Gun Structure Research Articles

Study of the Propane Detonation Spraying under Different Gun Structures

Study of the Propane Detonation Spraying under Different Gun Structures

Research on the operation and quality control of small rock hole shotcrete robot

A small rock shotcrete robot is applied in the deep tunnel dynamic disaster physical simulation system in order to simulate the final operation process of the tunnel project. The robot’s spraying operation and control include many kind of factors. In this paper, the main parameters affecting the spraying operation are analyzed by establishing the spraying model and coating growth model. For matching reasonably the spraying parameters, the matching equation of spraying quality and spraying gun parameter model and spraying feed speed has been derived. Based on the matching equation, the spraying gun structure and robot control system are designed, and the spraying distance and spraying gun movement velocity including horizontal and vertical driving have been controlled better. On the basis of theoretical analysis, a small rock hole shotcrete robot prototype has been developed and the spraying experiments have been finished. The experimental results showed that the model and equation established can guided the spraying quality control. With the increase of the injection elevation angle, the length of the long and short axes of the elliptic coating becomes larger, and the average thickness of the coating center is between 2.23 and 2.34 mm, which meets the design index of the injection robot. The rock hole shotcrete robot meet the design requirements.

Investigation of Spindt Cold Cathode Electron Guns for Terahertz Traveling Wave Tubes

In this work, a Spindt cold cathode electron gun with a PPM (periodic permanent magnet) focusing system for a terahertz TWT (traveling wave tube) was designed and simulated based on the Pierce electron gun structure. More specifically, a new 3D (three dimensional) emission model was used, where the cathode radius of the electron gun was 1 mm and the cathode current was 30 mA, with an emitting half angle of about 28°. It was demonstrated that the electron beam was well focused with an electron beam radius of 0.3 mm and a filling ratio of 0.5 when the maximum value of the PPM field along with the axis was 0.122T. According to the simulation results, a planar cold cathode electron gun was developed. Measurements demonstrated that the I/V characteristics of the cold cathode gun were consistent with that of a cold cathode, revealing that the electrons emitted from the cathode are not intercepted when passing through the electron gun.

Design of the Sabot-Stopping System for a Single-Stage Light-Gas Gun for High-Velocity Impacts

Collisions of space debris and micrometeorites with spacecraft represent an existential hazard for human activities in near-Earth orbits. Currently, guidelines, policies, and best practices are encouraged to help mitigate further propagation of this space debris field from redundant spacecraft and satellites. However, the existing space debris field is an environment that still poses a great threat and requires the design of contingency and fail-safe systems for new spacecraft. In this context, both the monitoring and tracking of space debris impact paths, along with knowledge of spacecraft design features that can withstand such impacts, are essential. Regarding the latter, terrestrial test facilities allow for replicating of space debris collisions in a safe and controlled laboratory environment. In particular, light-gas guns allow launching impactors at speeds in the high-velocity and hypervelocity ranges. The data acquired from these tests can be employed to validate in-orbit observations and structural simulations and to verify spacecraft components’ survivability. Typically, projectiles are launched and protected using a sabot system. This assembly, known as a launch package, is fired towards a sabot-stopping system. The sabot separates from the rest of the launch package, to avoid target contamination, and allows the projectile to travel towards the target through an opening in the assembly. The response and survivability of the sabot-stopping system, along with the transmission of the forces to the light-gas gun structure and prevention of target contamination, is an important design feature of these test apparatuses. In the framework of the development of Malta’s first high-velocity impact facility, particular attention was dedicated to this topic: in this paper, the description of a novel sabot-stopping system is provided. The system described in this research is mechanically decoupled from the interaction with the impact chamber and the light-gas gun pump tube; this solution avoids damage in case of failures and allows easier operations during the pre- and post-test phases.

Research on Error Transfer Model and Simulation of Aircraft Gun Structure

In order to study the influence of structural motion and geometric error on the firing density during the firing of the aircraft gun, based on the multi-body dynamics theory, the structural topology of the aircraft gun was established, and the motion error coordinate relationship was constructed by the firing chain and the support chain of the aircraft gun. Establish motion transformation matrix and error transformation matrix between adjacent volumes. Further, the error transfer model of the aircraft gun firing process is constructed. The transmission law of the muzzle offset error caused during the firing of the aircraft gun is revealed. Then the model is simulated and analyzed, and the parameters such as test position error, motion error and muzzle vibration displacement under different firing rates are identified. Finally, the simulation results are compared with the experimental test results. The results show that the average error rate in the azimuth direction is 3.94%, and the average error rate in the pitch direction is 6.86%. The error rate in the pitch direction is significantly higher than that in the azimuth direction, and the measured offset values are higher than the simulated values, which verifies the validity and correctness of the model. It can meet the engineering design requirements and provide the basis for the structural design and optimization of the aircraft gun.

Influence of different pretreatments on the adhesion of nanodiamond composite films on Ti substrates via coaxial arc plasma deposition

In this study, we report on the novel growth of nanodiamond composite (NDC) films on titanium (Ti) substrates using the coaxial arc plasma deposition (CAPD) at room temperature, which offers several advantages over conventional growth techniques. CAPD employs a unique coaxial arc plasma gun structure that provides a supersaturated condition of highly energetic carbon ions (C+) for ultrafast quenching on the substrate, promoting the growth of nanodiamond grains. This allows for NDC films’ growth on diverse substrates without the need for initial seeding or substrate heating. However, the growth of NDC films on Ti substrates at room temperature is challenging due to the native oxide layer (TiO2). Here, we grew NDC films on Ti substrates using three different pretreatments: (i) hydrofluoric acid (HF) etching, (ii) insertion of a titanium carbide (TiC) intermediate layer, and (iii) in situ Ar+ plasma etching. The morphology and structure of the grown NDC films were examined by 3D laser, high-resolution scanning electron microscopies (HR-SEM), Raman, and x-ray photoelectron (XPS) spectroscopies. Our results demonstrate that in situ Ar+ plasma etching is the most effective pretreatment method for completely removing the native TiO2 layer compared to the other two ex situ pretreatments, in which re-oxidation is more likely to occur after these pretreatments. Furthermore, NDC films grown using the hybrid Ar+ ion etching gun (IG) and CAPD exhibit the highest sp 3 content (63%) and adhesion strength (16 N).

Investigation on co-disposal technology of sludge and municipal solid waste based on numerical simulation

Rapidly growing municipal sludge (sludge) with a low calorific value and high nitrogen content leads to high treatment difficulties. This study uses numerical simulations to simulate the steady-state combustion process of waste and sludge (40% moisture content) blending in a 750 t/d waste incinerator, to analyze the effect of sludge blending ratio on the combustion characteristics and to optimize the selective non-catalytic reduction (SNCR) spray gun structure. It was found that 13% is a suitable maximum sludge blending rate for the incinerator, satisfying the 3 T principle. Combining denitrification efficiency, NOx distribution uniformity, and modification feasibility, five spray guns are a more suitable SNCR solution with a denitrification efficiency of 45.40%. The results provide support and reference for the subsequent optimization of the working conditions of the waste incinerator and the optimal design of the incinerator.

A Novel Technique for Dynamic Analysis of an Electromagnetic Rail Launcher using FEM Coupled with Simplorer

The performance of a rail gun depends on the current density distribution over the rail and armature as it determines the force that accelerates the projectile of the rail gun. A finite element method (FEM) coupled with Simplorer was developed to model and study the performance of the rail gun. The rail gun was modeled using an ANSYS eddy current field solver to determine the current density distribution and equivalent rail gun circuit for the given rail gun geometry. The armature velocity was then calculated using Simplorer by coupling the obtained equivalent rail gun circuit and exciting the rails using a capacitor-based pulsed power supply (PPS) system. The FEM coupled with Simplorer method was verified by numerical calculations for the rectangular rails and also with other researchers’ value, and that showed a good agreement between the results. Further, the current density distribution over rails and armature and velocity of the armature was calculated for different rail cross sections such as circular concave, circular convex, rectangular concave, rectangular convex, T-shaped concave, and T-shaped convex with a C-shaped armature. It was observed that the circular convex rail gun with C-shaped armature showed minimum current density distribution and gives a higher value of armature velocity compared with other rail gun structures. Thus, the circular convex armature was found to be suitable for the electromagnetic (EM) rail gun launchingsystem.

Ballistic and Aerodynamic Characteristics Simulation for Trajectory Correction Projectile

Conventional ammunition easily deviates from the intended target. Its hit probability is reduced by such disturbance factors as fabrication errors, initial muzzle disturbance, initial velocity probable error, and stochastic wind effect. The effect of the above interference factors can be reduced by improving the shooting dispersion, ammunition, and gun or rocket engine structure. However, such improvements may fail to meet the operational requirements for modern warfare. Ballistic correction technique is a proposed trajectory control technique for precision strike with effective damage. Taking a 57mm calibre projectile as research object, trajectory correction projectile with different aerodynamic layouts were designed. The aerodynamic characteristic, static stability, exterior ballistic characteristic and firing density of each projectile has been studied through research method of theoretical analysis and numerical calculation. These findings are considered instrumental in the trajectory correction technology research and engineering application.

Experimental proof test of CW mode RF modulated grid-controlled thermionic electron gun

A CW mode RF modulated grid-controlled thermionic electron gun was proposed by Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS) for some high average current electron accelerators requirements. The RF modulated grid-controlled thermionic electron gun was selected for these purposes due to its simplicity and cost savings. The experimental proof test of this type electron gun was conducted. The RF power supply at 107.5 MHz for the grid modulation can be adjusted from 10 W to 70 W. The RF power is coupled into the gun of grid-cathode through a RF&DC modulator. The electromagnetic field and RF simulation of the modulator is presented here. The gun structure and the beam dynamics design are also shown in the paper. The cathode assembly and the electron guns are tested on a 10 kV test bench for beam characterization. The CW mode 107.5 MHz electron beam obtained from the proof test, which is important for future high average current electron injectors development.

Design and implementation of automatic painting mobile robot

Wall painting is a repetitive, stressful, and hazardous process that makes it an ideal automation case. In the automotive industry, painting had been automated but not yet for the construction industry. However, there is a strong need for a mobile robot that can move to paint residential interior walls. In this study, we aim to design and implement an automatic painting mobile robot. The conceptual design of the proposed wall painting robot consisting paint mechanism with a spray gun and ultrasonic sensor. The spray gun is attached to a pulley mechanism that has linear motion. The ultrasonic sensor is used to detect the spray gun when it reached a certain limit. The DC motor rotates clockwise and counterclockwise based on the ultrasonic sensor condition made. The experimental results indicate that the robot was able to paint the walls smoothly vertically, and horizontally. The spraying gun structure's speed is at a tolerable speed of 0.07 m/s, which could be increased, but to provide high-quality painting without any gaps, the current speed was selected as the most suitable, without any harm to the working process.

Design of a Double-Nozzle Air Spray Gun and Numerical Research in the Interference Spray Flow Field

Spray painting robots equipped with air spray guns have been widely used in the painting industry. In view of the low efficiency of single-nozzle air spray guns when spraying large targets, a new double-nozzle air spray gun structure was designed in this paper based on the Coanda effect of double jets. Firstly, a 3-D physical model of the double-nozzle air spray gun was built in Solidworks, in which unstructured grids were generated for the computational domain by ICEM. Secondly, the spray painting process was numerically modeled with the help of the computational fluid dynamics (CFD) software ANSYS-Fluent 16.0. The two-phase spray flow was calculated by coupling a discrete phase model (DPM) and the Taylor analogy breakup (TAB) method. The TAB model was applied to predict the secondary break-up. The DPM model was applied to predict the droplet trajectories. The geometry of an air spray gun has a significant influence on the spray flow field characteristics. The influence of the air spray gun geometry on the interference spray flow field characteristics and coating film thickness distribution were investigated by changing the values of the distance between the centers of the two paint holes (L) and the angle between the axes of the two paint holes (θ). Numerical results show that the smaller L and θ are, the stronger the interference effect between the two jets, while the more concentrated the paint is in the central region of the target surface, the easier it is for overspray to occur. With increasing L and θ, the interference effect gradually decreased and the extension distance of the coating film along the x-axis gradually increased. However, if L and θ are too large, the interference effect will become too weak and the shape of the coating film will become a concave, with more paint on both side regions and less paint in the central region, which will cause an uneven coating film. From the simulation results, it can be concluded that a more uniform coating film can be obtained when L = 30 mm and θ = 10°. The effective coating width of the double-nozzle air spray gun was increased by 85.7% compared with the single-nozzle air spray gun, which improved the spraying efficiency.

Optimisation of Energy Transfer in Reluctance Coil Guns: Application to Soccer Ball Launchers

Reluctance coil guns are electromagnetic launchers having a good ratio of energy transmitted to actuator volume, making them a good choice for propelling objects with a limited actuator space. In this paper, we focus on an application, which is launching real size soccer balls with a size constrained robot. As the size of the actuator cannot be increased, kicking strength can only be improved by enhancing electrical to mechanical energy conversion, compared to existing systems. For this, we propose to modify its inner structure, splitting the coil and the energy storage capacitor into several ones, and triggering the coils successively for propagating the magnetic force in order to improve efficiency. This article first presents a model of reluctance electromagnetic coil guns using a coupled electromagnetic, electrical and mechanical models. Four different coil gun structures are then simulated, concluding that splitting the kicking coil into two half size ones is the best trade-off for optimizing energy transfer, while maintaining an acceptable system complexity and controllability. This optimization results in robust enhancement and leads to an increase by 104 % of the energy conversion compared to a reference launcher used. This result has been validated experimentally on our RoboCup robots. This paper also proves that splitting the coil into a higher number of coils is not an interesting trade-off. Beyond results on the chosen case study, this paper presents an optimization technique based on mixed mechanic, electric and electromagnetic modelling that can be applied to any reluctance coil gun.

Research on muzzle response characteristics of automatic gun on launching based on rigid-flexible coupling dynamics

In order to study the important influence for firing dispersion of muzzle response of automatic gun on launching, the rigid-flexible coupling dynamics model of automatic gun was established based on the rigid-flexible coupling system dynamics theory in software RecurDyn. And the flexible body of gun barrel assembly was set up by the modal synthesis method of dynamic sub-structure. The Hertz contact theory and flexible Bushing forces model were made equivalent to these constrained joints. According to the characteristic of automatic gun structure and continuous launching load, the dynamic vibrating response of simulation and analysis was made for the automatic gun on launching. The muzzle vibration response displacements in vertical and horizontal direction were obtained in the 300 rate of fire. Then the muzzle vibration velocity and acceleration with different structure clearance were also calculated by the finite element analysis program of the rigid-flexible coupling dynamics model of automatic gun. Through the comparison and analysis, the numerical solutions are closely matched with the experimental results. The results show that the vertical angle error of firing dispersion is less than 3.8% and the horizontal angle error is less than 10.2%. Thus, the simulation and experimental results verify the correctness and feasibility of this model. Further the structure design and optimization of automatic gun can be provided a reference foundation.

Nonadiabatic Effects on Beam-Quality Parameters for Frequency-Tunable Gyrotrons

We propose an unconventional electron gun structure in which the emitter is located on a concave cathode surface with a non-uniform electric field. Such a design violates the intuition that an emitter should place close to a uniform electric field to reduce the velocity spread. The commonly employed design guide based on the adiabatic condition predicts a huge velocity spread of 24%, but the simulation using EGUN code and verified with CST particle studio shows a very low spread of 2.8%. Examining the magnetic moment and the kinetic energy of the beam reveals that the electrons experience a relatively long acceleration process due to the much weak electric field. That's why the non-adiabatic effect matters. In addition to the cyclotron compression and the E$\times$B drift, the "resonant" polarization drift plays a crucial role in reducing the overall velocity spread.Simulations show a decent beam quality with the pitch factor of 1.5 and the transverse velocity spread of 2.8% over a wide range of the magnetic field (7.4-8.0 T) and the beam voltage (12-22 kV) with a high structural tolerance. The promising results with the wide working range enable the development of continuous frequency-tunable gyrotrons.

Numerical Analysis of the Influence of Atmospheric Plasma Gun Structure on Plasma Flow

To investigate the gun structure influence on gas flow characteristics during plasma spraying process, a simplified 3-D computing model was developed to calculate the multi-physical properties of the gun. The geometric model included cathode and anode, and electrodes boundary layers. Besides the temperature of ions and electrons was treated separately. In other words, the model used a two-temperature plasma model, which took into account ionization and recombination reactions of ions and electrons, the plasma flow inside the spray gun was studied. From the calculation results, decreasing of gun throat diameter caused the increase of velocity and decreasing of temperature. The change of velocity behaved a linear relationship with diameters, while temperature decreasing slowed down when the diameters reached a certain value. The research will provide theoretical guidance for the optimal design of spray gun.

Practical design of triple junction for a 90 kV electron gun

High-voltage electron guns can commonly be damaged by surface flashover, which can occur across the insulator surface of the gun as a result of electron emission around the triple junction structure. Using secondary electron emission avalanche (SEEA) theory as a basis, the triple junction in a 90 kV electron gun is optimized in this work to avoid damage from the effects of surface discharges. A metal shielding structure is used to reduce the surface flashover caused by electron emission and ensure that the electron gun provides reliable high voltage performance. The aim of the proposed design method is to reduce the field strength that occurs within the electron gun structure. Simultaneously, it is shown that SEEA theory can provide a reasonable explanation for and a solution to the flashover phenomenon that occurs on the insulator surface. In addition, the metal shielding structure used to address the high voltage vacuum discharge phenomenon proves to be an effective design method. Experiments performed on the electron gun for a 90 kV X-ray tube demonstrate that the proposed design method has a favorable effect on control of the flashover phenomenon.

Conceptual study and design of A C-band photocathode injector

A C-band photocathode injector composed of a 3.6-cell C-band photocathode RF gun and two 1.8-m C-band accelerating structures is proposed. The injector is a low emittance electron source for free electron lasers (FEL) and other compact light sources. The RF structure of the cavities is designed with 2D SUPERFISH simulation. The beam dynamic study in ASTRA helps rectify the 2D RF simulation. To feed the cavities, a design of extracoaxial coupler with RF gun structure is presented. With compact focusing solenoids, for 0.25 nC bunch charge, the final energy can reach 6.9 MeV energy and the 95% emittance can be as low as 0.23 mm mrad (95%). All the details of RF design and beam dynamics studies are presented in this paper, and the design satisfied the requirements of FEL and other applications.

Numerical Analysis of Ar and Ar-H2 Atmospheric Plasma Spray With a Simplified Model

To study the difference of plasma spraying process between argon and argon-hydrogen working gas, a relative simplified fan-shaped numerical model of argon/argon-hydrogen atmospheric plasma spray process was set up to analyze the multi-physic field in the spraying gun. The model took electrodes especially cathode and anode boundary layers into consideration. In other words, a two-temperature plasma model was employed. With regard of both ionization and recombination of ions and electrons, their number density distributions, which are important to determine whether the injected particles are charged, were studied. The influence of secondary gas on plasma flow was investigated. According to the results, when adding hydrogen into the pure argon plasma, the temperature and velocity of the gas flow in spray gun chamber increased. The calculated results will provide theoretical guidance for the design and optimization of gun structure.

Effects of Tank Gun Structural Components on the First Shot Hit Probability

Fire power for a main battle tank is one of the most important performance parameters like survivability and mobility. Fire power effectiveness is directly related to the first shot hit probability, performance of main gun, second armament, gun and turret drive system, fire control system, automatic target tracker, commander and gunner sight etc. First shot hit probability (a measure of cumulative effects of errors) is affected by the variations of the projectile parameters, the main gun structure uncertainties, fire control system errors, interaction between the projectile and the gun barrel and the unpredictable environmental changes. These errors and variations can be eliminated or minimised by understanding and simulating the firing event properly, manufacturing the related parts in high precision, using advanced fire control algorithms, and accurate sensors. In this review study, the effects of main gun structural components on the first shot hit probability are investigated taking into account all of the associated error sources. In order for a main battle tank to have both high and repetitive first shot hit probability under all battlefield conditions the gun structure should respond in a similar manner in successive firings without causing any abrupt change in performance. In this study, first the dynamic behaviour of gun/projectile system is discussed and then the design recommendations for the main gun components such as bearings, gun barrel, recoil system etc. to achieve higher first shot hit probability are reviewed.