DOI: 10.1615/ICHMT.1994.IntSympHetatTransTurb
ISBN Print: 1-56700-016-9
ISBN Print: 978-1-56700-016-0
Advanced Gas Turbine Combustor Cooling Configurations
摘要
Basically, a gas turbine combustor is designed to convert air from the compressor into hot gas, which is ducted to the turbine. Local deviations from mean temperature of this hot gas should be as small as possible to prevent localized overheating at the turbine. Currently, mean hot gas temperatures run in the vicinity of 1900 K max. Ideally, the combustor wall would therefore attain a temperature of 1900 K max, if the need for combustor cooling could be eliminated altogether. Materials able to safely sustain temperatures of such levels are not available. It is therefore necessary to cool the combustor walls down to temperatures that can be sustained by available materials. This cooling effort is governed by the following constraints:
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- hot gas temperature
- cooling air temperature
- allowable materi-al temperature
- cooling air flow
- service life
- surface to volume ratio.
On the other hand, the temperatures and temperature gradients of the combustor wall must be adjusted such that the life target can be achieved. Ultimately, a cooling configuration is sought that provides especially effective cooling. This is why various characteristics have been adopted as criteria in the assessment of cooling configurations. These are film-cooling effectiveness, cooling air utilization and total cooling effectiveness.