Cold Flow Diluent Mixing Study Using Radial High Density Ratio Jets Into a Circular Freestream

Project Themis is a recently created Air Force Research Laboratory (AFRL) research program that seeks to bridge the gap from lab-scale to full-scale testing and aid in developing engine technologies to a technology readiness level (TRL) of 4, so that they may be transitioned to current or future engine programs. The goal is to research technologies associated with combustion devices using hydrocarbon fuel that support increased engine life, performance, and thrust-to-weight ratio. Preliminary literature search results show three areas that need further investigation. These are 1) the effect of injector type and chamber geometry on the main chamber performance and heat transfer, 2) the use of transpiration cooling for main chamber life, and 3) improvements on preburner temperature uniformity at the exit. Project Themis seeks to increase the understanding of impact of design variations in the diluent mixing at supercritical conditions especially in a 3D environment. The configuration of interest is jets injected transversely into a crossflow in a circular duct. Themis plans an experiment to study supercritical mixing in addition to the computational modeling efforts. The objective of the Advatech support effort is to use computational results to provide insight into the behavior of supercritical jets injected transversely into a crossflow in a circular duct. Computational Fluid Dynamics (CFD) models of the experiment using Reynolds-averaged Navier-Stokes are employed to provide insight into the interaction between the injected and freestream fluids, as well as between the jets themselves. CFD simulations are also used to perform numerical experiments with variations of momentum flux ratios in support of design of the cold flow test apparatus. An experiment is planned to study supercritical mixing in addition to the computational modeling efforts. The radial port geometry and arrangement are the principal design change that can be implemented to meet the temperature-mixing goals. The cold flow work will compare various configurations and their abilities to properly mix the diluent with the main flow stream. Configuration will begin with a single jet to validate the test results with the modeling tools and then moving to various port shapes and numbers.