NUMERICAL ANALYSIS OF DILUTION HOLES DETERIORATION IMPACTING THE PERFORMANCE OF A V2500 COMBUSTOR

摘要

In aero engine combustors, dilution air jets are used to additionally tailor the temperature field, the emissions, and the turbine inlet profile. These jets are entering the combustion chamber at different axial and circumferential locations through dedicated holes in the combustor liners. By deterioration, the diameters of these holes can significantly change over operation time. To evaluate the impact of such deterioration in the MRO context, the authors created a numerical model of a V2500 aero engine combustor and analyzed the impact. The data of dilution holes deterioration is based on the nominal design according the engine manual and the deviation measured for three engine combustors during maintenance inspection.The processes inside an aero engine combustor are very complex. To achieve most reliable information, a multi-physics approach was chosen for this evaluation. Validated in the past with a wide range of different academic test cases as well as industrial combustor test rigs, the evaluation allows conclusive analyses of the described deterioration. Back-to-back comparisons of individual variations reveals the most significant dilution holes row and give information about potential local shifts in combustor liner heat loads as well as in the exit profiles. Especially the distortion of the film cooling by the local interaction with the dilution jets could be observed.Since the deterioration of the dilution holes measured for the three combustors inspected is very small compared to the nominal design, the authors payed a lot of attention also on analyzing the model sensitivity. Increasing the spatial resolution, the plausibility of the numerical results were checked by analyzing the flow splits and the dilution jets penetration. The final step was the variation of the dilution holes individually and combined and the evaluation of resulting temperature distribution at the combustor liners and changes in the exit profile.Due to the fact that a multi-physics solver developed in the framework of OpenFOAM could be used, the authors could do these quite intensive CFD studies highly parallelized and, thus, in an acceptable time. The scalability of the solver reported already in former publications could be shown also in this application to the real engine combustor with a high level of complexity