Numerical experiments to integrate the Navier-Stokes equations /

A series of numerical experiments are described which solve for the time dependent flow field around a circular cylinder accelerated to supersonic speeds. The study is performed using a computer program developed by Scala and Gordon which models the full time-dependent Navier-Stokes equations. Results are presented for Mach two flow past a cylinder at freestream Reynolds numbers of 15.0, 46.8, 157.2, and 704.6, based on cylinder diameter. The numerical results are compared with analytical solutions and experimental measurements and the accuracy of the numerical results is discussed. These comparisons show where the author's numerical solutions of the Navier-Stokes equations fail to give accurate results."April 1972."Includes bibliographic references (pages 48-49).A series of numerical experiments are described which solve for the time dependent flow field around a circular cylinder accelerated to supersonic speeds. The study is performed using a computer program developed by Scala and Gordon which models the full time-dependent Navier-Stokes equations. Results are presented for Mach two flow past a cylinder at freestream Reynolds numbers of 15.0, 46.8, 157.2, and 704.6, based on cylinder diameter. The numerical results are compared with analytical solutions and experimental measurements and the accuracy of the numerical results is discussed. These comparisons show where the author's numerical solutions of the Navier-Stokes equations fail to give accurate results.RDT & E Project no. ;Mode of access: Internet

Flame spreading in small arms ball propellant /

The method of characteristics is used to obtain numerical solutions which described flame spreading in a bed of small arms ball propellant. The hyperbolic partial differential equations governing the gas flow include the effects of friction, convective heat transfer, area change and propellant burning. Numerical results are presented for the temperature, velocity and pressure distributions during flame spreading in a venting bomb. The accuracy of the numerical results is discussed by comparison with experimental pressure measurements taken in propellant firings and with finite-difference solutions obtained by other investigations. (Author)."August 1972."Includes bibliographic references (page 42).The method of characteristics is used to obtain numerical solutions which described flame spreading in a bed of small arms ball propellant. The hyperbolic partial differential equations governing the gas flow include the effects of friction, convective heat transfer, area change and propellant burning. Numerical results are presented for the temperature, velocity and pressure distributions during flame spreading in a venting bomb. The accuracy of the numerical results is discussed by comparison with experimental pressure measurements taken in propellant firings and with finite-difference solutions obtained by other investigations. (Author).RDT & E Project no. ;Mode of access: Internet

The structure of three-dimensional separated flows in obstacle-boundary layer interactions /

The subject is investigated with flow visualization techniques; the turbulent boundary layer on the wall of a continuous supersonic wind tunnel is used. Sizeable separated flow regions can be studied since the wall width is 38cm and the boundary layer is typically 2.5cm thick. The large scale of the experiment is required to resolve the fine details of the flow structure. The flow visualization techniques are discussed. The structure of the separated flow upstream of the obstacle is seen to change with relatively small changes in Reynolds number R; the number of vortices varies from 6 to 4 to 2 as R changes. Data are presented for large and small protuberances, but the latter are emphasized."June 1975."Includes bibliographic references (pages 51-52).The subject is investigated with flow visualization techniques; the turbulent boundary layer on the wall of a continuous supersonic wind tunnel is used. Sizeable separated flow regions can be studied since the wall width is 38cm and the boundary layer is typically 2.5cm thick. The large scale of the experiment is required to resolve the fine details of the flow structure. The flow visualization techniques are discussed. The structure of the separated flow upstream of the obstacle is seen to change with relatively small changes in Reynolds number R; the number of vortices varies from 6 to 4 to 2 as R changes. Data are presented for large and small protuberances, but the latter are emphasized.RDT & E Project no. ;Mode of access: Internet

Turbulent boundary layers in blast wave and shock tube flows /

An unsteady boundary layer if formed along the ground as a result of nuclear explosions and large HE bursts. This boundary layer influences overturning vulnerability predictions for combat vehicles subjected to blast loading. An integral boundary-layer theory is used to predict the growth of the turbulent boundary layer behind a blast wave. Predictions are presented for conventional and nuclear yields ranging from 18100 kg (20 ton) to 9.07 x 10 to the 8th power kg (1 Mton) TNT equivalent. The boundary-layer growth is calculated using two techniques and compared with experimental boundary-layer measurements taken in a 90700 kg (100 ton) TNT surface tangent sphere explosion. One of the techniques, based on experimentally-derived values for shock position and velocity appears to give a reasonable estimate of the boundary-layer thickness based on the limited experimental data available for comparison. Shock tube simulation of blast wave boundary-layer effects is discussed. Estimates are presented for the growth of the wall boundary layer in the BRL 2.44m (8 ft) shock tube and the boundary layer that can be formed on a ground plane mounted in this shock tube. Testing in the wall boundary layer is not feasible because of balance response-time restrictions. It appears that blast wave boundary layers of moderate thickness, on the order of a meter or less can be simulated using the shock tube ground plane boundary layer. (Author)."August 1976."Includes bibliographic references (pages 53-54).An unsteady boundary layer if formed along the ground as a result of nuclear explosions and large HE bursts. This boundary layer influences overturning vulnerability predictions for combat vehicles subjected to blast loading. An integral boundary-layer theory is used to predict the growth of the turbulent boundary layer behind a blast wave. Predictions are presented for conventional and nuclear yields ranging from 18100 kg (20 ton) to 9.07 x 10 to the 8th power kg (1 Mton) TNT equivalent. The boundary-layer growth is calculated using two techniques and compared with experimental boundary-layer measurements taken in a 90700 kg (100 ton) TNT surface tangent sphere explosion. One of the techniques, based on experimentally-derived values for shock position and velocity appears to give a reasonable estimate of the boundary-layer thickness based on the limited experimental data available for comparison. Shock tube simulation of blast wave boundary-layer effects is discussed. Estimates are presented for the growth of the wall boundary layer in the BRL 2.44m (8 ft) shock tube and the boundary layer that can be formed on a ground plane mounted in this shock tube. Testing in the wall boundary layer is not feasible because of balance response-time restrictions. It appears that blast wave boundary layers of moderate thickness, on the order of a meter or less can be simulated using the shock tube ground plane boundary layer. (Author).RDT & E Project no. ;Mode of access: Internet

Characteristics of the sidewall and floor boundary layers in BRL supersonic wind tunnel no. 1 /

"December 1975."Includes bibliographical references (page 43).RDT&E :Mode of access: Internet

Parametric sensitivity study of a numerical model for flame spreading /

"October 1975."Includes bibliographical references (pages 26-27).RDT&E :RDT&E :Mode of access: Internet