• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.1
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• pp.24-30
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• 2024

The gas-gun test is a experimental approach employed to validate the operational or structural stability when subjected to the impact energy encountered during launch or target collision. Predicting the outcomes of the gas-gun test has traditionally relied on empirical knowledge, due to numerous factors such as the bird assembly's shape, weight, material, and flight velocity. However, due to the nonlinearity and complex interactions between these variables, numerous tests are necessary to identify the necessary requirements, resulting in significant expense and time consumption during the process. The objective of this study is to forecast the variations in impact energy in future tests by developing a numerical model and analysis that aligns with the test outcomes, utilizing the ABAQUS Explicit. The outcome of the numerical analysis produced a framework that anticipates the peak g and the duration of the actual gas-sun test results, throughout post-processing techniques using FFT and LPF filters.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.279-286
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• 2019

In this study, a numerical investigation is conducted for the shock deceleration prediction of a conical impactor in gas-gun tests. With the development of weapon systems, gas-gun tests are required to validate the survivability and structural reliability of devices under test (DUT) in high-G shock environments, such as those over ten thousand Gs or more. As shock endurance is highly influenced by various bird parameters, such as mass, velocity, and pressure, it is important to determine the appropriate test conditions to generate a high-G shock environment. However, experimental repetitive studies are inefficient to validate test conditions in terms of economic aspects. Therefore, a numerical technique is required to replace experimental gas-gun tests. Here, a numerical investigation is conducted with ANSYS AUTODYN using explicit code. Through this investigation, the dynamic behavior of DUT is presented. In addition, the results of numerical studies are verified through a comparison with the experimental results of a gas-gun test.

• Journal of Mechanical Science and Technology
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• v.18 no.10
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• pp.1819-1828
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• 2004

The purpose of this paper is to investigate the effects of slits and swirl vanes on the turbulence augmentation in the flow fields of a gun-type gas burner using an X-type hot-wire probe. The gun-type gas burner adopted in this study is composed of eight slits and swirl vanes located on the surface of an inclined baffle plate. Experiment was carried out at a flow rate of 450 ι/min in burner model installed in the test section of subsonic wind tunnel. Swirl vanes playa role diffusing main flow more remarkably toward the radial direction than axial one, but slits show a reverse feature. Consequently, both slits and swirl vanes remarkably increase turbulence intensity in the whole range of a gun-type gas burner with a cone-type baffle plate.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.389-396
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• 2002

In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.23-29
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• 2002

This paper is studied to investigate the effect of slits and swirl vanes on the main flow fields of a gun-type gas burner through X-Y plane and Y-Z plane respectively by using X-probe from hot-wire anemometer system. This experiment was carried out with flow rate $450{\ell}/min$ in respective burner models installed in the test section of a subsonic wind tunnel. The burner models with only slits and only swirl vanes respectively were made by modifying original gun-type gas burner. The fast jet flow spurted from slits played a role such as an air-curtain because it encircled rotational flow by swirl vanes and drives mixed main flow to axial direction. As a result, the gun-type gas burner had a wider flow range up to about Y/R=1.5 deviated from slits and maintains a comparatively large velocity in the central part of burner within the range of about X/R=2.5. Therefore, it was very desirable that swirl vanes were installed within slits in gun-type gas burner in order to control the main flow fields effectively.

• Journal of Powder Materials
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• v.21 no.1
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• pp.44-49
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• 2014

In this study, nanocrystalline nickel powders were cold compacted by a dynamic compaction method using a single-stage gas gun system. A bending test was conducted to measure the bonding strengths of the compacted regions and microstructures of the specimen were analyzed using a scanning electron microscopy. The specimen was separated into two parts by a horizontal crack after compaction. Density test shows that the powder compaction occurred only in the upper part of the specimen. Brittle fracture was occurred during the bending test of the compact sample. Dispersion of shock energy due to spalling highly affected the bonding status of the nanocrystalline nickel powder.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.145-150
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• 2003

The present study aims to optimize the performance of the Two-Stage Gas Gun by using the experimentally obtained data. RSM(Response Surface Method) was adopted in the optimization process to find the operating parameter than can maximize the projectile speed with the minimum number of tests. To decide the test points which results can consist of the response surface, 3$^{k}$ full factorial method was used, and the design variables were chosen with piston mass and 2$^{nd}$ driver fill pressure. The response surface was composed by nine test results and consequently the optimization was done with GENOCOP III, inherently GA code, in order to seek the optimal test point. The optimal test condition from the response surface was verified by the experiment. Results showed that the optimization process with response surface can successfully predict the test results fairly well. This study shows the possibility of performance optimization for the experimental facilities using numerical optimization algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.466-475
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• 2003

The gun-type gas burner adopted in this study is generally composed of eight slits and swirl vanes. Thus, this paper is studied to investigate the effect of slits and swirl vanes on the turbulent flow fields in the horizontal plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 $\ell$/min in the test section of subsonic wind tunnel. The axial mean velocity component in the case of burner model with only swirl vanes shows the characteristic that spreads more remarkably toward the radial direction than axial one, it does, however, directly opposite tendency in the case of burner model with only slits. Consequently. both slits and swirl vanes composing of gun-type gas burner play an important role in decrease of the speed near slits and increase of the flow speed in the central part of a burner because the biggest speed spurted from slits encircles rotational flow by swirl vanes and it drives main flow toward the axial direction. Moreover, the turbulent intensities and turbulent kinetic energy of gun-type gas burner are distributed with a fairly bigger size within X/R<0.6410 than burner models which have only slits or swirl vanes because the rotational flow by swirl vanes and the fast jet flow by slits increase flow mixing, diffusion, and mean velocity gradient effectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1299-1308
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• 2003

This paper is studied to investigate the effect of slits and swirl vanes on the development of turbulent flow fields in gun-type gas burner with a cone type baffle plate because this gas burner is generally composed of eight slits and swirl vanes. All of turbulent characteristics including mean velocities were measured in the horizontal plane and cross section by using X-type hot-wire probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 l/min in the test section of subsonic wind tunnel. Slits cause the fast jets, and then they have the characteristic that the flow is not adequately spread to radial direction and has long flow length and very small flow velocity distribution in the central part. On the contrary, swirl vanes does not have long enough for adequate flow length to downstream because the rotational flow diffuses remarkably to radial direction. However, the suitable arrangement between slits and swirl vanes causes effective flow width and flow length, and then it promotes fast flow mixing over the entire region including central part to increase turbulence more largely and effectively. Therefore, it is thought as a very desirable design method in gun-type gas burner to locate slits on the outside of swirl vanes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.774-781
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• 2018

In this investigation, a gas gun is proposed driven by carbon dioxide gas and installed on a quadcopter-type small unmanned drone for the purpose of cattle vaccination, and we developed a launcher and its connection unit. The system consists of a commercial drone, a gas gun, a solenoid valve, and the remote communication controller, etc. The velocity of launched projectile is measured, and the full system is finally validated through ground test and flight examination loaded for the real aircraft. The feasibility is checked if this technology is applicable to various disease abatement and hazard mitigation in the fields of agriculture and fire-fighting with the present research and development.