A steady oblique detonation wave cell structure measurement system and method

Abstract

The application discloses a kind of steady oblique detonation wave cell structure measurement system and method, including experiment cabin, in the both ends of experiment cabin respectively set into hole and exit hole, into hole and exit hole are set diaphragm for sealing experiment cabin, and pre-charge combustible gas in experiment cabin;Projectile launching device is set in one end of experiment cabin, for projectile is accelerated to target speed after from into hole is launched into experiment cabin, and projectile is ejected from exit hole, projectile with target speed is contacted with combustible gas in experiment cabin and detonation, and oblique detonation wave is induced to occur;Smoke trace plate includes multiple, be set in experiment cabin and distribute in the circumferential and / or axial of projectile into experiment cabin trajectory, the surface of smoke trace plate is contacted with the oblique detonation wave generated and is swept by flow and forms cell grid.The application can be adapted according to the characteristics of oblique wave flow field, and the accurate cell grid shape and size are captured by setting smoke trace plate.

Description

Technical Field

[0001] This invention relates to the field of detonation wave cell measurement technology, specifically to a stationary oblique detonation wave cell structure measurement system and method. Background Technology

[0002] Detonation waves are a physical phenomenon resulting from the coupling of a strong shock wave and a chemical reaction. They can propagate self-sustainingly through complex three-dimensional structures, known as cell lattices. The cell size λ is a crucial characteristic parameter of a gas mixture and a standard for assessing its detonation sensitivity. Furthermore, the critical dimensions of a detonation engine, other dynamic parameters during detonation wave propagation, the explosion limits, and the critical direct initiation energy can all be obtained by considering the cell size λ. Therefore, accurately acquiring the cell structure during stable detonation wave propagation and precisely measuring the cell size λ are essential for the design of detonation engines.

[0003] The cell structure of detonation waves is usually collected using the smoke trail method, which involves fumigating a polyester film with fine carbon particles and other combustion products. When the detonation wave sweeps across the film, a fish-scale-like cell structure is collected.

[0004] Existing detonation wave cell measurement methods mainly target self-sustaining detonation waves propagating in confined or free spaces. These methods involve installing pre-smoked smoke plates on the walls of the detonation test chamber, where the self-sustaining detonation wave washes over the smoke plates during the experiment, leaving cell structure records. However, for stationary oblique detonation waves, due to their uneven cell spatial distribution and the fact that existing measurement methods often involve directly igniting combustible gases in the space, it is impossible to guarantee that their position and propagation direction will stably sweep across the surface of the cell collection plate. Summary of the Invention

[0005] The purpose of this invention is to provide a stationary oblique detonation wave cell structure measurement system and method to solve the technical problem in the prior art, which is that existing measurement methods mostly involve directly igniting combustible gases in space, thus failing to guarantee that the position and propagation direction of the gases can stably sweep across the surface of the cell plate.

[0006] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0007] A system for measuring the cell structure of stationary oblique detonation waves includes:

[0008] An experimental chamber is provided with an inlet and an outlet at both ends, and diaphragms are provided on the inlet and outlet to seal the experimental chamber. Combustible gas is pre-filled into the experimental chamber.

[0009] A projectile launching device is installed at one end of the experimental chamber. It is used to accelerate the projectile to a target speed and launch it into the experimental chamber through the inlet. The projectile is also launched from the outlet. The projectile with the target speed comes into contact with the combustible gas in the experimental chamber and detonates, inducing the generation of a slanted detonation wave.

[0010] Smoke plates, including multiple ones, are disposed in the experimental chamber and distributed in the circumferential and / or axial direction of the trajectory of the projectile entering the experimental chamber. The surface of the smoke plate is ablated by the generated oblique detonation wave to form a cell.

[0011] In a preferred embodiment of the present invention, the smoke trail plate is installed in the experimental chamber by a support device, the support device being able to adjust the angle of the smoke trail plate relative to the trajectory.

[0012] As a preferred embodiment of the present invention, a buffer cavity is provided at one end of the experimental chamber, the projectile launching port of the projectile launching device is located in the buffer cavity, and there is a gap between the projectile launching port and the inlet hole;

[0013] The inlet and outlet are equipped with diaphragms in the initial state.

[0014] As a preferred embodiment of the present invention, the smoke stain plate includes an arc-shaped aluminum plate body, and the support device is provided on both sides of the arc-shaped aluminum plate body.

[0015] This invention provides a measurement method based on the aforementioned stationary oblique detonation wave cell structure measurement system, comprising the following specific steps:

[0016] Step 100: Install multiple arc-shaped smoke plates inside the experimental chamber using a support device, seal the inlet and outlet holes of the projectiles on the experimental chamber using a diaphragm, and then inject a mixture of hydrogen and oxygen with a mixing ratio of 3:1 into the experimental chamber.

[0017] Step 200: Accelerate the projectile to a speed greater than the CJ detonation velocity of the mixed gas using a projectile launching device, and launch it into the experimental chamber through the inlet of the experimental chamber to induce the combustible gas in the experimental chamber to generate an oblique detonation wave.

[0018] Step 300: Remove the smoke-stained plate that was ablated by the oblique detonation wave from the experimental chamber, and fix the surface of the smoke-stained plate with transparent polyurethane paint to obtain the cell image of the smoke-stained plate surface caused by the oblique detonation wave.

[0019] As a preferred embodiment of the present invention, the diameter of the inlet hole of the projectile in the experimental chamber shown is 60 mm, the thickness of the diaphragm at the inlet hole of the projectile is 15 μm, and the thickness of the diaphragm at the outlet hole of the projectile is 100 μm.

[0020] As a preferred embodiment of the present invention, an optical observation window is provided on the experimental chamber, and a laser shadow image acquisition device is provided on the optical observation window to acquire the flow field structure of the oblique detonation wave in the experimental chamber.

[0021] As a preferred embodiment of the present invention, two speed measuring stations with a gap are set in the experimental chamber, one of which is close to the optical observation window; the flight speed of the projectile is obtained by calculating the distance between the two speed measuring stations.

[0022] The trigger time of the laser shadow image acquisition device is determined based on the flight speed and the distance between the speed measuring station and the optical observation window.

[0023] As a preferred embodiment of the present invention, a plurality of pressure sensors are provided in the experimental chamber, the pressure sensors being used to acquire the initial pressure in the experimental chamber and the pressure changes in the experimental chamber during the generation of oblique detonation waves.

[0024] As a preferred embodiment of the present invention, it further includes a method for statistical analysis of the cell image of the acquired smoke trace plate, specifically including:

[0025] Select at least 50 different cell locations on the smoke trace plate to statistically analyze the cell scale along the ballistic direction and perpendicular to the ballistic direction;

[0026] Among them, the cell scale along the ballistic direction is the cell length, and the cell scale perpendicular to the ballistic direction is the cell width.

[0027] For a rhombus cell, the cell length is the component of the distance between the two vertices along the trajectory, and the cell width is the component of the distance between the two vertices perpendicular to the trajectory.

[0028] For a polygonal cell, each vertex of the polygonal cell is replaced with the four points that are furthest away from the trajectory and perpendicular to the trajectory. The length and width of the polygonal cell are the components corresponding to the four points in the direction along the trajectory and in the opposite direction perpendicular to the trajectory.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] This invention provides a measurement system that fills an experimental chamber with combustible gas and detonates it with a high-speed projectile to form a sloping wave, and acquires the cellular image of the sloping wave by setting smoke trail plates in the circumferential and axial range of the trajectory. The system can adaptively set the smoke trail plates according to the generated sloping wave flow field to capture the precise cellular shape and size. Attached Figure Description

[0031] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the cell width distribution in oblique detonation.

[0034] Figure 3 This is a schematic diagram showing the change in cell width with pressure during the experiment of stationary oblique detonation and straw hat-shaped oblique detonation in this measurement system.

[0035] The labels in the diagram represent the following:

[0036] 1-Experimental chamber; 2-Inlet; 3-Outlet; 4-Diaphragm; 5-Projectile launching device; 6-Smoke plate; 7-Support device; 8-Buffer chamber. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, this embodiment provides a stationary oblique detonation wave cell structure measurement system, including:

[0039] Experimental chamber 1 has an inlet 2 and an outlet 3 at both ends. A diaphragm 4 is installed on the inlet 2 and outlet 3 to seal the experimental chamber 1. Combustible gas is pre-filled into the experimental chamber 1. The combustible gas is a mixture of multiple components. Considering the two-stage chemical reactions of the multiple components in the mixture during the oblique detonation wave, the mixture mainly uses 8 components and is mainly for hydrogen-oxygen detonation, namely H2, O2, HO, H2O, H2O2, HO2, O and H.

[0040] The projectile launching device 5 is set at one end of the experimental chamber 1. It is used to accelerate the projectile to the target speed and launch it into the experimental chamber 1 through the inlet 2. The projectile is also launched out of the outlet 3. The projectile with the target speed comes into contact with the combustible gas in the experimental chamber 1 and detonates, inducing the generation of oblique detonation wave.

[0041] Smoke plates 6, including multiple ones, are arranged inside the experimental chamber 1 and distributed in the circumferential and / or axial direction of the trajectory of the projectile entering the experimental chamber 1. The surface of the smoke plates 6 is ablated by the generated oblique detonation wave to form a cell.

[0042] The experimental chamber 1 provided in this embodiment is an integral cavity structure. There are no partition-type structures within the cavity that generate the oblique detonation wave, the purpose of which is to allow the generated oblique detonation wave to spread as widely as possible within the circumferential range of the trajectory. This enables the construction of oblique detonation waves adapted to different shock wave structures and flow fields, and allows for the measurement and adjustment of the resulting cellular structure.

[0043] This allows for the provision of equipment that provides smoke trail plates at different axial and circumferential distances along the projectile trajectory, enabling full measurement of the cell state of the generated oblique wave at various stages, thereby reflecting the state of the oblique wave.

[0044] Furthermore, it is possible to use the same scene to control the multivariables of the cell that generates oblique wave booms, and the control parameters include, but are not limited to, the end structure, velocity and angle of the projectile, as well as the combination of the components of the combustible gas, the position and shape of the smoke trail plate, etc.

[0045] In the measurement system described in this embodiment, the increased compression of the projectile in the oblique wave generated by the detonation of combustible gas by a high-speed projectile accelerates the chemical reaction rate of the combustion wave. The increased compression of the projectile under different operating conditions also leads to the establishment of different combustion wave forms.

[0046] For conditions where the projectile velocity is greater than the CJ detonation velocity, an increase in projectile velocity or initial pressure will reduce the length of the induction zone. The combustion wave induced by the projectile will couple with the shock wave to form a detonation wave as the compression effect increases.

[0047] The order of coupling is related to the compression of the projectile. The enhanced compression during shock wave induced combustion will cause the combustion wave to couple at the head of the projectile to form an overdriven detonation wave. If it continues to enhance, it will couple at the downstream of the projectile to form a stationary oblique detonation wave.

[0048] There exists a straw hat-shaped oblique detonation as an intermediate state between shock wave induced combustion and stationary oblique detonation. For projectile velocities lower than the CJ velocity, the increased projectile compression causes shock wave induced combustion to transform into a detonation wave, but the detonation wave cannot be stationary, thus forming a detonation wave that initiates the projectile detonation.

[0049] In this embodiment, the smoke plate 6 is installed in the experimental chamber 1 by a support device 7. The support device 7 can adjust the angle of the smoke plate 6 relative to the trajectory. Specifically, the support device can be a simple sheet-like or rod-like support structure.

[0050] By using the lattice of oblique detonation waves presented on the smoke trace plate 6, the experimental measurement and analysis of the lattice structure and size of oblique detonation shear waves can be achieved.

[0051] Measurements of the wave cell of oblique detonation show that the wavefront propagation state of stationary oblique detonation differs when it is near and far from the critical state.

[0052] The higher initial pressure far from the critical state leads to a shorter induction zone and an increase in the number of transverse waves. Combustion instability also leads to the generation / merging of transverse waves, resulting in a polygonal lattice structure.

[0053] Near the critical state, the transverse waves are regular and few in number, forming a large-sized regular rhomboid lattice.

[0054] The cell size variation pattern reflects the change in the propagation state of the detonation wave. The cell size of the stationary oblique detonation wave decreases with increasing pressure, while the variation pattern of the sombrero detonation wave is the opposite.

[0055] Furthermore, in this embodiment, unsteady process numerical simulations of the critical process and initiation process of the projectile are carried out to verify the critical theory and analyze the initiation mechanism of stationary oblique detonation wave.

[0056] The applicability of criticality theory is related to the specific flow process and initiation process. Existing criticality theories are only applicable to specific wave surface flow processes and initiation processes.

[0057] Existing experimental methods for verifying the energy limitation theory and the dimensionless projectile diameter have shown their limitations. They are applicable to the initiation process dominated by projectile compression, i.e., when the quenching of the detonation wave near the projectile is determined by the expansion wave. In this embodiment, the dimensionless projectile diameter d / λ can be proposed separately in different critical theories, which is the ratio of the projectile diameter to the cell width in the critical state.

[0058] For an initiation process dominated by exothermic chemical reactions, the reason for the quenching of the detonation wave is that the enhanced back-diffusion effect of the chemical reaction cannot support the coupling of combustion and shock wave. In such cases, the chemical reaction process needs to be considered.

[0059] One end of the experimental chamber 1 is provided with a buffer cavity 8. The projectile launching port of the projectile launching device 5 is located in the buffer cavity 8 and there is a gap between it and the inlet hole 2. Specifically, the buffer cavity 8 can be a cylindrical cavity structure, and the cylindrical cavity structure is coaxial with the projectile launching port.

[0060] In the initial state, the inlet hole 2 and the outlet hole 3 are equipped with diaphragm sheets 4.

[0061] The smoke stain plate 6 includes an arc-shaped aluminum plate body, and support devices 7 are provided on both sides of the arc-shaped aluminum plate body.

[0062] This embodiment provides a measurement method based on the aforementioned stationary oblique detonation wave cell structure measurement system, including specific steps:

[0063] Step 100: Install multiple arc-shaped smoke plates inside the experimental chamber using a support device, seal the inlet and outlet holes of the projectiles opened on the experimental chamber using diaphragms, and then inject a mixture of hydrogen and oxygen or other mixed fuel gas with a mixing ratio of 3:1 into the experimental chamber.

[0064] Step 200: Accelerate the projectile to a speed greater than the CJ detonation velocity of the mixed gas using a projectile launching device, and launch it into the experimental chamber through the inlet of the experimental chamber to induce the combustible gas in the experimental chamber to generate an oblique detonation wave.

[0065] Step 300: Remove the smoke plate that was ablated by the oblique detonation wave from the experimental chamber, and fix the surface of the smoke plate with transparent polyurethane paint to obtain the cell image of the smoke plate surface caused by the oblique detonation wave.

[0066] The diameter of the inlet hole for the projectile in the experimental chamber shown is 60 mm, the thickness of the diaphragm at the inlet hole is 15 μm, and the thickness of the diaphragm at the outlet hole is 100 μm.

[0067] In this embodiment, an optical observation window can be provided on the experimental chamber, and a laser shadow image acquisition device can be installed on the optical observation window to acquire the flow field structure of the oblique detonation wave inside the experimental chamber.

[0068] The projectile's flight speed is obtained by setting up two spaced-apart velocity measuring stations inside the experimental chamber, with one station located near the optical observation window; the distance the projectile travels between the two stations is calculated.

[0069] The trigger time of the laser shadow image acquisition device is determined based on the flight speed and the distance between the speed measuring station and the optical observation window.

[0070] Multiple pressure sensors are installed inside the experimental chamber. These pressure sensors are used to acquire the initial pressure inside the experimental chamber and the pressure changes inside the experimental chamber during the generation of the oblique detonation wave. The purpose is to use the pressure sensors to measure the initial pressure of the gas mixture inside the chamber and the pressure changes after the oblique detonation wave is generated, so as the projectile velocity increases, the state of the induced combustion wave of the oblique detonation wave can be measured, as well as the length of the induced zone after the shock wave is generated.

[0071] It also includes statistical methods for the cell images of the acquired smoke-stained plates, specifically including:

[0072] Select at least 50 different cell locations on the smoke trace plate to statistically analyze the cell scale along the ballistic direction and perpendicular to the ballistic direction;

[0073] Among them, the cell scale along the ballistic direction is the cell length, and the cell scale perpendicular to the ballistic direction is the cell width.

[0074] For a rhombus cell, the cell length is the component of the distance between the two vertices along the trajectory, and the cell width is the component of the distance between the two vertices perpendicular to the trajectory.

[0075] For a polygonal cell, each vertex of the polygonal cell is replaced with the four points that are furthest away from the trajectory and perpendicular to the trajectory. The length and width of the polygonal cell are the components of the four points in the direction along the trajectory and in the opposite direction perpendicular to the trajectory.

[0076] Based on the measurement system in this embodiment, two smoke trail plates at different distances from the ballistic trajectory were set up in the same experiment, and the cell size at different positions of the oblique detonation wave was measured simultaneously.

[0077] The figures show the cell width and cell length measured on the smoke trace plate at different locations. The two connected points in the figure correspond to the measurement results at different locations under the same working condition.

[0078] The specific details of the oblique wave boom cell measured in the experiment based on this measurement system include:

[0079] Figure 2 Specifically, this is a histogram showing the distribution of cell widths in oblique detonation waves under different operating conditions. Figure 2 The left side shows the cell width distribution of stationary oblique detonation. Figure 2 The right side shows the width distribution of the straw hat-shaped oblique detonation cell.

[0080] The cell width of stationary oblique detonation decreases with increasing pressure, and its distribution range also decreases with increasing inflation pressure.

[0081] The minimum cell width of stationary oblique detonation under different pressures does not change significantly, while its maximum value decreases with increasing pressure. The cell width is relatively densely distributed near the average value (marked by the dashed line in the figure), and the relative frequency of the cell width distribution decreases as it deviates from the average value.

[0082] Figure 2 The results indicate that the distribution of cell width in the somnium-shaped oblique detonation is relatively concentrated under different pressures, and the cell width distribution on both sides of the average value is relatively uniform. The cell width in the somnium-shaped oblique detonation does not show a significant trend of change with pressure.

[0083] The cell widths of stationary oblique detonations and hat-shaped oblique detonations with different initial pressures show that the distribution patterns of the cell widths of stationary oblique detonation waves are different from those of hat-shaped oblique detonation waves.

[0084] The cell width of the stationary oblique detonation wave decreases with increasing initial pressure. As the pressure increases from 18.0 kPa to 30.0 kPa, the cell width decreases from 7.2 mm to 3.3 mm. Moreover, under lower pressure conditions, the cell width of the detonation wave is not only larger but also has a large standard deviation, indicating that the cell width changes continuously during the propagation of the detonation wave.

[0085] Figure 3 The cell widths of normal detonation waves with the same composition and the same inflation pressure were compared. The cell width of stationary oblique detonation waves was close to that of normal detonation waves with the same pressure, while the cell width of straw hat-shaped oblique detonation waves was much lower than that of normal detonation waves with the same inflation pressure.

[0086] However, at lower pressures, the chemical reaction induction zone is longer, and the cell structure of the normal detonation wave is a relatively regular rhombus shape. In contrast, the cell structure of the oblique detonation wave under the same inflation pressure is different from that of the normal detonation. The polygonal cell structure indicates that the propagation process of the oblique detonation shear wave is different from that of the normal detonation wave, and its propagation process is more chaotic.

[0087] The measurement system can provide experimental data on the variation of cell width in hat-shaped oblique detonation waves, which differs from that of stationary oblique detonation waves.

[0088] The experiment showed that the cell width gradually increased with increasing pressure. In the experiment, the initial pressure range was 10.3 to 15.1 kPa, and the cell width increased from 3.0 mm to a maximum of 10.1 mm.

[0089] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A measurement system for stationary oblique detonation wave cell structure, characterized in that, include: An experimental chamber (1) is provided with an inlet (2) and an outlet (3) at both ends of the experimental chamber (1). A diaphragm (4) is provided on the inlet (2) and the outlet (3) to seal the experimental chamber (1), and combustible gas is pre-filled into the experimental chamber (1). The projectile launching device (5) is set at one end of the experimental chamber (1) and is used to accelerate the projectile to the target speed and launch it into the experimental chamber (1) through the inlet (2). The projectile is launched from the outlet (3). The projectile with the target speed comes into contact with the combustible gas in the experimental chamber (1) and detonates, inducing the generation of oblique detonation wave. Smoke plates (6), including multiple ones, are disposed in the experimental chamber (1) and distributed in the circumferential and / or axial direction of the trajectory of the projectile entering the experimental chamber (1). The surface of the smoke plates (6) is ablated by contact with the generated oblique detonation wave to form a cell. The smoke plate (6) is installed in the experimental chamber (1) by a support device (7), and the support device (7) can adjust the angle of the smoke plate (6) relative to the trajectory. One end of the experimental chamber (1) is provided with a buffer cavity (8), the projectile launching port of the projectile launching device (5) is located in the buffer cavity (8), and there is a gap between it and the inlet hole (2); In the initial state, the inlet (2) and the outlet (3) are provided with diaphragms (4). The smoke plate (6) includes an arc-shaped aluminum plate body, and the support device (7) is provided on both sides of the arc-shaped aluminum plate body.

2. A measurement method based on the stationary oblique detonation wave cell structure measurement system according to claim 1, characterized in that, Including specific steps: Step 100: Install multiple arc-shaped smoke plates inside the experimental chamber using a support device, seal the inlet and outlet holes of the projectiles opened on the experimental chamber using diaphragms, and then inject a mixture of hydrogen and oxygen or other mixed fuel gas with a mixing ratio of 3:1 into the experimental chamber. Step 200: Accelerate the projectile to a speed greater than the CJ detonation velocity of the mixed gas using a projectile launching device, and launch it into the experimental chamber through the inlet of the experimental chamber to induce the combustible gas in the experimental chamber to generate an oblique detonation wave. Step 300: Remove the smoke-stained plate that was ablated by the oblique detonation wave from the experimental chamber, and fix the surface of the smoke-stained plate with transparent polyurethane paint to obtain the cell image of the smoke-stained plate surface caused by the oblique detonation wave.

3. The method for measuring the cell structure of a stationary oblique detonation wave according to claim 2, characterized in that, The diameter of the inlet hole for the projectile in the experimental chamber shown is 60 mm, the thickness of the diaphragm at the inlet hole is 15 μm, and the thickness of the diaphragm at the outlet hole is 100 μm.

4. The method for measuring the cell structure of a stationary oblique detonation wave according to claim 2, characterized in that, An optical observation window is provided on the experimental chamber, and a laser shadow image acquisition device is set on the optical observation window to collect the flow field structure of the oblique detonation wave inside the experimental chamber.

5. The method for measuring the cell structure of a stationary oblique detonation wave according to claim 4, characterized in that, The projectile's flight speed is obtained by setting up two spaced-apart velocity measuring stations inside the experimental chamber, with one station located near the optical observation window; the distance the projectile travels between the two stations is calculated. The trigger time of the laser shadow image acquisition device is determined based on the flight speed and the distance between the speed measuring station and the optical observation window.

6. The method for measuring the cell structure of a stationary oblique detonation wave according to claim 2, characterized in that, Multiple pressure sensors are installed inside the experimental chamber. These pressure sensors are used to acquire the initial pressure inside the experimental chamber and the pressure changes inside the experimental chamber during the generation of the oblique detonation wave.

7. The method for measuring the cell structure of a stationary oblique detonation wave according to claim 2, characterized in that, It also includes statistical methods for the cell images of the acquired smoke-stained plates, specifically including: Select at least 50 different cell locations on the smoke trace plate to statistically analyze the cell scale along the ballistic direction and perpendicular to the ballistic direction; Among them, the cell scale along the ballistic direction is the cell length, and the cell scale perpendicular to the ballistic direction is the cell width. For a rhombus cell, the cell length is the component of the distance between the two vertices along the trajectory, and the cell width is the component of the distance between the two vertices perpendicular to the trajectory. For a polygonal cell, each vertex of the polygonal cell is replaced with the four points that are furthest away from the trajectory and perpendicular to the trajectory. The length and width of the polygonal cell are the components corresponding to the four points in the direction along the trajectory and in the opposite direction perpendicular to the trajectory.

Images