On Recirculation Region Length of Suddenly Expanded Supersonic Flows, Using CFD and Fuzzy Logic

This paper aims to introduce the core features of the Fuzzy Logic (FL) approach in simulations of turbulent Supersonic flows as a cost-effective methodology. Computational Fluid Dynamic (CFD) analysis is conducted to study the effect of Mach number (Me), nozzle pressure ratio (NPR) and expansion corners (EC) on primary recirculation region length (Xr1). An Open FOAM numerical solver was used for this purpose. The CFD results developed were focused on developing relationships between input and output using the Mamdani-based fuzzy logic approach. This approach used membership functions viz. Triangular, Generalized bell shape and Gaussian membership functions. The models developed were matched with confirmatory test cases which differ from the training data. The flow field contours showed that the flow field generated numerous intrinsic features in the corner vortex. Also, the Triangular membership function made better predictions than the other two functions as it had a least absolute percentage error of 9.0705%.