High Circumferential Velocity Research Articles

Numerical Investigation of Enhanced Dilution Zone Mixing in a Reverse Flow Gas Turbine Combustor

An advanced method for dilution zone mixing in a reverse flow gas turbine combustor was numerically investigated. For long mixing lengths associated with reverse flow combustors (X/H > 2.0), pattern factor was found to be mainly driven by nozzle-to-nozzle fuel flow and/or circumferential airflow variations; conventional radially injected dilution jets could not effectively mix out circumferential nonuniformities. To enhance circumferential mixing, dilution jets were angled to produce 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, thus enhancing turbulent shear at the expense of jet penetration. Three-dimensional CFD calculations were performed on a three-nozzle (90 deg) sector, with different fuel flow from each nozzle (90, 100, and 110 percent of design fuel flow). The computations showed that the optimum configuration of angled jets reduced the pattern factor by 60 percent compared to an existing conventional dilution hole configuration. The radial average temperature profile was adequately controlled by the inner-to-outer liner dilution flow split.

Application of Dynamic Modeling Technique to the Analysis and Prediction of Heat Transfer with Particular Reference to Agitated Vessels

A common operation in the process industries is that of a rate process controlled by a series of resistances. Typical are batch heat transfer operations and diffusional processes such as gas-catalyst reactions. During the operation of a plant, steady-state measurements of performance are frequently not obtainable and individual resistances must be extracted from overall measurements made under non-steady-state conditions. The basis of a mathematical model and its application to establishing the batch- and service-side heat transfer coefficients and overall fouling factor for an agitated vessel are described. Specifically, the paper is concerned with the calculation of jacket coefficients where high circumferential velocities are induced by feeding coolant into the jacket annulus through tangential nozzles. A Nusselt-type expression for this geometry is presented.