Coanda Wall Jet Calculations Using One- and Two-Equation Turbulence Models

Abstract

The wall jet over a convex surface, the Coanda wall jet, has many potential technical applications, such as circulation control of airfoils. Reynolds-averaged Navier-Stokes is a potentially very powerful tool for Coanda wall jet calculations. A number of common linear eddy-viscosity turbulence models were used for Reynolds-averaged Navier-Stokes calculations of a turbulent Coanda wall jet experiment. Calculations were also carried out with an explicit algebraic stress model. The differences in the computed results were shown to be large depending on what turbulence model was employed. The k-w model was then employed for three-dimensional Reynolds-averaged Navier-Stokes calculations where the downstream evolution of streamwise vortices in the turbulent wall jet was studied for various spanwise wavelengths and forcing amplitudes. It was found that a centrifugal instability of the turbulent mean flow may lead to the streamwise growth of longitudinal vortices. Beyond a certain disturbance amplitude threshold the relative phase of the vortices had a noticeable impact on the amplification rates and the mean flow characteristics were affected by the added wall normal momentum exchange.