Evaluation of the Performance of Various Turbulence Models for Accurate Numerical Simulation of a 2D Slot Nozzle Ejector
Date of Award
Master of Science (MS)
With the development over the last several decades, accurate Computational Fluid Dynamics (CFD) modeling has now become an essential part in the analysis and design of various industrial products where the fluid flow plays an important role. The goal of this thesis is to apply the CFD technology to the analysis of a 2D slot nozzle ejector which has application in Short Take-off and Landing (STOL) aircraft and other future aerospace vehicles. In the nozzle-ejector configuration, the high speed air flow from the nozzle entrains the ambient air into a mixing chamber (ejector) as a means to create additional thrust for a STOL aircraft. In 1973, the effectiveness of a slot nozzle ejector configuration in generating additional thrust was evaluated experimentally by Gilbert and Hill of Dynatech under a NASA contract . In this research, numerical simulations of this experimental configuration are performed and compared with the experimental data. An accurate computational model for simulations requires solving the appropriate governing equations of fluid dynamics using an accurate numerical algorithm on an appropriately clustered mesh in the computational domain . We employ the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations to model the turbulent supersonic flow in the 2D slot nozzle ejector. These equations require the computation of turbulent stresses which are modeled by using a turbulence model. The choice of a turbulence model can affect the accuracy of the solution because of their empirical nature. The goal of this research is to evaluate five turbulence models and determine the best possible model that can most accurately simulate the ejector nozzle mixing flow. The five turbulence models employed are the one-equation Spalart-Allmaras (SA) model, two-equation standard k-ε and SST k-ω models, the four-equation Transition SST model, and the SAS-SST k-ω model. The effectiveness of each turbulence model is determined by comparing the computational results with the experimental data. For the computations, an unstructured mesh is generated using the ICEM CFD 14.5 software and the flow field is calculated using the commercial CFD solver ANSYS-Fluent.
Dr Ramesh K Agarwal
Permanent URL: https://doi.org/10.7936/K74M92HN