Flow Visualization of Low Aspect Ratio Pin Fin Arrays

Open Access
Author:
Haydt, Shane Elliott
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Karen Ann Thole, Thesis Supervisor
  • Henry Joseph Sommer Iii, Honors Advisor
Keywords:
  • heat transfer
  • turbomachinery
  • convective cooling
  • flow visualization
  • pin fins
Abstract:
Convective cooling technologies are applied often in thermal systems. Thermal management is important for the life of parts and for the efficiency of systems. Pin fins are one of these cooling technologies, and are used to promote heat transfer by increasing surface area and increasing turbulence. Pin fins are commonly used in gas turbines, especially in the blades of a high pressure turbine. The conditions of the flow around the blades in this section of the gas turbine are so intense that pin fins are needed to cool the blades and to provide structural support to the trailing edge of a turbine blade. This study examines how the arrangement of these pin fins affects the flow field around the array. Using a paint and oil mixture for flow visualization, pin arrangements with varying spanwise and streamwise spacing are studied and analyzed. The spanwise spacing is varied from S/D = 2 to 3, and the streamwise spacing is varied from X/D = 2 to 3. All experiments were run at a Reynolds number of 10,000 with low aspect ratio pin fins with H/D = 1. The results show that as spanwise spacing decreases, pressure loss increases. Streamwise spacing has no effect on the pressure loss. However, streamwise spacing does determine how large the wake is behind pins, and how much vortex shedding there is in the flow. These results corroborate and explain previously published heat transfer data.