Leveraging ATS Technology
The following discusses the ATS technology introduced during commissioning of the 420-MWe W501G and currently being incor-porated in other SWPC gas turbine systems. The combustion outlet temperature in these tests was within 50 oF of the projected ATS temperature.
Closed-Loop Steam Cooling
The W501G unit applied closed-loop steam cooling to the combus-tor “transitions,” which duct hot combustion gas to the turbine inlet. Four external connections route steam to each transition supply manifold through internal piping. The supply manifold feeds steam to an internal wall cooling circuit. After the steam passes through the cooling circuit, it is collected in an exhaust manifold and then is ducted out of the engine.
Testing at Lakeland proved the viability of closed-loop steam cool-ing, and confirmed the ability to switch between steam and air cool-ing. The steam cooling clearly demonstrated superiority over air cooling.
Optimizing Aerodynamics
In parallel with W501G testing, SWPC validated the benefits of ap-plying the latest three-dimensional design philosophy to the ATS four-stage turbine design. This was con-ducted in a one-third scale turbine test rig, incorporating the first two stages. SWPC conducted the test-ing in a shock tube facility at Ohio State University, which was instru-mented with over 400 pressure, tem-perature, and heat flux gauges. An aerodynamic efficiency increase at-tributed to the use of “indexing” sur-passed expected values.
High-Temperature TBCs
TBCs are an integral part of the W501ATS engine design. An on-going development program evalu-ated several promising bond coats and ceramic materials prior to the W501G tests. The selected ad-vanced bond coat/TBC system un-derwent 24,000 hours of cyclic accelerated oxidation testing at 1,850 oF. The W501G incorporated the selected TBC on the first and second row turbine blades. Plans are to incorporate the TBC system into other SWPC engines.
Compressor
The W501G incorporates the first 16 stages of the 19 stage ATS compressor, designed to deliver 1,200 lb/sec airflow with a 27:1 pressure ratio. SWPC slightly modified the last three stages for the W501G compressor and changed vanes 1 and 2 from modulated to fixed. This resulted in air delivery at the ATS mass-flow rate of 1,200 lb/sec, but at a pressure ratio of 19:1, which optimizes the compressor for the W501G system.
The roots of the compressor design are in three-dimensional vis-cous flow analyses and custom de-signed, controlled-diffusion airfoil shapes. Controlled-diffusion airfoil design technology evolved from the aircraft industry. The airfoils emerg-ing from these analytical methods are thinner and shaped at the ends to reduce boundary layer effects. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：Advanced Turbine Systems 先进的涡轮系统(7)
