Analysis of geometric and non-geometric parameters in a Coanda device for marine applications

Abstract

This numerical study comprises the geometric evaluation of turbulent, steady-state, two-dimensional, and incompressible flows over the Coanda effect-based H.O.M.E.R. (High-Speed Orienting Momentum with Enhanced Reversibility) nozzle. The main purpose is to evaluate the influence of the central septum insertion (P) and change in dimensionless mass flow rate between two inlets (m*) over the deflection angle of the mixed jet (α), velocity fields (V), and thrust forces per unit length (F) at the nozzle exit. The time-averaged conservation equations of mass and momentum have been solved using the Finite Volume Method for all simulations. Turbulence closure is solved using RANS (Reynolds-Averaged Navier–Stokes) and standard k-ε modeling. Results show the septum insertion associated with the mass flow rate difference as possible important parameters for controlling the exit jets and forces generated in the device. Moreover, higher magnitudes of m* associated with a high intruded septum (P = 11 mm) in the device led to the highest magnitudes of forces in the y-direction, while intermediate configurations of m* and P are best for maximizing forces in the x-direction. For the present conditions, the forces generated in the y-direction are almost four times higher than that generated in the x-direction, indicating that this device can be suitable for maneuverability purposes.