Comparison of Different Combustion Liner Cooling Techniques Under Non-Reacting Conditions For A Lean Pre-Mixed Fuel Nozzle

摘要

While the gas turbine research community is continuously pursuing higher cyclic efficiency designs by increasing the combustor firing temperatures and thermally resistant turbine vane/blade materials, a simultaneous effort to reduce the emission levels of high temperature driven thermal NOX also needs to be carried out. Lean premixed combustion has been found as one of the solutions to these objectives. However, since less amount of air is available for backside cooling of liner walls, it becomes very important to develop an optimum cooling configuration for these liners. In the present study, the performance of cooling techniques for a combustion liner of an in-house combustor geometry was compared using commercial computational fluid dynamics tool. The cooling configurations investigated were forced convection, jet impingement, effusion cooling and a combination of jet impingement and effusion cooling. Conjugate simulations were carried out to effectively model the solid combustor liner and its interaction with the main and coolant fluid. The results were represented in terms of non-dimensional overall cooling effectiveness. The combination of effusion and impingement cooling had the highest overall cooling effectiveness, followed by the effusion cooling configuration and then the impingement cooling configuration. In addition, the overall cooling effectiveness was also plotted against the pumping power which showed that the effusion-impingement combination had the highest cooling effectiveness for the least pumping power penalty.