is led out through the bleed hose and connected to the sensor 3-2 to avoid interference with the rotation of the dynamic shock generator 1.

[0026] Figure 2 The control method logic of the closed-loop controller shown is specifically as follows:

[0027] The measurement values ​​of the first sensor and the second sensor are obtained to determine the current shock wave intensity, and a "case" logic judgment is performed according to the current shock wave intensity to determine the working state and parameters of the plasma actuator. The judgment criteria include:

[0028] Determine the set value π of the shock wave intensity control target d , to determine whether the current shock wave intensity is greater than the set value π of the control target d If yes, the plasma actuator is adjusted to the on state and the working parameters of the plasma actuator are adjusted according to the current shock wave intensity; if no, the plasma actuator is adjusted to the off state;

[0029] When the shock wave generator is turned on, determine whether the current shock wave intensity is less than the set value π of the control target d If so, the working parameters of the plasma actuator are adjusted according to the current shock wave intensity until they are equal to the set target value;

[0030] The inviscid theoretical value of the current shock wave is obtained according to the current state of the dynamic shock wave generator, and it is determined whether the current shock wave intensity is less than the inviscid theoretical value, or when the plasma exciter is in the off state, if so, the plasma exciter is turned off. The introduction of the inviscid theoretical value can effectively ensure the self-consistency of the case judgment logic when overshoot occurs during the control process, thereby ensuring the stable operation of the plasma exciter.

[0031] In a specific implementation case of the present invention,

[0032] The angle of the dynamic shock wave generator 1 is kept constant at α=8.54°; the flow direction position of the electrode of the plasma exciter 2 is 35mm away from the edge of the alumina ceramic block, the diameter of the tungsten electrode is 1mm, the spanwise spacing is 2mm, and two pairs of electrodes are arranged in the spanwise direction. The wiring methods are -++-. At this time, the electrode discharge in the supersonic flow field forms a stable arc plasma along the flow direction with a length of 35mm. When the plasma exciter is in the open state, the closed-loop controller 5 adjusts the exciter power in real time.

[0033] Parc = 2 × 10 3 K P (π th -π d )+1×10 2 ∑(p2 / p1-π d )+1×10 3 Δ(p2 / p1),

[0034] Among them, π th is the inviscid theoretical value of the slope shock pressure ratio at the current time; π d is the target pressure ratio, and its value is 1.52. Figure 3 As shown in the figure, when the angle of the dynamic shock wave generator is fixed, K is selected P They are 0.05 and 1.0 respectively, realizing closed-loop control of the oblique shock wave pressure ratio to the specified target value.

[0035] In another specific implementation case of the present invention,

[0036] The angle α of the dynamic shock wave generator 1 varies from 7° to 9°, and the specific variation rule is α = -32t 2 +16t+7, t represents time;

[0037] The flow direction position of the plasma exciter 2 electrode is 35mm away from the edge of the alumina ceramic block, the diameter of the tungsten electrode is 1mm, the spanwise spacing is 2mm, and two pairs of electrodes are arranged in the spanwise direction. The wiring methods are -++-. At this time, the electrode discharge in the supersonic flow field forms a stable arc plasma along the flow direction, with a length of 35mm.

[0038] The arc power (Parc) and the pressure ratio difference (Δp = p2 / p1-π) are established in the closed-loop controller 5. d ), specifically:

[0039] Parc = 2 × 10 3 K P (π th -π d )+1×10 2 ∑(p2 / p1-π d )+1×10 3 Δ(p2 / p1)

[0040] Among them, π th is the inviscid theoretical value of the slope shock pressure ratio at the current time, which can be calculated based on the current slope angle; π d is the target pressure ratio, which is 1.52; K P is the proportionality coefficient, and its value is 1.0. The simulation shows that when the dynamic shock wave generator 1 changes its angle to induce the formation of a dynamic shock wave, the embodiment of the present invention can effectively control the oblique shock wave pressure ratio to stabilize to a specified target value, and the control effect is as follows: Figure 4 shown.

[0041] The present invention provides an implementation case of a dynamic shock wave closed-loop control device, comprising a dynamic shock wave generator, in which a plasma generator and a shock wave generator are arranged in sequence along the airflow direction, including a dynamic shock wave generator, and the position of the plasma exciter is adjustable. The device also comprises a closed-loop controller, a first pressure sensor and a pressure sensor, wherein: the first pressure sensor is installed in front of and close to the plasma generator, and the second pressure sensor is installed at a preset position of the shock wave generator along the airflow direction, and the closed-loop controller runs part or all of the above-mentioned method.

[0042] Implementation example Figure 1 As shown, the dynamic shock generator 1 is a rotatable fan-shaped metal block (aluminum, stainless steel, etc. can be selected), which is connected to the stepper motor (this motor is a mature product, please refer to the selection of Zhuoli Hanguang KSAV2030-ZF) through the support rod 4 below, and rotates around the installation axis under the drive of the stepper motor. The entire model is installed on the wall of the supersonic wind tunnel flow field test section. When the dynamic shock generator 1 rotates, a dynamic shock wave is formed in the supersonic flow field, and its change angle is 0°-10°, which is specifically selected as 7°~9° in this implementation case. Its rotation speed can be controlled by adjusting the movement speed of the stepper motor.

[0043] The position-adjustable plasma exciter 2 is installed upstream of the dynamic shock wave generator 1 and is composed of a discharge metal electrode (preferably a tungsten electrode) and an insulating high-temperature resistant ceramic (preferably an alumina ceramic) matrix. The electrode with a diameter of 1 mm is insulated with a heat shrink tube and installed in a 2 mm through hole in the ceramic block through solid insulating glue. The surface is kept flush to ensure that the exciter has minimal impact on the flow field when it is not working; the lower end is connected to the high-voltage discharge DC circuit, and the high-voltage power supply uses a DC power supply (refer to the selection of Glassman High Voltage, Inc. 10kV, 1A.), which can adjust the output current through weak current signals, which is convenient for association with the closed-loop control system; the number of electrodes in the span direction can be determined according to the actual control requirements of the shock wave. In this case, 4 electrodes are selected, and the wiring method is -++-; the number of flow direction rows can be determined according to the power range required for shock wave regulation. Based on the effectiveness of the previous shock wave control and arc stability research, the flow distance between the electrode and the edge of the downstream ceramic block is 15mm to 40mm, and in this case, 35mm is preferred.

[0044] Pressure sensors 3-1 and 3-2 (absolute pressure sensors, reference selection CYG41000T, response frequency>10kHz) respectively collect the pressure information of the upstream of the supersonic incoming flow and the wall pressure after the oblique shock wave, and transmit them to the closed-loop controller 5 as input signals; pressure sensor 3-1 is located upstream of the plasma actuator 2 (the specific position can be determined according to the actual control object size, and its flow position in this case is 35mm away from the leading edge of the plasma actuator 2), and is directly installed on the wall of the case model, and the static pressure of the incoming flow is measured through an air bleed hole with a diameter of 1mm; the pressure after the oblique shock wave is measured by connecting the pressure measuring hole on the dynamic shock generator 1 with the measuring hole on the model wall through an air bleed hose to measure the pressure after the shock wave, and is connected to sensor 3-2 to avoid interference with the rotation of the dynamic shock generator 1. The pressure measuring hole is located 15mm downstream of the rotating shaft of the shock generator 1.

[0045] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for closed-loop control of dynamic shock waves, based on an arc plasma exciter to control the dynamic shock waves induced by a dynamic shock generator, characterized in that: Along the airflow direction, a first pressure sensor is installed at an upstream position of the plasma actuator, and a second pressure sensor is installed at a preset position downstream of the shock wave generator shaft; The current shock wave intensity is determined by acquiring the measured values ​​of the first sensor and the second sensor, and the closed-loop controller monitors the switch state quantity of the plasma actuator and the theoretical value of the shock wave intensity in real time; According to the currently measured shock wave intensity, a closed-loop control is formed and the working parameters of the plasma actuator are adjusted in real time to achieve a stable control of the dynamic shock wave pressure ratio and reach the preset control target value; According to the current shock wave intensity, case logic judgment is performed to determine the working state and parameters of the plasma actuator. The case logic judgment method includes: Determine the set value π of the shock wave intensity control target d , to determine whether the current shock wave intensity is greater than the set value π of the control target d， If yes, the plasma actuator is adjusted to an on state and the working parameters of the plasma actuator are adjusted according to the current shock wave intensity; if no, the plasma actuator is adjusted to an off state; When the shock wave generator is turned on, determine whether the current shock wave intensity is less than the set value π of the control target d If so, the working parameters of the plasma actuator are adjusted according to the current shock wave intensity until they are equal to the set target value; The inviscid theoretical value of the current shock wave is obtained according to the current state of the dynamic shock wave generator, and it is judged whether the current shock wave intensity is less than the inviscid theoretical value, or when the plasma exciter is in the off state, if so, the plasma exciter is turned off. The introduction of the inviscid theoretical value can effectively ensure the self-consistency of the case judgment logic when the overshoot phenomenon occurs in the control process, and ensure the stable operation of the plasma exciter. Among them, when the plasma exciter is in the on state, the method for adjusting the power of the plasma exciter in real time is: Based on the measured values ​​p1 and p2 of the first pressure sensor and the second pressure sensor, the plasma exciter power (Parc) and the shock wave intensity difference ( = p 2 / p 1-π d ) and satisfy: in, π th is the inviscid theoretical value of the oblique shock wave pressure ratio in the current state, which is calculated based on the current dynamic shock generator angle; π d The target pressure ratio for shock wave intensity control is 1.52 during verification; K P is the proportional coefficient, with a value range of (0, 1]; The current pressure ratio of each control cycle p 2 / p 1 is the discrete sum of the differences from the target value; Represents the change in shock wave pressure ratio within a unit time step; When the angle of the dynamic shock wave generator is fixed, select K P is 0.05 or 1.0 to achieve closed-loop control of the oblique shock wave pressure ratio to the specified target.

2. The method according to claim 1, characterized in that The preset position of the second pressure sensor is 15mm-20mm downstream of the dynamic shock wave generator shaft.

3. A dynamic shock wave closed-loop control verification device, characterized in that: A plasma actuator and a dynamic shock wave generator are arranged in sequence along the airflow direction, a first pressure sensor is installed upstream of the plasma actuator, and a second pressure sensor is installed at a preset position of the dynamic shock wave generator; the position of the plasma actuator is adjustable; pressure signal acquisition and processing and plasma actuator working state and parameter adjustment are realized through a closed-loop controller, and its control method is as described in claims 1 to 2, and the device can be used to verify the feasibility of the method and the dynamic shock wave closed-loop control research.

Images