Effects of Dilution Jet Placement and Resulting Coherent Structures on Turbine Flow Fields and Heat Transfer

Open Access
Author:
Della Corna, Enrico Bartolo
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Stephen P Lynch, Thesis Supervisor
  • Hosam Kadry Fathy, Honors Advisor
Keywords:
  • dilution jet
  • vane flow fields
  • vane heat transfer
  • computational model
Abstract:
A key to increasing performance of high power gas turbine engines is improved understanding of crucial components such as the combustion chamber and first vane cascade. While these systems provide a significant portion of the engine’s power, there are many intricacies to their interactions which are not fully understood. Dilution jets are introduced to the combustion chamber to help create uniform exit flow and aid fuel-air mixing. However, unsteady flow structures result from these jets entering the crossflow and lead to uneven velocity and temperature profiles at the combustor exit. A large body of prior work exists which characterizes flow within the combustion chamber both experimentally and computationally. This is also true of work regarding flow and heat transfer at the turbine first vane. Less research exists that focuses on the interaction between the large-scale structures created by dilution jets and their direct impact on the first vane. This work created computational models of a standard combustor setup as well as two similar configurations that varied the placement of the dilution jets in relation to the first vane. A steady RANS model was used to simulate turbulent flow through each setup. The resulting models determined that dilution jet placement could influence heat transfer levels on the first vane. Decreasing the stream-wise distance between the dilution holes and the first vane created large velocity gradients at the turbine inlet, and subsequently produced highly varied heat transfer at different regions along the first vane. Shifting the holes to create alignment of the second row of jets and the vane leading edge appears to induce lower and more even heat transfer on the vane surface, calling for further investigation of this design.