Simulations of Multi-Phase Particle Deposition on Film-Cooled Turbine Sections

Open Access
- Author:
- Lawson, Seth A
- Graduate Program:
- Mechanical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- January 19, 2011
- Committee Members:
- Karen Ann Thole, Dissertation Advisor/Co-Advisor
Cengiz Camci, Committee Member
Karen Ann Thole, Committee Chair/Co-Chair
Domenic Adam Santavicca, Committee Member
Savas Yavuzkurt, Committee Member - Keywords:
- adiabatic effectiveness
heat transfer
gas turbine
particle deposition - Abstract:
- The demand for clean, efficient energy has driven the motivation for improving the performance standards for gas turbines. Increasing the combustion temperature is one way to achieve the best possible performance from a gas turbine. One problem associated with increased combustion temperatures is that impurities ingested in the fuel and air become more prone to deposition with an increase in turbine inlet temperature. Deposition on aero-engine and land based turbine components caused by particle ingestion can impair turbine cooling methods and lead to reduced component life. It is necessary to understand the extent to which particle deposition affects turbine cooling in regions where heat transfer from the hot gases to the cooled turbine components is most critical. For this study, a novel approach was developed to dynamically simulate particle deposition on turbine component models such that the effects of deposition on film-cooling were quantified. To simulate both solid and molten particulate matter in the hot gas path, low melting temperature wax was injected into the mainstream gas path of a low speed wind tunnel used to test film-cooling effectiveness on turbine cascade models. Results showed deposition could reduce film-cooling effectiveness by as much as 30% depending on cooling condition, particle phase, and location of cooling holes. Cooling effectiveness after deposition decreased with an increase in blowing ratio on the airfoil pressure side and leading edge. For all endwall cooling configurations tested, effectiveness after deposition increased with an increase in blowing ratio. Experiments were also conducted to determine if film-cooling geometries could be modified to mitigate the negative effects of deposition. Various configurations were tested and results showed that embedding cooling rows in transverse trenches could reduce the negative impact of deposition on cooling effectiveness. With the use of trenches, the maximum effectiveness reduction caused by deposition was 15% as compared to 30% with no geometric modification. Deposition was simulated in a film-cooled turbine cascade model with and without endwall contouring. Experimental results showed that strategic placement of cooling holes on a contoured endwall could prevent deposition around film-cooling holes and thus mitigate the negative effects of deposition on cooling-effectiveness.