Thermal Response Turbine Shroud Study.
Abstract
The program objective was to evaluate active clearance controls (ACC) for future military fighter and transport aircraft/engines, rank the candidate schemes, and recommend a future course of action. Fifty-one potential ACC concepts were reduced to twelve: five mechanical, two pneumatic, and five thermal. The fighter and transport missions selected were the Advanced Tactical Fighter (ATF), and the C141X strategic aircraft. Three levels of controls for ACC were considered: simple on/off two-position; open loop infinitely variable; and feedback (requiring a clearance sensor). On/off systems were selected for study because the majority of the benefit is obtained during cruise/dash and the open and feedback systems have positioning and reliability uncertainties. The criteria selected to evaluate the different schemes were net Life Cycle Cost benefits, to the fleet over the life of the weapons system. These criteria were based on a new-engine/new-aircraft application where efficiency improvements due to ACC were used to reduce aircraft and engine size for a fixed mission (range, payload, etc.). The detailed operation and impact (cost, weight, reliability, maintainability) of the twelve final schemes were evaluated by adopting each of the candidate schemes to selected stages in the base engines. ACC showed a significant net benefit in the transport high pressure turbine. On the low pressure turbine some schemes showed a net savings, but the amount was small. For the fighter application, ACC showed a significant net benefit in the high pressure turbine only.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1979
- Accession Number
- ADA080620
Entities
People
- E. J. Kawecki
Organizations
- Pratt & Whitney