CFD analysis of turbulent twin-impinging round jets was performed to establish the growth profile and velocity characteristics of resultant jet. To ensure that a high degree of confidence can be assigned to the planned multi-jet impingement simulations, a single axisymmetric jet was first numerically resolved and compared to published jet experiments results. This required the definition of inlet boundary condition of the jet to be accurately documented. To that end, a turbulent flow exiting a long circular pipe was first modelled and analyzed to ensure that the inlet boundary condition to a single axisymmetric jet was in good agreement with the experiments.
Once, the development length based on mean velocity was calculated, the pipe flow at a Reynolds number of 7,500 was analyzed and compared with in house and published experimental data. It was observed that the solution using the SST turbulence model performs better than the solution obtained using the Realizable k-e model in the pipe domain. Once the analysis was completed, velocity and turbulence components at the outlet of the pipe were extracted and used as input for the single jet flow simulations.
Single axi-symmetric round jet flow was analyzed using computational techniques and validated with experimental results to establish the suitable turbulence model for simulation of low Reynolds number jets exiting from fully developed pipe. It was observed that although all the turbulence models studied could closely predict the mean velocity field, they were not able to accurately predict the turbulence intensity distributions. From the models studied, it was concluded that SST k-? model was the best turbulence model for simulating low Reynolds number jet flow exiting from fully developed pipe.
Based on the insight gained from single jet analysis, CFD analysis on turbulent impinging jets was performed. Multiple Reynolds numbers and impingement angles were considered for the study to gain better understanding of the parameters affecting resultant jet growth and distribution. Based on the mesh obtained from grid sensitivity study, jets impinging at 30o, 45o and 60o at constant Reynolds number of 7500, and jets impinging at 30o angle at Reynolds number of 5000, 7500 and 10000 were numerically analyzed. It was observed that the profile of the resultant jet closely matched with the prediction of elliptical profile predicted by past researchers. It was also seen that higher jet growth was predicted in case of jets impinging at higher angle and higher momentum of jets were predicted in case of jets impinging with higher Reynolds number. Hence, it was concluded that based on the application required; ideal impinging strategy can be applied for obtaining optimal results.