An experimental investigation of a nonreacting multiple jet mixing with a confined crossflow has been conducted. Flow and geometric conditions were varied in order to examine favorable parameters for mixing. The requirement for a rapid and intense mixing process originates from combustion applications, especially the RQL-combustion concept. Thus, the jets were perpendicularly injected out of one opposed row of circular orifices into a heated crossflow in a rectangular duct. Spacing and hole size were varied within the ranges referring to combustor applications. The results presented are restricted to an in-line orientation of opposed jet axis. Temperature distribution, mixing rate, and standard deviation were determined at discrete downstream locations. Best, i.e., uniform mixing can be observed strongly depending on momentum flux ratio. For all geometries investigated, an optimum momentum flux ratio yields to a homogeneous temperature distribution in the flow field downstream of the injection plane. Overly high ratios deteriorate the mixing process due to the mutual impact of the opposed entraining jets along with a thermal stratification of the flowfield. Correlations are introduced describing the dependency of optimum momentum flux ratio on mixing hole geometry. They allow the optimization of jet-in-crossflow mixing processes in respect to uniform mixing.
An experimental investigation of a non-reacting multiple jet mixing with a confined crossflow has been conducted. Flow and geometric conditions were varied in order to examine favourable parameters for mixing. The requirement for a rapid and intense mixing process originates from combustion applications, especially the RQL-combustion concept. Thus, the jets were perpendicularly injected out of one opposed row of circular orifices into a heated crossflow in a rectangular duct. Spacing and hole size were varied within the ranges referring to combustor applications. The results presented are restricted to an inline orientation of opposed jet axis. Temperature distribution, mixing rate and standard deviation were determined at discrete downstream locations. Best i.e. uniform mixing can be observed strongly depending on momentum flux ratio. For all geometries investigated an optimum momentum flux ratio yields to a homogeneous temperature distribution in the flowfield downstream of the injection plane. Too high ratios deteriorate the mixing process due to the mutual impact of the opposed entraining jets along with a thermal stratification of the flowfield. Correlations are introduced describing the dependency of optimum momentum flux ratio on mixing hole geometry. They allow the optimization of jet-in-crossflow mixing processes in respect to uniform mixing.
The injection of jets normal to a crossflow is a key technology for the development of an advanced low NO gas turbine • based on a Rich-Burn/Quick-Quench/Lean-Burn (RQL) combustor. The RQL combustor depends on an efficient quick mix section that rapidly and uniformly dilutes the rich zone products to minimize emissions. Therefore, an experimental investigation of a non-reacting mixing process of jets in a crossflow was conducted. The jets were perpendicularly injected through one stage of opposed rows of circular orifices into a slightly heated crossflow within a rectangular duct. AU geometries were tested with staggered arrangements of the centerlines of the opposed jets. The temperature distribution was measured and from that the mixing rate was determined for parametric variations of flow and geometric conditions. In accordance with the application to RQL-combustion, emphasis was put on high momentum flux ratios with high massflow addition. The experimental study provides the data base for a correlation of best mixing depending on geometric conditions for staggered mixing configurations. The correlation presented specifies the optimum momentum flux ratio as a function of the duct height to hole diameter ratio and the relative spacing of the injected jets.
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