| Popis: |
Modern gas turbines work under demanding high temperatures, high pressures, and high rotational speeds. In order to ensure durable and reliable operation, effective cooling measures must be applied to the high-temperature rotating components, including turbine blades and turbine disks. Cooling technology, however, is one of the most challenging problems in this field. The present work reviews the current state of cooling technology research, at both the fundamental science and engineering implementation levels, including modeling and simulation, experiments and diagnostics, and cooling technologies for blades and disks. In numerical simulation, the RANS approach remains the most commonly used technique for flow-dynamics and heat-transfer simulations. Much attention has been given to the development of improved turbulence modeling for flows under rotation. For measurement and diagnostics, advanced instrumentation and rotating-flow test facilities have been developed and valuable experimental data obtained. Detailed velocity and temperature distributions in rotating boundary layers have been obtained at scales sufficient to resolve various underlying mechanisms. Both isothermal and non-isothermal conditions have been considered, and the effects of Coriolis and buoyancy forces on flow evolution and heat transfer quantitatively identified. Cooling technologies have been improved by optimizing cooling passage dsigns, especially for curved configurations under rotation. Novel methods such as lamellar cooling and micro-scale cooling were proposed, and their effectiveness evaluated. For disk/cavity cooling, efforts were mainly focused on rotor-stator systems, with special attention given to the position of air injection into disks. |
