Design of Spike Nozzle and Comparison of Turbulence Models in Numerical Simulation of its Flow-field in Design and Off-design Conditions

This study is a try to design a spike nozzle and simulate its flow-field in different conditions. Hence, spike nozzle design methods were studied and accordingly the design code was developed. Then the behavior of flow in this type of nozzle was simulated numerically by means of computational fluid dynamics. In order to conduct the simulations, four turbulence models suitable for solving the flow-field of spike nozzle were used, not only to model the performance of the nozzle in design and off-design conditions, but also to identify the best model for the accuracy of the solutions. To ensure the accuracy of the simulations, numerical results and experimental data were compared. It was found that applied models in case of using high quality grids with proper dimension near the nozzle walls, can predict the nozzle flow pattern with acceptable approximation. Also the comparisons revealed that the amount of pressure on the spike wall calculated by Realizable k-ε model, is generally identical with experimental results and in the worst condition the difference between them is 15%, so this model has the best agreement with experimental results. Besides, comparison of taken photos during experiments and extracted contours from numerical analysis, shows the high ability of applied numerical method to predict spike nozzle flow-field. Therefor it can be claimed that by using the proposed method in this research, there is no need to perform cold-flow tests during the design and construction of spike nozzles.