Effect of Geometric Parameters on Simplex Atomizer Performance

A computational analysis of flow in simplex fuel atomizers using the arbitrary-Lagrangian–Eulerian method is presented. It is well established that the geometry of an atomizer plays an important role in governing its performance. We have investigated the effect on atomizer performance of four geometric parameters, namely, inlet slot angle, spin chamber convergence angle, trumpet angle, and trumpet length. For a constant mass flow rate through the atomizer, the atomizer performance is monitored in terms of dimensionless film thickness, spray cone half-angle, and discharge coefficient. Results indicate that increase in inlet slot angle results in lower film thickness and discharge coefficient and higher spray cone angle. The spin chamber converge angle has an opposite effect on performance parameters, with film thickness and discharge coefficient increasing and the spray cone angle decreasing with increasing convergence angle. For a fixed trumpet length, the trumpet angle has very little influence on discharge coefficient. However, the film thickness decreases, and spray cone angle increases with increasing trumpet angle. For a fixed trumpet angle, the discharge coefficient is insensitive to trumpet length. Both the spray cone angle and the film thickness are found to decrease with trumpet length. Analytical solutions are developed to determine the atomizer performance considering inviscid flow through the atomizer. The qualitative trends in the variation of film thickness at the atomizer exit, spray cone angle, and discharge coefficient predicted by inviscid flow analysis are seen to agree well with computational results.