A practical computational fluid dynamics (CFD) approach to modeling effusion orifices in gas turbine combustor liners is proposed specifically when liner metal geometry is not included and conjugate heat transfer is not invoked. The focus is on eliminating effusion orifices from the model while maintaining the imprint of the orifices on the cold and hot sides of the liner wall. The imprinted boundaries serve as embedded mass flow inlets and outlets on both sides of the wall and maintain the integrity of the wall geometry. An empirical model is then used to extract and inject mass from the cold and hot sides of the liner, respectively. The mass extraction and injection process is performed for each orifice based on local conditions such as pressure, temperature and discharge coefficient. The discharge coefficient is, in turn, dynamically computed for each orifice based on approach angle, approach Mach number, discharge Mach number and orifice length to diameter ratio. With this approach, the fidelity of the liner wall is preserved for better heat transfer predictions and easier near wall meshing. In addition, the discharge coefficient is not assumed but calculated allowing the redeployment of inherently inadequate effusion orifice mesh cells to other critical areas of the combustor. Presented are results of two combustor cases to demonstrate the practicality and accuracy of the proposed method as compared to standard effusion modeling and their comparison with rig data.
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