Apparatus and method for fixing knock wave curvature loss

Abstract

The application discloses a device and method for fixing the curvature loss of a detonation wave, which comprises an ignition section, a propagation section, an expansion section and a tail end cover. The ignition section, the propagation section and the expansion section are connected through connecting flanges and are bolted. The fixed flanges of the expansion section and the tail end cover are used for auxiliary support and installation. The ignition section is connected to the premixed gas ignition to generate a detonation wave, the detonation wave is stably propagated in the propagation section, and the cross-sectional area of the expansion section is expanded at a fixed ratio, so that the detonation wave is propagated in the channel at a fixed curvature loss. The curvature loss in the propagation loss of the detonation wave is fixed, other losses are ignored by improving the configuration, the purpose of quantitatively measuring the propagation loss is achieved, researchers can further construct the quantitative relationship between the propagation characteristics of the detonation wave and the loss, establish a theoretical model for guiding the stable propagation of the detonation wave in a combustion chamber, and promote the development of the detonation theory and the engineering application of the detonation engine.

Description

TECHNICAL FIELD

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

[0002] Detonation wave is a supersonic combustion wave coupled by shock wave and chemical reaction zone. Detonation combustion belongs to supercharged combustion, which has extremely high heat release rate. Compared with traditional propulsion system based on isobaric combustion, 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 power. Detonation engine includes pulse detonation engine, rotary detonation engine and oblique detonation engine. Although the working principles of these engines are different, obtaining stable propagating detonation wave is the prerequisite for normal operation of all detonation engines. However, in the actual application process, detonation wave is affected by non-ideal factors and will experience various losses in the propagation process, such as fluid boundary layer loss, lateral expansion loss and curvature effect. These losses can cause loss of detonation wave propagation speed and peak pressure, and even lead to decoupling and extinction of detonation wave, thereby affecting the stable operation of the engine. Therefore, it is crucial to study the propagation loss of detonation wave for the engineering development of detonation engine.

[0003] At present, the research on the propagation loss of detonation wave mainly faces two problems. Firstly, according to the traditional research method, it is impossible to quantitatively measure the loss of detonation wave in the experiment. Secondly, due to the limitation of the actual environment in the experiment, the verification of the related theoretical model lacks strong support.

[0004] In view of this, the present application aims to provide a method for studying the propagation loss of detonation wave. A new method is proposed from general to special, which uses a device with special geometric configuration to fix the curvature loss in the propagation loss and as much as possible to ignore other losses (such as boundary layer loss), so as to realize the purpose of measurable propagation loss. Then it is convenient for researchers to establish the quantitative relationship between the propagation characteristics of detonation wave and the loss, to establish the theoretical model for guiding the stable propagation of detonation wave in the combustion chamber, and to promote the development of detonation theory and the engineering application of detonation engine. SUMMARY

[0005] The present application provides a device and method for fixing the curvature loss of detonation wave, which can quantitatively measure the propagation loss of detonation wave in the experiment, and is convenient for researchers to obtain the correlation between the propagation characteristics of detonation wave and the loss, and to establish the design criteria for regulating the stable propagation of detonation wave in the combustion chamber of the engine.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] The ignition section and the propagation section, and the propagation section and the expansion section are sealed by positioning bosses, sealing grooves and sealing rings at the connecting flanges. The flanges are uniformly provided with through holes, and the flanges are tightly connected by bolts. The ignition section inlet / outlet holes are welded with straight-through connecting pipes, and a high-energy igniter is installed at the head of the ignition section for ignition initiation of the detonation wave. The Schelkin spiral is additionally installed in the ignition section to accelerate the development of the flame, and promote the deflagration to detonation transition (DDT). Then the detonation wave enters the propagation section, and the propagation section and the ignition section are both equal-section circular straight pipes. 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, and the detonation wave is judged to be stably propagated by comparing with the theoretical Chapman-Jouguet (CJ) speed. Finally, the detonation wave enters the expansion section, and the cross section of the expansion section has a fixed area expansion ratio, and the cross section radius follows a natural exponential growth relationship. Eight pressure sensors are uniformly distributed on the profile of the expansion section to measure the pressure signal of the detonation wave during the propagation in the expansion section. In addition, an air inlet hole is arranged at the tail of the expansion section for the input of inert gas. In order to facilitate the installation and fixation of the expansion section, a support module is additionally installed on the expansion section. The support module is divided into two parts, a fixed flange is arranged on the outside of the middle part of the expansion section, and is matched with the grooves of the upper clamp and the support two, so that the positioning and support are facilitated. The support two and the upper clamp are fastened by bolts. In addition, the support one is welded with the flange at the tail of the expansion section to assist in supporting the expansion section.

[0008] The detonation wave propagation loss research method is constructed by using the above-mentioned detonation wave propagation loss research device, and includes the following steps:

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

[0010] S2: When the pressure sensor detects that the detonation wave propagates to the tail of the propagation section, the condition should be stable propagation, if not, return to the previous step.

[0011] S3: The detonation wave propagates to the expansion section, and the propagation curvature of the detonation wave in the expansion section is constant due to the geometric configuration of the expansion section, and the curvature loss is also constant. The pressure sensors uniformly distributed along the pipe wall profile are used to observe the change of the pressure and the propagation speed in the propagation process, and then the change of the loss is obtained.

[0012] Compared with the prior art, the beneficial effects of the present application are:

[0013] 1. The present application provides a device for fixing the curvature loss of the detonation wave, which can quantitatively measure the propagation loss of the detonation wave in the experiment by means of the device compared with the traditional configuration.

[0014] 2、The application provides a method for fixing the curvature loss of detonation wave to study the propagation loss, compared with the traditional research method, the method determines the curvature loss based on the device geometry, ignores the loss in other propagation processes, restores the related simulation conditions of the theoretical model as much as possible, so as to quantitatively study the propagation loss.

[0015] 3、The application provides a device and method for fixing the curvature loss of detonation wave, compared with the traditional configuration, the device is more diversified in function, and the feature of quantitatively measuring the propagation loss of detonation wave can provide strong support for the verification of the related theoretical model. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0018] Figure 3 It is a schematic diagram of the ignition section and the sensor installation position of the propagation section.

[0019] Figure 4 It is a schematic diagram of the connection flange.

[0020] Figure 5 It is a schematic diagram of the expansion section sensor installation position and the sensor installation seat

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

[0022] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the accompanying drawings in the embodiments of the application. Obviously, the described embodiments are only some examples of the application, not all embodiments.

[0023] The application provides a technical solution as shown in Figure 1 . Figure 1The schematic diagram of the main structure of the present application is shown in the figure, the ignition section 10, the propagation section 9, the expansion section 8 and the end cover 6 are tightly connected through the connecting flange 2. The curvature of the expansion section 8 is processed according to the nonlinear equation: R=Aexp(Bx), wherein R is the radial cross-sectional radius of the expansion section along the axial end cover, 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. The area expansion ratio of the expansion section channel is fixed, which ensures the constant curvature loss in the steady propagation process of the detonation wave. The gas inlet hole 5 can be used for introducing the second gas such as inert gas for auxiliary experiments.

[0024] As shown in the figure, Figure 2 As shown in the figure, Figure 2 The schematic diagram of the support structure of the present application is shown in the figure, which is divided into two front and rear support modules. In the front support module, the fixed flange 7 of the expansion section 8 is matched with the support two 13 with a groove and the upper clamp 14, which facilitates positioning, installation and fixation. The upper clamp 14 and the support two 13 are fastened by bolts. In the rear support module, the support one 12 is welded with 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 one 12 and the support two 13 are all provided with triangular ribs to assist force bearing and support. At the same time, the setting of the support module makes the main structure of the present application keep horizontal.

[0025] As shown in the figure, Figure 3 As shown in the figure, the left side is the cross-sectional view of the ignition section, the high-energy igniter installation site 11 is located at the head of the ignition section 10, the high-energy igniter is placed in the high-energy igniter installation site 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 is changed from 5 Hz to 80 Hz, which meets the frequency requirement of the experiment. The gas inlet hole 1 is arranged near the head, which is convenient for gas extraction or input during the experiment. Along the axis to the connecting flange direction, the Schelkin spiral 19 is arranged near the gas inlet hole 1 inside the ignition section 10, which is used to accelerate the flame development and promote the transition from slow combustion to detonation. The right side is the schematic diagram of the sensor installation of the propagation section, two sensor installation sites 3 are equally distributed at the tail of the propagation section 9 along the axis, the sensor is directly matched with the sensor installation site 3, and is fastened and sealed through threads.

[0026] As shown in the figure, Figure 4 As shown in the figure, the figure is the cross-sectional view when the connecting flange is connected, the ignition section 10, 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 of the connecting flange 2, that is, double-layer sealing, the inner ring is provided with a positioning boss 16 to assist positioning, the boss front side is reserved with a sealing groove 17, a sealing ring is placed in the sealing groove 17, after the bolt cooperation, the sealing ring is pressed to fill the entire sealing groove, and the outer ring plane sealing is the same, so as to ensure the air tightness of the device.

[0027] As shown in the figure, Figure 5As shown, the left side is the assembly view 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 position 4 is uniformly distributed along the expansion section curve, which is convenient for collecting pressure signals. The pressure sensor is directly connected with the sensor mounting seat 18 through threads, and the sensor mounting seat 18 is connected with the sensor mounting position 4 through bolts, and a sealing groove is arranged at the connection to ensure the air tightness. The main reason for adopting the design of the sensor mounting seat 18 is that the curved surface and the sensor mounting position 4 are not easy to process, and at the same time, the size of the sensor is greatly different from the size of the expansion section 8, which is easy to produce processing error and difficult to ensure the air tightness of the device, and the fault tolerance is low. After the design of the sensor mounting seat 18, the air tightness of the device is ensured, and the fault tolerance is improved, which is convenient for subsequent rework and modification.

[0028] The method for researching the propagation loss of detonation wave by using the device for researching the propagation loss of detonation wave is adopted, and the method comprises the following steps:

[0029] S1: The combustible gas is introduced into the inlet hole 1, the device is filled with gas, the high-energy igniter is installed at the high-energy igniter installation position 11, the ignition is started, the flame development is accelerated through the Schelkin spiral 19 located in the ignition section 10, and the 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 mounting positions 3 distributed at the tail of the propagation section, and determines whether the detonation wave has been 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 the stable propagation has been achieved, the detonation wave enters the expansion section 8, and the propagation curvature of the detonation wave in the expansion section is constant due to the geometric configuration of the expansion section 8, and the curvature loss is also constant. The pressure sensor uniformly distributed along the pipe wall profile is used to observe the change of pressure and propagation speed in the propagation process, and then the change of the propagation loss is obtained.

Claims

1. An apparatus for fixing a shock wave curvature loss, characterized by The device is composed of an ignition section, a propagation section, an expansion section, connecting flanges between each section, and a tail end cover. The ignition section is composed of a premixed gas inlet and a high-energy igniter. The expansion section has eight sensor positioning bolt installation sites evenly distributed along the expansion curved surface. The curvature of the expansion section profile is based on a nonlinear equation: R = Aexp(Bx), where R is the radial cross-sectional radius of the expansion section along the axial tail end cover, A is the radial cross-sectional radius at the inlet of the expansion section, and B is a parameter related to the curvature of the detonation wave front. The area expansion ratio of the expansion section channel is fixed to ensure constant curvature loss during the steady-state propagation of the detonation wave. The entire experimental device is installed by relying on the middle fixed flange in cooperation with the upper clamp and support two, and by relying on the support one welded to the flange at the tail end of the expansion section. Both of them work together to provide support.

2. The apparatus of claim 1, wherein The ignition section has a high-energy igniter installed at the left end and an air inlet hole arranged on the left side of the circular tube wall to introduce the premixed gas. A Schelkin spiral is arranged inside the tube to assist in detonation.

3. The apparatus of claim 1, wherein Two sensor installation sites 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 stably to the tail of the propagation section.

4. The apparatus of claim 1, wherein Eight pressure sensor installation sites are equidistantly arranged along the nonlinear equation generated curve of the expansion section, which facilitates the collection of pressure signals and propagation speed of the detonation wave in the expansion section, analysis of the results, and verification of related models.

5. The apparatus of claim 1, wherein In the installation method of the sensors in the expansion section, the pressure sensor and the sensor mounting seat are threadedly connected and sealed, and then the sensor mounting seat and the sensor installation site of the expansion section are bolted together. The sealing groove of the sensor mounting seat is filled with a sealing strip, and after the bolt is tightened, the sealing strip fills the entire sealing groove.

6. The device for fixing the curvature loss of the detonation wave according to claim 1, wherein a double-layer seal is used at the flange connection, and a sealing groove is opened on the contact surface of the two flanges, wherein the outer side is a flat seal, the inner side is divided into male and female, one side is a positioning boss, and the other side is a recess. The depth of the recess 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 recess. The gap is matched according to the tolerance, so that the sealing strip fills the entire sealing groove after being pressed, and the sealing effect is enhanced.

7. The apparatus of claim 1, wherein Two support modules are provided, which are divided into two parts. A fixed flange is provided on the outside of the middle part of the expansion section, which cooperates with the recess of the upper clamp and support two for positioning and support. The upper clamp and support two are fastened by bolts. In addition, support one is welded to the flange at the tail end of the expansion section to assist in supporting the expansion section. Support one and support two are respectively provided with triangular ribs at an angle of 60° and 45° to the bottom edge to assist in force bearing and support. Holes are arranged at the bottom of the two supports with a certain size to facilitate fastening with the laboratory bench plate through bolts.

8. A method for studying the fixation of the curvature loss of the blast wave, constructed with the device for fixation of the curvature loss of the blast wave according to any one of claims 2-7, characterized in that The steps are as follows Composition: S1: Fill the gas through the air inlet hole at the head position of the ignition section. After the gas fills the entire device, ignite the high-energy igniter. After the Schelkin spiral flame is accelerated, a detonation wave is generated in the ignition section. S2: The case when the pressure sensor monitors the propagation of the detonation wave to the tail of the propagation section should be stable propagation, if not, 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 sensor uniformly distributed along the pipe wall contour is used to observe the change of pressure and propagation speed in the propagation process, and then the change of loss is obtained.

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