Clocking between the jet engine combustor fuel nozzle and the first vane in the turbine mitigates the hot streak from the combustor.  The exit gas from the first vane with lowered and more uniform temperature reduces the required cooling air from the downstream rows, which in turn improves the overall efficiency of the engine.  Clocking is more beneficial when the hot streak, or the non-uniformity of the exit temperature from the combustor, is strong.  The non-uniformity of the temperature profiles is usually quantified by pattern factor.  In the current study, a modern combustor design, coupled with high pressure turbine, is used to study the difference in the temperature profile at the exit of the first vane and heat flux on blade surface of the second row of the turbine, from different positioning between the combustor and turbine.  High-fidelity eddy-resolving simulation was used in the combustor and turbine flows.  With more turbulence resolved in the hybrid RANS/LES approach, it provides more realistic turbulent fluctuations at the turbine inlet, and better mixing in the secondary flow in the high pressure turbines.

Combustor exit temperature profiles both from the combustor CFD and from the measurement are used in the turbine at inlet.  Moreover, modulated temperature profiles with more pronounced pattern factor are also used.  A threshold of the pattern factor that brings the benefit of clocking is thus identified.  Clocking positioning between the combustor and vanes was studied for most benefit.  Modern engines with high rotating speed and thus high flow turning in the first vane requires different design strategy of coupling as in the legacy designs.  The high-fidelity simulation enables careful calibration of the positioning of the combustor and vanes.  Comparative results from different design configurations will be shown in the final paper


Hybrid RANS/LES Simulation of Combustor/Turbine Interactions

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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