Device and method for fixing detonation wave curvature loss

Abstract

The invention discloses a device and method for fixing detonation wave curvature loss. The device comprises an ignition section, a propagation section, an expansion section and a tail end cover. And the ignition section, the propagation section and the expansion section are connected by bolts through connecting flanges. The fixing flange and the tail flange of the expansion section are used for assisting in supporting and mounting. Premixed gas is introduced into the ignition section for ignition to generate detonation waves, the detonation waves are stably propagated in the propagation section, the expansion ratio of the cross section area of the expansion section channel is fixed, and it is guaranteed that the detonation waves are propagated in the channel with fixed curvature loss. According to the method, the curvature loss in the detonation wave propagation loss is fixed, and the configuration is improved to ignore other losses, so that the purpose of quantitatively measuring the propagation loss is achieved, researchers can conveniently construct a quantitative relation between detonation wave propagation characteristics and the loss, a theoretical model for guiding stable propagation of detonation waves in a combustion chamber is established, and the detonation wave propagation loss is accurately measured. And the development of the detonation theory and the engineering application of the detonation engine are promoted.

Description

Technical Field

[0001] The invention relates to the field of detonation combustion, and in particular to a device and method for fixing the curvature loss of a detonation wave. Background Art

[0002] Detonation wave is a supersonic combustion wave strongly coupled by shock wave and chemical reaction zone. Detonation combustion belongs to supercharged combustion with extremely high heat release rate. Compared with the traditional propulsion system based on isobaric combustion, the power device based on detonation combustion has higher thermal cycle efficiency and simpler structure. In recent years, detonation propulsion has become a research hotspot and frontier in the field of aerospace propulsion. Detonation engines are divided into pulse detonation engines, rotating detonation engines and oblique detonation engines. Although their working principles are different, obtaining a stable propagation of detonation waves is the premise for the normal operation of all detonation engines. However, in the actual application process, detonation waves are affected by non-ideal factors and will experience various losses during the propagation process, such as fluid boundary layer loss, lateral expansion loss and curvature effect. These losses can all cause the loss of detonation wave propagation speed and peak pressure. In severe cases, it will cause the detonation wave to decouple and explode, thus affecting the stable operation of the engine. Therefore, studying the propagation loss of detonation waves is crucial to the engineering development of detonation engines.

[0003] Current research on the propagation loss of blast waves faces two main problems. First, based on traditional research methods, it is impossible to quantitatively measure the loss of blast waves in experiments. Second, due to the limitations of the actual environment in the experiment, there is a lack of strong support for the verification of relevant theoretical models.

[0004] In view of this, the present invention aims to propose a method for studying the propagation loss of detonation waves, and proposes a new method, from general to specific, using a device with a special geometric configuration, fixing the curvature loss in the propagation loss, and ignoring other losses (such as boundary layer losses, etc.) as much as possible, so as to achieve the purpose of measurable propagation loss. It is convenient for researchers to construct a quantitative relationship between the propagation characteristics of detonation waves and losses, establish a theoretical model to guide the stable propagation of detonation waves in the combustion chamber, and promote the development of detonation theory and the engineering application of detonation engines. Summary of the invention

[0005] The present invention provides a device and method for fixing the curvature loss of detonation waves, which can quantitatively measure the propagation loss of detonation waves in experiments, so as to facilitate researchers to obtain the correlation between the propagation characteristics of detonation waves and the loss, and to establish combustion chamber design criteria for regulating the stable propagation of detonation waves in engines.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The ignition section and the propagation section, as well as the propagation section and the expansion section are sealed by the positioning boss, sealing groove and sealing ring at the connecting flange. Through holes are evenly distributed on the flange, and the flanges are tightly connected by bolts. The inlet / outlet holes of the ignition section are welded straight through and then connected to the pipeline. A high-energy igniter is installed at the head of the ignition section to ignite the initial detonation wave. The Schelkin spiral is installed in the ignition section to accelerate the development of the flame and promote the transition from slow combustion to detonation (Deflagration to Detonation Transition, referred to as DDT). After that, the detonation wave enters the propagation section. Both the propagation section and the ignition section are circular straight pipes with equal cross-sections. In addition, two pressure sensors are distributed at the tail of the propagation section to measure the pressure signal of the detonation wave and estimate its propagation speed. By comparing with the theoretical Chapman-Jouguet (CJ) speed, it is judged whether the detonation wave has been stably propagated. Finally, the detonation wave enters the expansion section. The cross section of the expansion section has a fixed area expansion ratio, and its cross-sectional radius follows a natural exponential growth relationship. Eight pressure sensors are evenly distributed on the expansion section's contour line to measure the pressure signal during the propagation of the detonation wave in the expansion section. In addition, an air inlet is provided at the tail of the expansion section for the input of inert gas. To facilitate the installation and fixation of the expansion section, a support module is installed on the expansion section. The module is divided into two parts. A fixed flange is provided on the outer side of the middle of the expansion section to cooperate with the grooves of the upper clamp and the second support for easy positioning and support. The second support is fastened to the upper clamp by bolts. In addition, the first support is welded to the flange at the tail of the expansion section to assist in supporting the expansion section.

[0008] The above-mentioned device for studying the propagation loss of detonation waves is used to construct a method for studying the propagation loss of detonation waves, comprising the following steps:

[0009] S1: The gas is filled from the air inlet at the head of the ignition section. After the gas fills the entire device, the high-energy igniter ignites, and after being accelerated by the Schelkin spiral flame, a detonation wave is generated in the ignition section.

[0010] S2: When the pressure sensor detects that the detonation wave propagates to the tail of the propagation section, the situation should be stable propagation. If it is unstable, return to the previous step.

[0011] S3: The detonation wave propagates to the expansion section. Limited by the geometric configuration of the expansion section, the propagation curvature of the detonation wave in the expansion section is constant, and the curvature loss is also constant. The pressure sensors evenly distributed along the pipe wall profile are used to observe the changes in pressure and propagation speed during the propagation process, and then derive the changes in the loss.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The present invention provides a device for fixing the curvature loss of detonation waves. Compared with the traditional configuration, the device can be used to quantitatively measure the propagation loss of detonation waves in experiments.

[0014] 2. The present invention provides a method for fixing the curvature loss of detonation waves to study propagation loss. Compared with traditional research methods, this method determines the curvature loss based on the geometric configuration of the device, ignores and weakens the losses in other propagation processes, and restores the relevant simulation conditions of the theoretical model as much as possible, so as to quantitatively study the propagation loss.

[0015] 3. The present invention provides a device and method for fixing the curvature loss of detonation waves. Compared with the traditional configuration, the functions of this device are more diversified. The feature of quantitatively measuring the propagation loss of detonation waves can provide strong support for the verification of relevant theoretical models. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the main structure of the present invention.

[0017] Figure 2 It is a schematic diagram of the installation of the support structure of the present invention.

[0018] Figure 3 For the ignition section profile and propagation section sensor installation location.

[0019] Figure 4 It is a cross-sectional view of the connecting flange.

[0020] Figure 5 Cross-sectional view of the expansion section sensor installation position and sensor mounting seat

[0021] In the figure, 1-air inlet, 2-connecting flange, 3-sensor mounting position (sensor is directly installed), 4-sensor mounting position (sensor has sensor mounting seat), 5-air inlet, 6-end cover, 7-fixing flange, 8-expansion section, 9-propagation section, 10-ignition section, 11-high energy igniter installation position, 12-support one, 13-support two (with groove), 14-upper clamp (with groove), 15-laboratory fixed table, 16-positioning boss at the connecting flange, 17-sealing groove, 18-sensor mounting seat, 19-Schelkin screw. DETAILED DESCRIPTION

[0022] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some examples of the present invention, not all embodiments.

[0023] The present invention provides a technical solution: Figure 1 As shown, Figure 1The main structure diagram of the present invention is shown in FIG. 1 , wherein the ignition section 10, the propagation section 9, the expansion section 8 and the end cover 6 are tightly connected by the connecting flange 2. The curvature of the processing profile of the expansion section 8 (single side) is based on the nonlinear equation: R=Aexp(Bx), where R is the radial cross-sectional radius of the end cover of the expansion section along the axial tail, A is the radial cross-sectional radius at the entrance of the expansion section, and B is a parameter related to the curvature of the detonation wave surface. The area expansion ratio of the expansion section channel is fixed to ensure that the curvature loss during the steady-state propagation of the detonation wave is constant. The air inlet 5 can be used to introduce a second gas such as an inert gas for auxiliary experiments.

[0024] like Figure 2 As shown, Figure 2 This is a schematic diagram of the support structure of the present invention, which is divided into two front and rear support modules. In the front support module, the fixed flange 7 of the expansion section 8 cooperates with the support 2 13 with a groove and the upper clamp 14 to facilitate positioning, installation and fixation. The upper clamp 14 and the support 2 13 are fastened by bolts; under the rear support module, the support 1 12 is welded to the flange at the tail of the expansion section 8 to play a supporting role. The support frame and the bottom plate of the support 1 12 and the support 2 13 are both provided with triangular ribs to assist in force and support. At the same time, the setting of the support module keeps the main structure of the present invention horizontal.

[0025] like Figure 3 As shown, the left figure is a cross-sectional view of the ignition section. The high-energy igniter installation position 11 is located at the head of the ignition section 10. The high-energy igniter is placed at the high-energy igniter installation position 11. The ignition starts the detonation wave, and the high-energy igniter is connected to the ignition control system to control the ignition frequency. The frequency range varies from 5Hz to 80Hz, which meets the frequency requirements of the experiment. An air inlet 1 is set near the head to facilitate the extraction or input of gas during the experiment. Along the axis to the connecting flange direction, a Schelkin spiral 19 is set near the air inlet 1 inside the ignition section 10 to accelerate the development of the flame and promote the transition of the flame from slow combustion to detonation. The right side is a schematic diagram of the propagation section sensor installation. Two sensor installation positions 3 are equidistantly distributed on the coaxial line at the tail of the propagation section 9. The sensor directly cooperates with the sensor installation position 3 and is fastened and sealed by threads.

[0026] like Figure 4 As shown, the figure is a cross-sectional view of the connection at the connecting flange. The ignition section 10 and the propagation section 9, the propagation section 9 and the expansion section 8, and the expansion section 8 and the tail end cover 6 all adopt the setting at the connecting flange 2, that is, a double-layer seal is adopted. A positioning boss 16 is set on the inner ring to assist in positioning. The depth of the sealing groove 17 is reserved on the front side of the boss. A sealing ring is placed in the sealing groove 17. After the bolts are engaged, the sealing ring is pressurized to fill the entire sealing groove. The outer ring plane seal is the same, thereby ensuring the air tightness of the device.

[0027] like Figure 5As shown, the left side is the assembly diagram of the expansion section sensor mounting position 4 and the sensor mounting seat 18, and the right side is the sensor mounting seat. The sensor mounting positions 4 are evenly distributed along the expansion section curve, which is convenient for collecting pressure signals. The pressure sensor is directly connected to the sensor mounting seat 18 through a thread, and the sensor mounting seat 18 is connected to the sensor mounting position 4 through a bolt, and a sealing groove is set at the connection to ensure air tightness. The main reasons for adopting the design with the sensor mounting seat 18 are: the curved surface and the sensor mounting position 4 are not easy to process, and at the same time, the sensor size is too different from the expansion section 8 size, which is easy to produce processing errors, making it difficult to ensure the air tightness of the device, and the fault tolerance rate is low. After adopting the design of the sensor mounting seat 18, the air tightness of the device is ensured while the fault tolerance rate is improved, which is convenient for subsequent rework and modification.

[0028] A method for studying detonation wave propagation loss is constructed by using the above-mentioned device for studying detonation wave propagation loss, comprising the following steps:

[0029] S1: A combustible mixed gas is introduced into the air inlet 1, the gas fills the interior of the device, a high-energy igniter is installed at the high-energy igniter installation position 11, and a detonation wave is ignited to accelerate the flame development through the Schelkin spiral 19 located in the ignition section 10, and a detonation wave is generated in the ignition section 10.

[0030] S2: The detonation wave enters the straight circular tube propagation section 9, passes through the two sensor installation positions 3 distributed at the tail of the propagation section, and determines whether the detonation wave has stably propagated according to the peak pressure and propagation speed of the detonation wave measured by the sensor. If not, return to the previous step.

[0031] S3: If it is determined that stable propagation has occurred, the detonation wave enters the expansion section 8. Limited by the geometric configuration of the expansion section 8, the propagation curvature of the detonation wave in the expansion section is constant, and the curvature loss is also constant. The pressure sensors evenly distributed along the pipe wall profile are used to observe the changes in pressure and propagation speed during the propagation process, and then derive the changes in the propagation loss.

Claims

1. A device and method for fixing the curvature loss of a detonation wave, characterized in that The device consists of an ignition section, a propagation section, an expansion section, connecting flanges between the various sections, and a tail end cover. The ignition section consists of a premixed gas inlet and a high-energy igniter, and the expansion section has 8 sensor positioning bolt installation positions evenly distributed along the expansion surface. The installation of the entire experimental device relies on the middle fixed flange, the upper clamp, and the second support, and on the other hand, the support one welded by the flange at the tail end of the expansion section, both of which play a supporting role together.

2. A device for fixing the curvature loss of a detonation wave according to claim 1, characterized in that The ignition section has a high-energy igniter installed at the left end, and an air inlet is arranged on the left side of the circular tube wall to allow the premixed fuel gas to enter. A Schelkin spiral is arranged in the tube to assist in detonation.

3. A device for fixing the curvature loss of detonation waves according to claim 1, characterized in that Two sensor mounting positions are installed equidistantly along the axis at the end of the propagation section, which can be used to directly install pressure sensors to ensure that the detonation wave propagates in a steady state when it reaches the tail of the propagation section.

4. A device for fixing the curvature loss of detonation waves according to claim 1, characterized in that The curvature of the expansion section processing profile (one side) is based on the nonlinear equation: R = Aexp (Bx), where R is the radial section radius of the expansion section along the axial tail end cover, A is the radial section radius at the expansion section entrance, and B is a parameter related to the curvature of the detonation wave surface. The area expansion ratio of the expansion section channel is fixed to ensure that the curvature loss is constant during the steady-state propagation of the detonation wave.

5. A device for fixing the curvature loss of detonation waves according to claim 1, characterized in that Eight pressure sensor installation positions are equidistantly arranged along the curved edge generated by the nonlinear equation in the expansion section to collect the pressure signal and propagation velocity of the detonation wave in the expansion section, analyze the results, and thus calibrate the relevant models.

6. A device for fixing the curvature loss of detonation waves according to claim 1, characterized in that In the installation method of the expansion section sensor, the pressure sensor and the sensor mounting seat are matched and sealed with threads, and then the sensor mounting seat and the expansion section sensor mounting position are matched with bolts. The sealing groove of the sensor mounting seat has a built-in sealing strip. After the bolts are tightened, the sealing strip fills the entire sealing groove.

7. A device for fixing the curvature loss of detonation waves according to claim 1, characterized in that double-layer sealing is adopted at the flange connection, and a sealing groove is opened on the contact surface of the two connected flanges respectively, wherein the outer side is a flat seal, and the inner side is divided into male and female, one side is made into a positioning boss, and the other side is made into a groove, and the depth of the groove is the corresponding depth of the sealing strip plus the height of the positioning boss. When the two are matched, the width of the boss is equal to the width of the groove in design, and the gap is matched according to the tolerance, so that the sealing strip fills the entire sealing groove after being compressed, and the sealing effect is enhanced.

8. The device for fixing the curvature loss of detonation waves according to claim 1, characterized in that Two support modules are set up, which are divided into two parts. A fixed flange is provided on the outer side of the middle of the expansion section, which cooperates with the grooves of the upper clamp and the second support to facilitate positioning and support. Among them, the second support is fastened to the upper clamp by bolts; in addition, the first support is welded to the tail flange of the expansion section to assist in supporting the expansion section. Supports one and two are respectively equipped with triangular ribs at 60° and 45° to the bottom edge to assist in force and support. The bottom of the two supports is arranged with holes of a certain size to facilitate fastening with the laboratory table by bolts.

9. A method for studying fixed detonation wave curvature loss is constructed by using a device for fixing detonation wave curvature loss as described in claims 2-8, characterized in that , there are the following steps composition: S1: The gas is filled from the air inlet at the head of the ignition section. After the gas fills the entire device, the high-energy igniter ignites, and after being accelerated by the Schelkin spiral flame, a detonation wave is generated in the ignition section. S2: When the pressure sensor detects that the detonation wave propagates to the tail of the propagation section, the situation should be stable propagation. If it is unstable, return to the previous step. S3: The detonation wave propagates to the expansion section. Limited by the geometric configuration of the expansion section, the propagation curvature of the detonation wave in the expansion section is constant, and the curvature loss is also constant. The pressure sensors evenly distributed along the pipe wall profile are used to observe the changes in pressure and propagation speed during the propagation process, and then derive the changes in the loss.

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