The combustion chamber represents the core of any gas turbine. Here, energy stored inside the fuel is released under high pressure and temperature. The high thermal load on the components as well as numerous strict requirements in terms of safety and reliability make the combustor the most sophisticated components of the gas turbine. Increasing demands in terms of NOx and CO emissions for environmental protection nowadays additionally necessitate leaning out the flame and operating the burner close to its blow out limit. Modern simulation tools help to achieve the goals and bring the technology to its edge, but experimental investigations are still a central part of the combustor development process.
Within the last three years, Kawasaki Heavy Industries Ltd. and B&B-AGEMA have worked on a technology to support experimental tests for development of the Micromix technology for combustion of pure hydrogen, allowing a very close visual access to the burner. The invented borescope has been designed with support of conjugate heat transfer simulations conducted in Star-CCM+ as well as FEM calculations conducted with Siemens NX Nastran. Different design variations have been tested, internal cooling pathways improved and the structure enhanced to substantially increase the life time of the borescope head located directly downstream of the flame. Here, the local temperature reaches approx. 1600 K.
The borescope could have been successfully operated in one low pressure and one high pressure test. The acquired information helps to understand the behavior of the combustor, to improve the design and plan the operation strategy within the real gas turbine.
Presenter: Andreas Hogenschurz, Project Engineer