Numerical simulation study of the injection characteristics affecting trans-/supercritical sprays based on orthogonal experiment design

A mixture of numerical models and orthogonal experiments was used to better understand the mixing behavior and heat/mass transfer in jets operating under supercritical conditions. The goal is to investigate the effects of injector diameter (Dinj), ambient pressure (Pamb), injection temperature (Tinj), injection velocity (Vinj), and ambient temperature (Tamb) on jet evolution. The findings highlight that, among these parameters, Tinj and Dinj exert the most substantial impact on jet mixing characteristics. Higher Tinj and Dinj enhance the jet spreading angle (θhsa) and mixing layer thickness (δ) for improved mixing efficiency. Increasing Tinj and reducing Dinj effectively shorten the potential core length (Lp). Moreover, higher Tinj enhances the temperature rise rate (Tr), effectively raising fuel temperature over a shorter distance. The velocity decay rate (Vd) increases with Vinj and Tinj. Furthermore, this study explores the effects of injection density ratio on evaluation indexes (θhsa, Lp, Vd, Tr and δ) for jet mixing efficiency and trends of jet structural development (Lp, turbulent chaos length (CL) and self-similarity length (SL)). These findings are important for understanding supercritical spray development, guiding engine chamber design and setting operational conditions based on spray behavior.