Author: Dixie M. Hisley
Publisher:
ISBN:
Category : Blast effect
Languages : en
Pages : 48
Book Description
Computational fluid dynamics is a tool which predicts the gas dynamics of blast problems of interest to the Army by solving a set of mathematical equations with a high-speed digital computer. The governing equations for the blast problems presented here are the two-dimensional unsteady Euler equations. The computations were performed on a Cray XMP/48 supercomputer by discretizing the Euler equations with an upwind, Total Variation Diminishing, finite volume, implicit scheme. Details of the scheme are presented in the paper. The algorithm is used here to provide gas dynamic information for a candidate large-scale blast simulator (LBS) concept. A growing need exists for nuclear blast survivability testing of tactical equipment. In order to meet this need, research is conducting into the design and operation of a Large-scale Blast Thermal Simulator, essentially a large multi-driver shock tube. Experiments with heated and unheated driver gas have been performed in a single driver, 1/67 scale model of the LB/TS design concept but without the thermal simulation (LBS). One dimensional calculations have been performed for the 1/67 scale LBS with useful results. However, the one-dimensional calculations have had limited success for accurately predicting the flow through the diverging portion of the LBS design because the flow in this region is multi-dimensional. The flow is multi-dimensional due to the rapid and large area change that exists in the diverging nozzle. The paper presents results which demonstrate the nature of fluid physics in the 1/57 scale LBS. (jhd).
Axisymmetric Calculations for the Large Blast/Thermal Simulator (LB/TS) Shock Tube Configuration
Author: Dixie M. Hisley
Publisher:
ISBN:
Category : Blast effect
Languages : en
Pages : 48
Book Description
Computational fluid dynamics is a tool which predicts the gas dynamics of blast problems of interest to the Army by solving a set of mathematical equations with a high-speed digital computer. The governing equations for the blast problems presented here are the two-dimensional unsteady Euler equations. The computations were performed on a Cray XMP/48 supercomputer by discretizing the Euler equations with an upwind, Total Variation Diminishing, finite volume, implicit scheme. Details of the scheme are presented in the paper. The algorithm is used here to provide gas dynamic information for a candidate large-scale blast simulator (LBS) concept. A growing need exists for nuclear blast survivability testing of tactical equipment. In order to meet this need, research is conducting into the design and operation of a Large-scale Blast Thermal Simulator, essentially a large multi-driver shock tube. Experiments with heated and unheated driver gas have been performed in a single driver, 1/67 scale model of the LB/TS design concept but without the thermal simulation (LBS). One dimensional calculations have been performed for the 1/67 scale LBS with useful results. However, the one-dimensional calculations have had limited success for accurately predicting the flow through the diverging portion of the LBS design because the flow in this region is multi-dimensional. The flow is multi-dimensional due to the rapid and large area change that exists in the diverging nozzle. The paper presents results which demonstrate the nature of fluid physics in the 1/57 scale LBS. (jhd).
Publisher:
ISBN:
Category : Blast effect
Languages : en
Pages : 48
Book Description
Computational fluid dynamics is a tool which predicts the gas dynamics of blast problems of interest to the Army by solving a set of mathematical equations with a high-speed digital computer. The governing equations for the blast problems presented here are the two-dimensional unsteady Euler equations. The computations were performed on a Cray XMP/48 supercomputer by discretizing the Euler equations with an upwind, Total Variation Diminishing, finite volume, implicit scheme. Details of the scheme are presented in the paper. The algorithm is used here to provide gas dynamic information for a candidate large-scale blast simulator (LBS) concept. A growing need exists for nuclear blast survivability testing of tactical equipment. In order to meet this need, research is conducting into the design and operation of a Large-scale Blast Thermal Simulator, essentially a large multi-driver shock tube. Experiments with heated and unheated driver gas have been performed in a single driver, 1/67 scale model of the LB/TS design concept but without the thermal simulation (LBS). One dimensional calculations have been performed for the 1/67 scale LBS with useful results. However, the one-dimensional calculations have had limited success for accurately predicting the flow through the diverging portion of the LBS design because the flow in this region is multi-dimensional. The flow is multi-dimensional due to the rapid and large area change that exists in the diverging nozzle. The paper presents results which demonstrate the nature of fluid physics in the 1/57 scale LBS. (jhd).
Performance and Predictions for a Large Blast Simulator Model
Author: D. M. Hisley
Publisher:
ISBN:
Category :
Languages : en
Pages : 65
Book Description
An attempt is made to verify the predictions from a l-D BRL Code against the flow from a complicated, non-straight shock tube configuration; the code then could be utilized for future Large Blast/Thermal Simulator (LB/TS) design and prediction of performance, The shock tube is a 1/37 scale, axisymmetric model following the design for a multi-driver large blast simulator (LBS) located at Centre d'Etude, Gramat, France. It is used to produce shock pressures from 3.1 to 31 psi (21 to 214 kPa) and characteristic decaying wave forms. The BRL code is a quasi-one-dimensional, adiabatic, inviscid, Eulerian computer algorithm. The code is described and some preliminary checks against related configurations are performed. Furthermore, the code uses the experimental tube geometry and run conditions to generate flow data for comparison with the experimental data. Additionally, parameter studies are done-necking down of nozzle throat at the diaphragm station, heating of the driver gas, temperature effect on driver due to pressurizing--to check their influence on the tube behavior. In general, computed blast wave forms as well as levels agree well with experiment except for the highest levels where head losses and real gas effects are more pronounced. With the natural-burst-of-diaphragm operation of tube, diaphragm blockage of the nozzle throat is a problem; temperature effects due to pressurizing of driver are not.
Publisher:
ISBN:
Category :
Languages : en
Pages : 65
Book Description
An attempt is made to verify the predictions from a l-D BRL Code against the flow from a complicated, non-straight shock tube configuration; the code then could be utilized for future Large Blast/Thermal Simulator (LB/TS) design and prediction of performance, The shock tube is a 1/37 scale, axisymmetric model following the design for a multi-driver large blast simulator (LBS) located at Centre d'Etude, Gramat, France. It is used to produce shock pressures from 3.1 to 31 psi (21 to 214 kPa) and characteristic decaying wave forms. The BRL code is a quasi-one-dimensional, adiabatic, inviscid, Eulerian computer algorithm. The code is described and some preliminary checks against related configurations are performed. Furthermore, the code uses the experimental tube geometry and run conditions to generate flow data for comparison with the experimental data. Additionally, parameter studies are done-necking down of nozzle throat at the diaphragm station, heating of the driver gas, temperature effect on driver due to pressurizing--to check their influence on the tube behavior. In general, computed blast wave forms as well as levels agree well with experiment except for the highest levels where head losses and real gas effects are more pronounced. With the natural-burst-of-diaphragm operation of tube, diaphragm blockage of the nozzle throat is a problem; temperature effects due to pressurizing of driver are not.
Performance Predictions for the Large Blast/Thermal Simulator Based on Experimental and Computational Results
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
Book Description
A computational study was performed with the BRL-Q1D code to determine the expected performance characteristics fo the proposed U.S. Large Blast/Thermal Simulator (LB/TS). This computational study complements an earlier experimental parametric study which was performed in the 25.4-cm shock tube located at the BRL. For the experiments, the BRL 25.4-cm shock tube was configured as a 1:57 scale, axisymmetric, single-driver model of the LB/TS. This report documents two computational parametric studies which were performed to determine the range of nuclear blast simulations available with the current LB/ TS design. The first parametric study s a comparison with existing experimental data to validate the computational model and to determine the limits of its accuracy. The second parametric study used the validated computational model to predict the operating range of the LB/TS design.
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
Book Description
A computational study was performed with the BRL-Q1D code to determine the expected performance characteristics fo the proposed U.S. Large Blast/Thermal Simulator (LB/TS). This computational study complements an earlier experimental parametric study which was performed in the 25.4-cm shock tube located at the BRL. For the experiments, the BRL 25.4-cm shock tube was configured as a 1:57 scale, axisymmetric, single-driver model of the LB/TS. This report documents two computational parametric studies which were performed to determine the range of nuclear blast simulations available with the current LB/ TS design. The first parametric study s a comparison with existing experimental data to validate the computational model and to determine the limits of its accuracy. The second parametric study used the validated computational model to predict the operating range of the LB/TS design.
Scientific and Technical Aerospace Reports
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1134
Book Description
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1134
Book Description
Computers in Engineering, 1993
Author: Fatih Kinoglu
Publisher:
ISBN:
Category : Computer-aided engineering
Languages : en
Pages : 798
Book Description
Publisher:
ISBN:
Category : Computer-aided engineering
Languages : en
Pages : 798
Book Description
Navier-Stokes Simulations of Unsteady Transonic Flow Phenomena
Author: Christopher Alexander Atwood
Publisher:
ISBN:
Category :
Languages : en
Pages : 152
Book Description
Numerical simulation of two classes of unsteady flows are obtained via the Navier-Stokes equations: a blast-wave/target interaction problem class and a transonic cavity flow problem class. The method developed for the viscous blast-wave/target interaction problem assumes a laminar, perfect gas implemented in a structured finite-volume framework. The approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order accurate time history of the interaction of blast-waves with stationary targets. The inviscid flux is evaluated using either of two upwind techniques, while the full viscous terms are computed by central differencing. Comparisons of unsteady numerical, analytical, and experimental results are made in two- and three-dimensions for Couette flows, a starting shock-tunnel, and a shock-tube blockage study. The results show accurate wave speed resolution and nonoscillatory discontinuity capturing of the predominantly inviscid flows. Viscous effects were increasingly significant at large post-interaction times.based systems ]
Publisher:
ISBN:
Category :
Languages : en
Pages : 152
Book Description
Numerical simulation of two classes of unsteady flows are obtained via the Navier-Stokes equations: a blast-wave/target interaction problem class and a transonic cavity flow problem class. The method developed for the viscous blast-wave/target interaction problem assumes a laminar, perfect gas implemented in a structured finite-volume framework. The approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order accurate time history of the interaction of blast-waves with stationary targets. The inviscid flux is evaluated using either of two upwind techniques, while the full viscous terms are computed by central differencing. Comparisons of unsteady numerical, analytical, and experimental results are made in two- and three-dimensions for Couette flows, a starting shock-tunnel, and a shock-tube blockage study. The results show accurate wave speed resolution and nonoscillatory discontinuity capturing of the predominantly inviscid flows. Viscous effects were increasingly significant at large post-interaction times.based systems ]
Government Reports Announcements & Index
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1146
Book Description
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1146
Book Description
Energy Research Abstracts
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 840
Book Description
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 840
Book Description
Government reports annual index
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1180
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 1180
Book Description
Energy Research Abstracts
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 532
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 532
Book Description