Heat Release Analysis of The Scaled and Colliding Sprays Using RANS Approach

Abstract

This study tries to optimize the heat release rate of a diesel injector that is injecting into a constant volume combustion chamber. This optimization is performed via spray scaling through Reynolds Averaged Navier-stokes simulations (RANS). The spray-A (diesel spray from Engine Combustion Network) has been used as a reference for validation of the simulations. To scale the diesel jet, the injected mass and cross-sectional area of the injector are varied with similar scaling factor. It was found that using a larger injector leads to a longer spray penetration, ignition delay, and burn duration while it helps a more complete combustion. On the other hand, using a smaller orifice improves the burn duration and reduces the heat release, while it causes a slightly higher amounts of unburned hydrocarbons. It was revealed that it is reasonable to use multiple smaller orifices (two half size or four quarter size injectors) in place of one single injector, to improve the burn rate. To achieve a complete combustion, the configuration must be tuned. For clarity, three configurations are considered, parallel, non-coaxial colliding and co-axial colliding sprays for which the distance between the sprays and the inclination of the sprays are varied and tested. The advantages and disadvantages of each configuration is discussed in length.