Numerical Modeling of Unsteady Gas Flow Around the Projectile in the Light Gas Gun

2004 ◽  
Author(s):  
Valery Ponyavin ◽  
Yitung Chen ◽  
Darrell W. Pepper ◽  
Hsuan-Tsung Hsieh
Keyword(s):  
Outer Surface ◽  
Gas Flow ◽  
Gas Gun ◽  
Gun Barrel ◽  
First Case ◽  
Tube Exit ◽  
Volume Method ◽  
Unsteady Gas Flow ◽  
Velocity Pressure ◽  
Launch Tube

In this study, an attempt to calculate the characteristics of gas flow around a projectile during the motion of the projectile in the Joint Actinide Shock Physics Experimental Research (JASPER) light-gas gun is undertaken. The flow is considered as axisymmetric, nonstationary, nonisothermal, compressible, and turbulent. For calculating the flow around the projectile, the finite volume method was employed. A comparison between two launch tube exit geometries was made. The first case was standard muzzle geometry, where the wall of the bore and the outer surface of the launch tube form a 90 degree angle. The second case included a 26.6 degree bevel transition from the wall of the bore to the outer surface of the launch tube. The results of the calculations are represented in figures depicting the flow at different moments of time. The figures show the fields of velocity, pressure and density, as well as the appearance of shock waves inside the geometry. Some comparisons with calculations of the same problem but using finite-element method were made. The obtained results can be further used for optimization JASPER geometry. The results also can be used for calculating the gun barrels for the strength and the oscillatory stability. In our future study we will couple structural analysis of the gun barrel material with the gas dynamic calculation of motion of the projectile in the gun barrel with the use of advanced computational methods.

Calculation of the Unsteady Gas Flow Around a Projectile Moving Through a Gun Barrel

2003 ◽  
Author(s):  
Valery Ponyavin ◽  
Roald Akberov ◽  
Yitung Chen ◽  
Hsuan-Tsung Hsieh ◽  
Darrell W. Pepper
Keyword(s):  
Shock Waves ◽  
Flow Pattern ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Gas Flow ◽  
Computational Domain ◽  
Gun Barrel ◽  
Volume Method ◽  
Unsteady Gas Flow ◽  
Velocity Pressure

The calculation of gas flow during the motion of a projectile in the gun barrel is a complicated computational task due of the presence of numerous factors, such as nonisothermicity, turbulence, changes in the shape of the computational domain with time, etc. In this study, an attempt to calculate the characteristics of gas flow around a projectile during the motion of the projectile in the gun barrel is undertaken. The flow is considered axisymmetrical, nonstationary, nonisothermal, compressible, and turbulent. For calculating the flow around the projectile, the finite volume method was employed. During the motion of the projectile, the flow pattern behind it changed from subsonic to supersonic. The results of the calculations are represented in figures depicting the flow at different moments of time. The figures show the fields of velocity, pressure and density, as well as the appearance of shock waves inside the gun barrel at subsonic and supersonic speeds.

2-D H-Adaptive Finite Element Method for Gas Gun Design

2003 ◽  
Author(s):  
Timothy T. deBues ◽  
Darrell W. Pepper ◽  
Yitung Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Outer Surface ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Gas Gun ◽  
First Case ◽  
Tube Exit ◽  
Launch Tube ◽  
Element Method

The Joint Actinide Shock Physics Experimental Research (JASPER) facility utilizes a two-stage light gas gun to conduct equation of state experiments. The gun has a launch tube bore diameter of 28 mm, and is capable of launching projectiles at a velocity of 7.5 km/s using compressed hydrogen as a propellant. A numerical study is conducted to determine the effects that launch tube exit geometry changes have on attitude of the projectile in flight. A comparison of two launch tube exit geometries is considered. The first case is standard muzzle geometry where the wall of the bore and the outer surface of the launch tube form a right angle. The second case includes a beveled transition from the wall of the bore to the outer surface of the launch tube. An h-adaptive, Petrov-Galerkin finite element method is employed to model the axisymmetric compressible flow equations. Numerical solutions indicate that pressure variations occur on the back face of the projectile from case to case.

scholarly journals Modelling of gas flow in shale using a finite volume method

2017 ◽  
Vol 49 ◽  
pp. 394-414 ◽  
Author(s):  
Piroska Lorinczi ◽  
Alan D. Burns ◽  
Daniel Lesnic ◽  
Quentin J. Fisher ◽  
Anthony J. Crook ◽  
...  
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Gas Flow ◽  
Volume Method

Linearized Theory of Supercavitating Hydrofoils in Subsonic Liquid Flow

1977 ◽  
Vol 99 (2) ◽  
pp. 311-318
Author(s):  
Tetsuo Nishiyama
Keyword(s):  
Incompressible Flow ◽  
Liquid Flow ◽  
Sound Speed ◽  
Gas Flow ◽  
Three Dimensional ◽  
Cavitation Number ◽  
Compressibility Effect ◽  
Linearized Theory ◽  
Velocity Pressure ◽  
Subsonic Region

In order to clarify the compressibility effect, the perturbed flow field of the supercavitating hydrofoil in subsonic region is examined by a linearized technique and, as a result, the general corresponding rule of the compressible flow to the incompressible one is proposed to obtain the characteristics of the supercavitating hydrofoil. The main contents are summarized as follows: (i) Basic relations between velocity, pressure, and sound speed are shown in subsonic liquid flow within the framework of linearization. (ii) The correspondence of the steady, characteristics of the two and three dimensional supercavitating hydrofoils in subsonic liquid flow to ones in incompressible flow is clarified. Hence we can readily calculate the characteristics by simple correction to ones in incompressible flow. (iii) Numerical calculations are made to show the essential differences of the compressibility effect between liquid and gas flow, and also the interrelated effect between cavitation number and Mach number on the characteristics of the supercavitating hydrofoils.

scholarly journals A Method for Generating Approximate Similarity Solutions of Nonlinear Partial Differential Equations

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mazhar Iqbal ◽  
M. T. Mustafa ◽  
Azad A. Siddiqui
Keyword(s):  
Gas Flow ◽  
Numerical Solutions ◽  
Nonlinear Partial Differential Equations ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Similarity Solutions ◽  
Standard Application ◽  
Approximate Similarity ◽  
Initial Boundary Value ◽  
Unsteady Gas Flow

Standard application of similarity method to find solutions of PDEs mostly results in reduction to ODEs which are not easily integrable in terms of elementary or tabulated functions. Such situations usually demand solving reduced ODEs numerically. However, there are no systematic procedures available to utilize these numerical solutions of reduced ODE to obtain the solution of original PDE. A practical and tractable approach is proposed to deal with such situations and is applied to obtain approximate similarity solutions to different cases of an initial-boundary value problem of unsteady gas flow through a semi-infinite porous medium.

Finite Volume Method for Modelling Gas Flow in Shale

2014 ◽  
Author(s):  
P. Lorinczi ◽  
A.D. Burns ◽  
D. Lesnic ◽  
Q.J. Fisher ◽  
A.J. Crook ◽  
...  
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Gas Flow ◽  
Volume Method

scholarly journals Dynamic Testing of Lime-Tree (Tilia Europoea) and Pine (Pinaceae) for Wood Model Identification

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5261
Author(s):  
Anatoly Bragov ◽  
Leonid Igumnov ◽  
Francesco dell’Isola ◽  
Alexander Konstantinov ◽  
Andrey Lomunov ◽  
...  
Keyword(s):  
Dynamic Testing ◽  
Model Identification ◽  
Uniaxial Stress ◽  
Compression Tests ◽  
Stress Strain ◽  
Kolsky Method ◽  
Gas Gun ◽  
Lime Tree ◽  
First Case ◽  
Wood Model

The paper presents the results of dynamic testing of two wood species: lime-tree (Tilia europoea) and pine (Pinaceae). The dynamic compressive tests were carried out using the traditional Kolsky method in compression tests. The Kolsky method was modified for testing the specimen in a rigid limiting holder. In the first case, stress–strain diagrams for uniaxial stress state were obtained, while in the second, for uniaxial deformation. To create the load a gas gun was used. According to the results of the experiments, dynamic stress–strain diagrams were obtained. The limiting strength and deformation characteristics were determined. The fracture energy of lime and pine depending on the type of test was also obtained. The strain rates and stress growth rates were determined. The influence of the cutting angle of the specimens relative to the grain was noted. Based on the results obtained, the necessary parameters of the wood model were determined and their adequacy was assessed by using a special verification experiment.

Nonisothermal Unsteady Gas Flow in a Coupled Reservoir-Wellbore System

1991 ◽  
Author(s):  
S.G. Dias ◽  
A.C. Bannwart ◽  
K.V. Serra
Keyword(s):  
Gas Flow ◽  
Unsteady Gas Flow

DSMC Simulation of Rarefied Gas Flow Over a Wall Mounted Cube

2019 ◽  
Author(s):  
Deepak Nabapure ◽  
Ram Chandra Murthy
Keyword(s):  
Gas Flow ◽  
Rarefied Gas ◽  
Flow Behavior ◽  
Direct Simulation Monte Carlo ◽  
Temperature Fields ◽  
Gas Flows ◽  
Rarefied Gas Flows ◽  
Dsmc Simulation ◽  
Recirculation Length ◽  
Velocity Pressure

Abstract The present study investigates the flow behavior of the rarefied gas over a wall-mounted cube. The problem is studied for different cube heights (h) of 9mm and 18mm in the slip and transition regimes. The Direct Simulation Monte Carlo (DSMC) method is employed to evaluate the properties such as velocity, pressure and temperature fields. The Reynolds number (Re) ranges from 403 to 807, and the Knudsen number (Kn) is in the range from 0.05 to 0.103. A typical shock wave is formed in front of the cube. The recirculation length of the vortices normalized with respect to the respective cube heights for Kn = 0.05 and Kn = 0.103 are about 1.11 and 1.95 respectively. Similarly, the center of the vortices is located at about 3.33 and 6.11 times the respective cube heights upstream, for Kn = 0.05 and Kn = 0.103. The local temperature and pressure variations observed upstream of the cube are two orders higher in magnitude and are primarily attributed to strong compressibility effects. The present study paves the way for benchmarking, and forms a basis for understanding the rarefied gas flows over complex geometries.

Transitional ballistics of electric high-velocity launchers

2019 ◽  
Author(s):  
B. Reck ◽  
S. Hundertmark ◽  
R. Hruschka ◽  
A. Zeiner ◽  
B. Sauerwein ◽  
...  
Keyword(s):  
High Velocity ◽  
Gas Flow ◽  
Mechanical Response ◽  
Numerical Models ◽  
Time Interval ◽  
Viscous Effects ◽  
Simulation Code ◽  
Package Design ◽  
Gun Barrel ◽  
Experimental Values

Abstract The high-velocity launch of a projectile is subjected to a number of disturbances which exert an influence on the flight trajectory. In the case of sub-caliber projectiles, sabot separation is one of the critical aspects. In this work, we focus on the projectiles and the launch package of an electric railgun launch, i.e. on the behavior of the launch-package, when transitioning from the gun barrel to free-flight. This work further addresses the use of a hydrocode for creating numerical models which are capable of predicting the motion and deflection of the sabot parts during their separation from the projectile after exiting the muzzle. An earlier study showed that the air flow around the projectile and the sabot can be modeled with sufficiently high accuracy by means of a simulation code that uses an Eulerian description of the gas flow. Within a time interval of several milliseconds, just the duration that a projectile needs to enter quasi-stationary flight, viscous effects of the air or gas flow have relatively little influence on the sabot discard process. If the Eulerian gas flow is coupled with the Lagrangian structural parts, the mechanical response of the latter to the gas pressure can be complex in terms of deformation and damage, and in that way, can affect the gas flow. In this study, the hydrocode model is applied to a medium caliber launch package concept for accelerating long rod projectiles. The computed results agree well with the corresponding experimental values obtained from a launch package model test in the shock tunnel at Mach 4.5. This demonstrates that the presented hydrocode model can be used for launch package design optimizations with high confidence.

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