A. Dumitrache

128 Nonlinearity, Bifurcation and Chaos – Theory and Applications

onset of flow bifurcations [40, 41].

**6. Conclusion** 

neglected \* *y* 1 .

distribution of shear stress.

empirical constant was need.

examined.

The nonlinear flow equations, the initial solution used for the numeric computations and the length of the airfoil midpart with a small or zero curvature are the principal factors for the

In the beginning of the chapter we have achieved an analytic solution that approximates a two-dimensional Coanda flow. The validity of the results is limited to the cases given by *b R*/ 1, since in the tangential component of momentum equation the curvature was

The validity of the laminar solution is for Reynolds numbers smaller than the critical value which is of the order <sup>4</sup> 3 10 . For the turbulent flow the similarity assumption has been reduced primarily to the general development along the flow, leaving the transverse

In this model the edge of the intermittent flow has been neglected, so that assuming constant turbulent viscosity in cross section has lead to similar velocity profiles for both the laminar and turbulent flow. However, the general configuration of the flow development was different. In order to specify the development of this self-modeled flow only one

In many applications that use boundary layer control by tangential blowing, the solid surface downstream of blowing slot is strongly curved and, in this case, the prediction of jet involves separation and a more accurate knowledge of the flow (radial and tangential

The compressible Reynolds-averaged Navier–Stokes (RANS) equations have been solved for circulation control (CC) airfoil flows. Different turbulence models have been considered for closure, including the Spalart–Allmaras model with and without a curvature correction and the shear stress transport (SST) model of Menter. Numerical solutions have been computed with a structured grid solver. The effect of mesh density on the solutions has been

We have investigated the characteristics of various Coanda surfaces, involving smooth curved surfaces and a polygonal curved surface with flap. Using the FLUENT code we have

Further, we have taken interest in the detailed behavior of an existing Coanda ejector model, used in propulsion systems. For numerical investigations we have used an implicit formulation of RANS equations for axisymmetric flow with a shear stress transport *k*

(SST model) turbulence model. The numerical results have been obtained for a total pressure range of 1-5 bars, imposed at the reservoir inlet. The goal was to investigate the influence of various geometric parameters and pressure ratios on the Coanda ejector performance. The effect of various factors, such as the pressure ratio, primary nozzle and ejector configurations on the system performance has been evaluated based on the

analyzed the distribution pressure and separation on the considered surfaces.

pressure - velocity profiles) which has been done by CFD methods.

*Institute of Statistics and Applied Mathematics of the Romanian Academy, Bucharest, Romania* 
