Freestream

About: Freestream is a research topic. Over the lifetime, 3428 publications have been published within this topic receiving 56147 citations.

Comparative Study of Plasma Spray Flow Fields and Particle Behavior Near to Flat Inclined Substrates

Abstract: Numerical models have been developed using computational fluid dynamics (CFD) analysis program FLUENT V6.02© to investigate the effect of the substrate on the behavior of the plasma flow fields and in-flight particles. Simulations are performed for cases where flat substrates are either present or absent, for the former, the substrate is oriented perpendicularly or inclined to the torch axis. It is shown that although the presence of perpendicular or inclined substrate significantly influences the plasma flow fields at the vicinity of the substrate, the particle behavior remain relatively unaffected. The insignificant effect of the substrate on particle behavior is qualitatively verified by experimental observation using SprayWatch© imaging diagnostics equipment. Images captured by the equipment confirm that the particles travel through the plasma plume with high momentum and show no sudden change in theirtrajectories right before impacting the substrate. Both the numerical and experimental findings show that the freestream model is sufficiently detailed for future work of this nature.

Jet in Supersonic Crossflow on a Flat Plate

Abstract: A three dimensional full Navier-Stokes CFD model with the Smith κ κ κ κ-κl turbulence model is used to compute the interaction between a transverse jet and a supersonic crossflow. A new flow model for jets in supersonic crossflow is presented. Details of shock structure, vortex origination and separation/reattachment zones are described. Amplification coefficients are defined and calculated to quantify the obstruction component of the jet interaction forces and moments. The amplification coefficients increase nearly linear with freestream Mach number.

On the interaction between the shock wave attached to a wedge and freestream disturbances

Abstract: We present a study of the interaction of small amplitude, unsteady, freestream disturbances with a shock wave induced by a wedge in supersonic flow. These disturbances may be acoustic waves, vorticity waves, or entropy waves (or indeed a combination of all three). Their interactions then generate behind the shock disturbances of all three classes, an aspect that is investigated in some detail. Also, the possibility of enhanced mixing owing to additional vorticity produced by the shock-body coupling is investigated. It is shown that disturbances behind the shock may either decay downstream, or alternatively experience sustained oscillations. The precise regimes under which either behaviour is found are stated.

Application of Godunov's Method to Blunt-Body Calculations

Abstract: A modification of Godunov's finite-difference method for computation of steady or unsteady flowfields about planar or axisymmetric blunt bodies is presented. Results for ideal gas flows over two body shapes are shown. The first case is that of a sphere in a Mach number 10.0 freestream, and is used to evaluate the accuracy of predicted results by comparison with other computations. Pressures and stagnation point velocity gradient are found to be accurate to within several percent and are improved in the stagnation region over the values previously achieved with the method. The second test shape is that of a spherically blunted cone both with sharp and rounded shoulders. Two freestream conditions were employed, one resulting in an essentially subsonic shock layer and the other in an essentially supersonic shock layer. Body pressures and shock shapes are presented and compared with available data.