| Autor: |
Robert P. Grewe, Robert J. Miller, Howard P. Hodson |
| Rok vydání: |
2014 |
| Předmět: |
|
| Zdroj: |
Volume 2C: Turbomachinery. |
| DOI: |
10.1115/gt2014-25326 |
| Popis: |
Turbine blades and vanes of modern aero-engines are commonly manufactured by casting. The casting process often introduces slight geometry variations. In the endwall region this leads to inter-platform steps, gaps and leakage flows. This paper determines the underlying loss mechanisms associated with each of these geometric features and guides designers in minimizing their impact on efficiency. The paper shows that the presence of an inter-platform step causes a pair of vortical structures to be superimposed onto the blade existing secondary flow structure. These are shown to always increase loss. When manufacture variations are considered the optimal design intent blade is shown to be one where the suction side endwall is lower than the pressure side endwall. The paper shows that when leakage mass flow is introduced the presence of a step can either raise or reduce loss. A correlation which gives the optimal step height for a set leakage mass flow is presented. In the final part of the paper measured engine vane geometries are used to determine the impact of endwall geometry variation on turbine stage efficiency. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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