A Numerical Investigation of Supersonic Flow Around Aft Bodies


Book Description

A numerical investigation has been made for supersonic flow past a cylindrical aft body with and without base bleed and a cylindrical boat tail. Comparison was made to available experimental data. The effect of grid cell density and turbulence models were examined. The calculation of the base flow region was much more highly dependent on grid density that was the forebody or outer flow field Agreement between the numerical and experimental results improved with the inclusion of the base bleed.




A Numerical Investigation of Subsonic and Supersonic Flow Around Axisymmetric Bodies


Book Description

A computational fluid dynamics (CFD) approach to predicting high- speed aerodynamic flow fields of interest to the U.S. Army Research Laboratory (ARL) has been carried out The aerodynamic problems of particular interest are: (1) supersonic flow past the aftbody of projectiles with base mass injection, (2) supersonic flow past the M549 projectile, and (3) subsonic, transonic, and supersonic flow past an M864 projectile with base bleed and wake combustion. The commercially available FLUENT (Fluent, Inc. FLUENT. Version 5.1.1, Lebanon, NH, 1999.) CFD code was utilized. The computational effort supports an ongoing ARL- sponsored experimental investigation. Of particular interest in the present investigation is the careful characterization of the various turbulence models employed in the CFD code. Additionally, the ease of use and set-up as well as the computational time will be described. An experimental effort (Dutton, J. C., and A. L. Addy. 'Fluid Dynamic Mechanisms and Interactions Within Separated Flows'. U.S. Army Research Office Research Grant DAAH04-93-G-0226 and the Department of Mechanical and Industrial Engineering, University of illinois, Urbana-Champagne, Urbana, IL, August 1998.) consisting of detailed laser Doppler velocimeter (LDV), particle image velocimeter (PIV), and high-speed wall pressure measurements has been made in axisymmetric and planar subsonic and supersonic flows with embedded separated regions. The present work seeks to predict similar flow fields computationally and to address areas of agreement and disagreement.










A Numerical Investigation of Supersonic Jet Interaction for Finned Bodies


Book Description

A detailed numerical investigation of the interaction between a lateral jet and the external flow has been performed for a variety of missile body geometries. These include non-finned axisymmetrical bodies and finned bodies with either strakes or aft-mounted tail fins. The computations were performed at Mach numbers 2, 4.5, and 8. To obtain the numerical results, both Reynolds- averaged Navier-Stokes and Euler techniques were applied. The computational results were compared with results from a previously published wind tunnel study that consisted primarily of global force and moment measurements. The results show significant interactions of the jet-induced flow field with the fin surfaces, which produce additional effects compared with the body alone. In agreement with the wind tunnel study, in some cases the presence of lifting surfaces resulted in force and/or moment amplification of the jet interaction with the missile surfaces. The results indicate deamplification of the jet force at Mach 2 for all three bodies. Amplification of the jet force was also observed for high Mach numbers, particularly for the body with strakes. For the results examined here, there were only minor differences in the global force and moment predictions when viscous or inviscid techniques were used. The dependence of the interaction parameters on angle of attack and jet pressure was well predicted by both methods. The numerical techniques showed good agreement with the experiments at supersonic Mach numbers but only fair agreement for the hypersonic, Mach 8 case.