An advanced method for dilution zone mixing in reverse flow gas turbine combustors was experimentally investigated. To enhance circumferential mixing, dilution jets were injected with a high circumferential (swirl) velocity component. The jets on the outer liner were angled in one direction while the jets on the inner liner were angled in the opposite direction. To demonstrate reduced pattern factor, AlliedSignal Engines' F109 combustor WU tested at sea level takeoff conditions. For the

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... (conventional) configuration, the experimental results showed that large scale circumferential temperature nonuniformities at the turbine inlet were caused primarily by fuel flow variations from nozzle to nozzle. These temperature variations were significantly reduced by angled dilution jets. A pattern factor of 0.102 was achieved compared to the best case pattern factor of 0.163 for the baseline configuration. The only combustor modification was the dilution hole configuration. The radial average temperature profile produced by angled dilution jets was very similar to the profile produced by the baseline configuration. 12 Smplex-Pilomd Aitblast Fuel Nozzles FIGURE 1. ALLIEDSIGNAL 1909 REVERSE FLOW ANNULAR COMBUSTOR Current and advanced combustors inject dilution air into the dilution zone through a pattern of holes in the combustor liner. The dilution jets should effectively mix with the combustion gases, thereby establishing an appropriate average radial temperature profile and an acceptable maximum spatial temperature. The design radial temperature profile, with maximum temperature typically occurring at the 50% to 70% radial position, is usually obtained rather easily. On the other hand, the maximum spatial temperature is difficult to control in most cases. Reducing the maximum spatial temperature (for a given average combustor exit temperature) can result in significant improvement of turbine inlet guide vane life and/or engine efficiency. The maximum spatial temperature is