Gun Barrel Research Articles

Rifle Shooting for Athletes With Vision Impairment: Does One Class Fit All?

Revised evidence-based classification criteria introduced for shooting for athletes with vision impairment (VI shooting) suggest that athletes with impaired contrast sensitivity (CS) and visual acuity (VA) should be eligible for inclusion in the sport but should all eligible athletes compete against each other in the same “class” or is more than one class necessary? Twenty-five elite VI shooting athletes took part in the study. Two measures of visual function were assessed under standardized conditions: VA (using an ETDRS logMAR letter chart, and/or a BRVT chart) and CS (using both a Pelli-Robson chart and a Mars number chart). Shooting performance, in both prone and standing events, was measured during an international VI shooting competition. Fourteen of the 25 athletes had measurable VA, and for CS, 8 athletes had measurable function with the Pelli-Robson chart and 13 with the Mars chart. The remaining athletes had function not numerically measurable by the charts and were considered to have no residual vision. There was no indication that shooting performance varied with visual function, and individuals that had residual vision had no advantage over those without vision for either prone or standing shooting. The modifications made to VI shooting, including the use of auditory tones to guide the gun barrel, appear to have successfully rendered the sport equitable for all eligible athletes. Only one class is necessary for athletes. An improved method of measuring CS in athletes with profound VI would be advantageous.

Numerical investigation of dynamic interaction with projectile and harmonic behaviour for T-finned machine gun barrels

Machine gun barrels differ from their rifle counterparts in terms of profile. To support high rates of sustained fire, machine gun barrels are made thicker in order to dissipate more heat and maintain their flexural rigidity and thus accuracy, but on other hand they also contribute in weight addition to weapon. This investigation deals with comparison between a conventional machine gun barrel and an improved innovative design having T-fins, both having same weight and chambered in 5.56 × 45 NATO ammunition, to compare their structural and harmonic characteristics which were parameterized by factors such as modal spectrum, directional deformation at muzzle ends during a single shot fire and harmonic behaviour at corresponding range of exciting frequencies. The solid models of both the barrels having same weight, were created using Solidworks. The continuous input data functions were generated by MATLAB using the field tested discreet data points. The generated velocity-distance functions were converted into time dependent functions using integration algorithms to calculate transient parameters such as time steps, excitation frequency range, angle of rotation of projectile and its angular velocity. The dynamic condition simulated the varying nature of forces due to eccentricity in projectile and this data was fed to a time step study using ANSYS transient structural work bench followed by modal and harmonic analysis. The results showed a significant reduction in muzzle end deformation which thus proved that the T-finned barrel, although had same weight as that of the conventional one, but had better structural and harmonic characteristics, and hence it would inherit better firing accuracy.

Generalized Plane Strain Study of Rotational Autofrettage of Thick-Walled Cylinders—Part II: Numerical Evaluation

The theoretical modeling of the rotational autofrettage of a thick-walled cylinder based on the generalized plane strain assumption has been presented in part I of the paper. In order to access the potentiality of the proposed theoretical model, the numerical evaluation of the analytical solutions is important. This part of the paper presents numerical evaluation of the generalized plane strain model for typical thick-walled cylinders. The residual hoop stress generated in the rotational autofrettage of a typical gun barrel is compared with the residual hoop stresses in the conventional hydraulic and swage autofrettage processes. Comparison shows that the rotationally autofrettaged gun barrel is capable of producing the same level of compressive residual hoop stress at the inner surface as that of the hydraulic autofrettage. In order to corroborate the analytical solution, a three-dimensional finite element method (3D FEM) analysis of the rotational process is carried out in ANSYS finite element package and the results are compared with the theoretical results. The comparison shows a good matching of the results between the theoretical evaluation and the 3D FEM analysis. Finally, a short feasibility analysis of the rotational autofrettage process of typical cylinders is carried out for the practical realization of the process.

Theoretical simulation of temperature distribution in a gun barrel based on the DPL model

Theoretical simulation of temperature distribution in a gun barrel based on the DPL model

Investigating T-finned Barrels for Machine Guns: Enhancement in Heat Dissipation and Flexural Rigidity Along with Weight Reduction

This design innovation work is related to design and comparison of thermo-structural characteristics of a light-weight machine gun barrel. Compared to traditionally used thicker profile counter parts of machine gun barrels, these barrels were concluded to have lighter weight, better heat dissipation capability and better flexural rigidity. These barrels do not have rigidity problems like finned pencil barrels; neither have they extra weight addition, as in case of thicker profile barrels (H-Bars). To conduct the analysis, two same-length models of barrels bored for 5.56 × 45 mm, were modelled using Solidworks 15 software. The subsequent analysis using ANSYS 14.5 multi-physics solver simulated the condition of cook-off, which is an almost steady state reached after sustaining firing of 600 rounds (for 5.56 × 45 mm ammunition). It is a usual technical requirement expected from every durable machine gun, before the barrel is changed. The results showing maximum heat flux were transported to structural analysis workbench to measure the longitudinal deformation in both barrels under the gravity. The results concluded that T-finned barrels even after having less material, thus less weight, portrayed better heat dissipation characteristics and significantly less longitudinal deformation, thus better flexural rigidity and at the same time better accuracy retention than the conventional unfinned H-Bars.

Methodical approach to determine the dependence of the deviation of the initial speed of the shells through the extension of the charging chamber artillery guns, measured with the help of the instrument for measuring the chambers

The analysis results of the military use of artillery in the anti-terrorist operation in the east of the country indicate a significant amount of fire tasks, which relied on artillery and the high intensity of their implementation by artillery units, which negatively affected the technical condition of artillery systems. The monitoring of the technical state of the artillery armament of the Armed Forces of Ukraine indicates a sufficient degree of the trunk channels wearing out for a significant number of artillery systems, which directly affects the effectiveness of the fire tasks execution by artillery units.Due to the lack of artillery units provided by artillery ballistic stations, the determination of the change in the initial speed of the shells is usually carried out with the help of gunmeters, and not all artillery systems have tables of dependence on deflection of the initial speed of the projectiles due to the extension of the charging chamber. Taking into account the above, the question of determining the dependence of the deviation of the initial speed of the projectiles due to the extension of the charging chamber is a vital and important task. As an accessible method of determining deflection parameters of initial velocities of shells through the extension of the artillery gun charging chamber, a methodological approach with the use of internal ballistics tables is proposed.The basis of this approach is to take into account the effect of mechanical wearing out on the gun barrel channel to change the initial velocity of the projectile using known tabular dependencies. Input parameters of the methodical approach are: gauge caliber; coefficient of taking into account the depth of cuts; formular length of the charging chamber; volume of charging chamber; full path of the projectile by the trunk channel; the weight of the projectile; maximum pressure of powder gases; weight of powder charge.The proposed methodological approach is designed to improve the ballistic training activities carried out in artillery units and to develop dependency tables to determine the change in the initial velocity of the shells with the help of a gun measuring instrument for artillery systems.

Study on performance degradation and failure analysis of machine gun barrel

An increase in the use of the gun barrel will cause wear of the inner wall, which reduces the muzzle velocity and the spin rate of the projectile. The off-bore flight attitude and trajectory of the projectile also change, affecting the shooting power and the accuracy. Exterior ballistic data of a high-speed spinning projectile are required to study the performance change. Therefore, based on the barrel's accelerated life test, the whole process of projectile shooting is reproduced using numerical simulation technology, and key information on the ballistic performance change at each shooting stage are acquired. Studies have shown that in the later stages of barrel shooting, the accuracy of shooting has not decreased significantly. However, it is found that the angle of attack of the projectile increases as the wear of the barrel increases. The maximum angle of attack reaches 0.106 rad when the number of shots reaches 4300. Meanwhile, elliptical bullet hole has appeared on the target at this shooting stage. Through combining external ballistic theory with simulation results, the primary reason of this phenomenon is found to be a significant decrease in the muzzle spin rate of the projectile. At the end of the barrel life, the projectile muzzle spin rate is 57.5% lower than that of a barrel without wear.

Development of a technology for the surface strengthening of barrel channels in the large-caliber artillery guns

High temperatures and exposure to the chemical effect of powder gases that accompany artillery salvos actively destroy the surface layer of a barrel channel material. This disrupts the geometry of a barrel channel, thereby reducing the accuracy of an artillery gun aimed firing. We have proposed a technology of surface plastic deformation of the channel inner surface for strengthening the barrels of large caliber artillery and tank guns. The strengthening implies the cold-work hardening of a barrel channel metal with spherical deforming bodies that are mounted onto a massive cylindrical reinforcer. During machining, the reinforcer is driven into a rolling motion over the treated inner surface of a barrel channel and moves along the geometrical center of the machined gun’s barrel. As a result of such a hardening treatment, the residual compression stresses form in the thickness of a barrel channel material, thereby improving its surface microhardness. That contributes to an increase in the resistance of a barrel channel material against its burn-out and wear during artillery salvos.The reinforcing equipment for the implementation of such a treatment includes a reinforcer in the form of a cylinder with deforming bodies, an electric motor of the drive, and a mechanism to transfer the torque from the motor shaft to the reinforcer. During strengthening treatment, the set-up moves along a gun barrel channel, cold-working its material. The ensured hardening thickness is 0.15‒0.20 mm.The hardened surface layer of a gun barrel material, due to the heightened microhardness, firmly opposes the formation of operational microcracks within it. The compression stresses, formed in the thickness of a barrel channel metal, resist the temperature propagation of microcracks. Owing to this, the resistance of the hardened barrel metal against operational destruction increases, thereby improving the reliability and durability of costly artillery armament.

НЕКОТОРЫЕ АСПЕКТЫ ЭФФЕКТИВНОСТИ НАНЕСЕНИЯ АНТИФРИКЦИОННЫХ ПОКРЫТИЙ ТЕХНОЛОГИЯМИ ФИНИШНОЙ АНТИФРИКЦИОННОЙ БЕЗАБРАЗИВНОЙ ОБРАБОТКИ

The article analyzes the effectiveness of anti-friction coatings obtained by finishing anti-friction non-abrasive treatment (FANT), including processing in metal-clad technological media, in order to improve the performance of machine parts. The analysis of the application of coating technologies FANT on materials operating at elevated temperature and at high pressure, as well as with high values of energy fluxes in the environment, was carried out. The results of the application of various compositions of cladding elements and FANT technologies for various engineering products are presented. The results of studies of the use of FANT technologies developed with the participation of the authors confirm their high efficiency for improving the wear resistance of artillery gun barrel materials. Decrease in wear ranging from two to three times compare to regular technology. Field testing of anti-friction anti-wear coatings, carried out by specialists of the FSE SRI «Geodesia», confirmed the prospects of this direction for increasing the survivability of artillery barrels.

Main trends in development of heat treatment technologies of forged pipe shell for artillery barrels

Work purpose − to analyze conditions of operation of artillery system gun barrels, to define major factors which reduce qualitative characteristics of metal at manufacture from it of an ingot, pipe preparation and gun barrels and also at their use. To define top trendsin the production technology of competitive artillery systems which are characteristic of development of artillery arms for the last 10 years, including in the conditions of Ukraine. Research techniques : analytical fitted also the experimental studies. Results of researchesshowed that carry to major factors which significantly increase operational firmness of gun barrels of artillery systems: threw use of qualitative, threw increase in tensile strength a gun barrel (proportional limit), use of the effective protective coating of a canal surface of a gun barrel which counteract acceleration of an erosion is reduced by a wear and a loss of strength threw gun barrel canal surfaces at increase in energy of powder charges. The scientific noveltyof results of researches is defined by parameters of technologies of a heat treatment (preliminary for the deformed tubing stocks and finishing for ready gun barrels) and design process parameters of a hardening equipment which provides ≥ 140 kgf/mm2 (1 400 MPa) in metal of gunbarrels of level of a proportional limit and also parameters technologists and the equipment for drawing a layer of the protective coating (chromic, tantalic or other) method of a physical deposition from a gas phase of PVD (physical vapor deposition) on a canal surface that allows to receive the rated operational firmness of barrels of artillery systems (to the level of requirements of the countries of NATO). The practical significanceof results of researches consists in industrial approbation of developments and a possibility of their use during creation of industrial capacities for manufacture of competitive products which are able to provide requirements of army and export of these products on foreign market.

Development and modeling of a device for strengthening the channels of gun barrels by the method of vibration-centrifugal processing

The paper proposes a fundamentally new method of vibration-centrifugal hardening of internal cylindrical surfaces of long-length steel parts, in particular artillery guns, belonging to a group of methods of surface plastic deformation, and is characterized by providing a significant level of energy for deformation of the material being processed. Artillery cannons, along with a system for targeting shooting guns, are perhaps the most responsible component, which not only provides range and accuracy of the aiming shot, but also regulates the durability of the gun in general. During each of the gun shots, the surface layers of the metal of the channel of its trunk are exposed to the destructive effects of high (up to 10000 °C) temperatures, the chemical action of powder gases, excessive pressures and mechanical wear on the movement of the shell. This leads to the destruction of the structure, strength and density of the metal surface layers, its burning and wear, which in the rest, leads to violations of the geometry of the working surface of the trunk channel. Violation of the geometry of the working surface of the channel of the gun barrel negatively affects the range, and most importantly, the precision of gunfire and other precision related tactical and technical characteristics of gun armament. Excessively worn internal working surface of the canal of the trunk of repair and restoration is practically not subject. This determines the availability of such characteristics for cannon weaponry as the permissible number of gunfire shots, which to a certain extent limits the duration of the effective use of guns. A rather common practice in mechanical engineering is that when the strength characteristics and capabilities of the materials used are practically exhausted, designers and developers draw their views on the technological capabilities to improve the operational properties of parts and units. Not the last position in their list is the reinforcing operations of the surface layers of the material of the details by various methods of surface plastic deformation, widely known in the literary primary sources under the acronym “PPE methods”. The common advantage of the best of a fairly wide variety of varieties (rolling, rolling, smoothing, blasting and vibrating processing, etc.) is that, without substituting the part for energy-intensive high-temperature heating, the strength characteristics and performance properties of the most loaded surface layers of the material of parts are improved. Accordingly, the use in manufacturing processes of the details of PPD methods helps to increase their reliability and longevity. The developed design of the reinforcement on the basis of the proposed method of vibration-centrifugal hardening treatment is used to strengthen the internal cylindrical channels of the trunk of large-caliber artillery cannons. The reinforcement is simple in structure, energy-saving, does not provide for the maintenance of highly skilled service personnel. The solid-state model of the device for the vibration-centrifugal hardening of the internal cylindrical surfaces of steel parts has been created

IMPROVING OF ELECTROMECHANICAL STABILIZATION SYSTEMS ACCURACY

Aim. Improving of accuracy parameters and reducing of sensitivity to changes of plant parameters for nonlinear robust tank main armament guidance and stabilization electromechanical systems based on synchronous motor with permanent magnets and vector control. Methodology. The method of multiobjective synthesis of nonlinear robust control by nonlinear tank main armament stabilization electromechanical system taking into account the elastic oscillations of the tank gun barrel as a discrete-continuous plant and with parametric uncertainty based on the multiobjective optimization. The target vector of robust control choice by solving the corresponding multicriterion nonlinear programming problem in which the calculation of the vectors of the objective function and constraints is algorithmic and associated with synthesis of nonlinear robust controllers and modeling of the synthesized system for various modes of operation of the system, with different input signals and for various values of the plant parameters. Synthesis of nonlinear robust controllers and non-linear robust observers reduces to solving the system of Hamilton-Jacobi-Isaacs equations. Results. The results of the synthesis of a nonlinear robust tank main armament guidance and stabilization electromechanical systems are presented. Comparison of the dynamic characteristics of the synthesized tank main armament stabilization electromechanical systems showed that the use of synthesized nonlinear robust controllers allowed to improve the accuracy parameters and reduce the sensitivity of the system to changes of plant parameters in comparison with the existing system. Originality. For the first time carried out the multiobjective synthesis of nonlinear robust tank main armament stabilization electromechanical systems. Practical value. Practical recommendations are given on reasonable choice of the gain matrix for the nonlinear feedbacks of the regulator and the nonlinear observer of the tank main armament stabilization electromechanical systems, which allows improving the dynamic characteristics and reducing the sensitivity of the system to plant parameters changing in comparison with the existing system.

포신의 고각과 방위각 오차 최소화를 위한 차륜형 전투차량의 최적설계

포신의 고각과 방위각 오차 최소화를 위한 차륜형 전투차량의 최적설계

Warm-particle peening assisted HVOF spraying: A new process to improve the coating performances

In order to improve the coating quality to a higher level, a method of warm-particle peening assisted thermal spraying was put forward. This work presents a study based on a warm-particle peening assisted high-velocity oxy-fuel (WPPA-HVOF) spray system, in which the spraying powder was injected from the port near the gun nozzle throat and the peening media was injected from the port outside the gun barrel exit. A type of FeBSiNb amorphous coating was prepared by the WPPA-HVOF process and compared with that of the traditional HVOF process. The in-flight particle velocity and temperature were tested using a high-speed thermal spray process monitoring system, which manifests that the velocity and temperature of the awaiting deposit powder are hardly affected by the addition of peening particles. Through characterization of the deposit by methods such as SEM, EDS, and FIB, it was found that the peening particle is rebounded after impacting on the substrate. As a result, there were no peening particles mingled in the deposited coating even when the feed rate was as high as 140 g/min. A by-product is that the coating structure becomes dense, e.g. the porosity can be as low as 0.7%. The WPPA-HVOF process results in a decrease in coating surface residual stress to compressive state. The properties such as microhardness, cohesive strength and wear resistance increase to varying degrees consequently. It is hypothesized that this is attributed to the large compressive residual stress because of warm-particle peening during the deposition process.

The Study of Gun Barrel’s Two-Dimensional Nonlinear Thermal Conduction

In order to improve the life of gun barrel influenced by periodic transient thermal shock during firing, it is necessary to establish the heat conduction model of gun barrel to study the temperature field and its variation rule. Therefore, a mathematical model of two-dimensional nonlinear heat conduction is established. The governing equations and boundary conditions are linearized by Kirchhoff’s variation, and the finite difference equations of internal nodes and boundary nodes are derived using energy balance method and alternating difference implicit scheme. Based on the numerical results of the classics interior ballistic, temperature distribution of some 12.7 mm machine gun barrel during 120 successive firing rounds under the firing specification of the GJB3484-98 is calculated numerically. The temperature field of the external surface of the barrel is tested and the variation law of the temperature field is obtained. Comparison with experimental results shows good agreement with the simulation. The research results provided scientific basic for the studies of new barrel materials and coatings.

Strain Hardening and Strain-Rate Effect in Friction Between Projectile and Barrel During Engraving Process

The engraving of projectile is of great importance during interior ballistics when a gun is fired. In order to investigate the effect of loading speed on the engraving process, quasi-static and dynamic engraving tests are performed, respectively. Small caliber projectiles were engraved by using an MTS809 under predetermined low loading speeds and a specially designed gas gun-based test rig under high loading speeds. The hoop strain of the exterior surface of gun barrel during engraving process was measured. Surface morphology of copper jacket after engraving was observed. Microstructural evolution in cross section of copper jacket was investigated. The present study demonstrates the critical role of strain hardening at low loading speeds and strain rate effect as well as thermal effect at high loading speeds during the engraving process.

Numerical Modeling of Heat Transfer in Gun Barrel with Experimental Validation

Transient heat transfer in a gun barrel has been investigated numerically in this paper. Numerical modeling is conducted with the objective to obtain temperature history of the gun barrel. From the temperature history, the maximum number of gun shots before the cook-off temperature of the gun barrel attained can be known. Gun barrel is a part of firearm functioned to control gas flow which is aimed to propel projectiles out of the barrel with high velocity. Each propelled projectile produces very high temperature caused by projectiles explosion and friction between projectiles and bore surface. If the temperature of the gun barrel reaches the cook-off temperature, the bore surface will be damaged. Heat conduction equation in cylindrical domain is used to model heat transfer inside the gun barrel. Numerical results are obtained by implementing the finite volume method. From the numerical simulations, we found that our numerical method has very small error compared to experimental data that are 1.68% and 0.95% for total heat transfer and maximum temperature of bore surface, respectively. Moreover, the maximum number of gun shots in order not to attain the cook-off temperature is 27 times with ten seconds per shot and rest time six seconds in every six gun shots. Â

The cumulative detrimental impact of pressure and autofrettage on the fatigue life of an externally cracked modern tank gun barrel

The fatigue life of an externally cracked modern tank gun barrel is controlled by the prevailing combined stress intensity factor (SIF) <em>K</em>_<em>IN</em>, which consists of two components:<em>K</em>_<em>IP</em>-the SIF caused by internal pressure; <em>K</em>_<em>IA</em>-the positive SIF due to the tensile residual stresses induced by autofrettage. <em>K_IA</em> values for a single external radial semi-elliptical crack originating at the outer surface of an autofrettaged gun barrel were calculated for a large number of crack configurations by Perl and Saley. In order to assess the combined effect of overstraining and the pressurizing of the barrel during firing, values of <em>K</em>_<em>IP</em>, the SIF caused by internal pressure, and those of <em>K</em>_<em>IN</em>, the combined SIF, are evaluated. The 3D analysis is performed using the finite element method (FEM) employing singular elements along the crack front. The novel realistic overstrain residual stress fields, incorporating the Bauschinger effect, for the three types of autofrettage, Swage, Hydraulic and Hill's, previously developed, are applied to the barrel. The RSFs are simulated in the finit element (FE) analysis using equivalent temperature fields. Values of <em>K</em>_<em>IP</em> and <em>K</em>_<em>IN</em> are evaluated for a typical barrel of radii ratio <em>R</em>_<em>0</em>/<em>R</em>_<em>i</em>=2, crack depths (<em>a/t</em>=0.005-0.1), crack ellipticities (<em>a/c</em>=0.2-1.0), and five levels of the three types of autofrettage, (<em>ε</em>=40%, 60%, 70%, 80%, and 100%). A detailed analysis of the effect of the above parameters on the prevailing SIF is conducted. All three types of autofrettage are found to have a detrimental effect on the barrel's fatigue life. However, the magnitude of life reduction is autofrettage-type dependent. In the case of external cracking, Hydraulic autofrettage is found to be somewhat superior to Swage autofrettage, and Hill's autofrettage is found to be non-realistic. Finally, the results accentuate the importance of the three dimensional analysis and the incorporation of the Bauschinger effect.

Study the Effect of Anisotropy of Elastic-Plastic Properties on Residual Stress Development in Autofrettage of Thick Cylinder

Thick-walled cylinders subjected to high internal pressure and/or elevated temperatures are widely used in the aircraft, defence, nuclear and chemical industries especially for military applications e.g. the gun barrel in a ballistic event. In the absence of residual stresses, cracks usually form at the bore where the hoop stress developed by the working pressure is highest. To prevent such failure and to increase the pressure-carrying capacity of the pressure vessel, autofrettage process is used. During autofrettage a plastic region within the thick wall of the pressure vessel is produced by loading the pressure vessel in the plastic domain. Upon unloading, a residual compressive hoop stress is established within the plastic zone. This residual compressive stress counters the tensile hoop stress introduced due to service loading, thereby reducing the overall tensile hoop stress at inner surface. Therefore, autofrettage is used to introduce advantageous favourable compressive residual hoop stress inside wall of a cylinder and result in an increase in the fatigue lifetime of the component. Several researchers have studied the autofrettaged cylinders, both analytically and FE simulation. In this paper, effect of orthotropic anisotropy in the material properties will be studied on the stress field generated in the autofrettaged cylinder. Anisotropy in the material properties may result due to manufacturing processes like extrusion or pilgering. Plastic deformation leads to the development of preferred orientation of grains in the components due to slip occurring only in preferred slip planes in a crystal especially in a HCP material like Zr 2.5%Nb. In this paper, a thick cylinder made from Zr 2.5% Nb is loaded till elasto plastic interface is achieved and then unloaded to study effect of anisotropy on the development of residual stresses. Two material models are considered in the analysis i.e. isotropic and anisotropic plastic behaviour. The effect of anisotropy on the residual stress is investigated.

Modeling for the Calculation of Interior Ballistic Velocity of Electromagnetic Rail Launch Projectile

Interior ballistics is of great importance to the study of gun barrels and projectiles. One of its important characteristics is velocity, which determines the firing capability of projectiles. Aiming at the interior ballistic velocity (IBV) of projectiles launched from electromagnetic (EM) rail, this paper has analyzed the differences in the mechanism between the EM rail gun and the traditional cannon. Based on some assumptions, the calculation formula of projectile EM force was gained with the time-frequency analysis method. Then, it built a simulation calculation model of IBV of the projectile. In addition, the use of the positioned data of the magnetic probe (B-dot probe), to obtain the displacement fitting matrix, leads to the establishment of an experimental fitting model of IBV of the projectile. With the plane EM rail launcher in our laboratory as an example, the above-mentioned two models are applied to analyzing the accelerated motion of the projectile in the chamber. The experimental fitting results are compared with the measured data and simulation results of the B-dot probe, which are basically consistent. Thus, it shows that the IBV's simulation model and the experimental fitting model have high reliability.