WALL-MODELED LARGE EDDY SIMULATION AND CONJUGATE HEAT TRANSFER FOR COMBUSTOR AEROTHERMAL APPLICATIONS

In modern day gas turbine hot sections, active cooling of liner walls is critical due to extremely high temperatures and long continuous operation. Reduced thermal stress increases the life cycle of engines' components while meeting the ever-greater demands for cycle efficiency and low operational costs. A secondary flow network can be introduced to shield the metal surfaces by forming a film, increasing the durability and life of the liner. The interactions of the effusion cooling with the cross flow and properly capturing wall effects are critical for accurate heat transfer predictions. High fidelity simulations are used to improve the overall performance and durability of gas turbine engines. The simulations recover the distribution of temperature in both solid and fluid zones, thereby allowing design engineers to develop designs for next generations of gas turbines, along with prognosis of existing engine designs. However, the high level of fidelity is accompanied by computational cost, along with complex numerical modeling approaches, especially for numerical models utilized for the life cycle assessment of gas turbine engines. This paper uses a numerical study using Ansys Fluent to evaluate Wall-Modeled Large Eddy Simulation (WMLES), along with WALE as sub grid scale model, Conjugate Heat Transfer (CHT), and radiation to explore its benefits for practical use in industrial combustion applications. The predictions from various LES methods vary significantly near the wall, where the solution depends on much finer grid resolution. Various methods for modeling WMLES are compared both in the context of computational accuracy and cost. The simulations are performed using open literature experiments such as heated nozzle exhaust over an effusion cooled plate [1], and air/air effusion/slot cooling combustor liner experiment [2]. The accuracy of the simulation approach is assessed by comparing solid plate temperature data from the experiments. In this study the effects of WMLES-CHT are explored with a focus on thermal coupling, radiation, etc. The comparisons in the paper allow the selection of best practices to accurately model CHT for practical use in gas turbine applications. In general, numerical investigation matches experiments quite well, both qualitatively and quantitatively.