Date of Award

12-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Aerospace, Physics, and Space Sciences

First Advisor

Mark Archambault

Second Advisor

James Brenner

Third Advisor

Gerald Micklow

Fourth Advisor

Daniel Batcheldor

Abstract

The objective of this study was to evaluate the effect of the cooling hole size on the adiabatic film cooling effectiveness over a rotating turbine blade section. The study was conducted using ANSYS FLUENT to determine the adiabatic wall temperature over the blade surface. The geometry was created to be a single section of a turbine rotating at 4000 rpm, and the blade increases in camber from tip to hub. Cylindrical cooling holes were created and the diameters were varied from 0.5 mm to 1.5 mm. The pitch-to-diameter ratio and the length-to-diameter ratio were kept constant at a value of 3. An unstructured mesh was generated for the geometry, and an inflation layer was created to capture the boundary layer around the blade surface. The Shear-Stress Transport k-ω turbulent model was used with the curvature correction and production limiter. The velocity boundary condition for the flow entering the domain was set such that the angle with respect to axial direction was the same as the angle-of-attack of the blade. Therefore, the velocity components in the y−direction and the z−direction were set to values of -128.56 m/s and 153.21 m/s, respectively, and the temperature was set such that T The objective of this study was to evaluate the effect of the cooling hole size on the adiabatic film cooling effectiveness over a rotating turbine blade section. The study was conducted using ANSYS FLUENT to determine the adiabatic wall temperature over the blade surface. The geometry was created to be a single section of a turbine rotating at 4000 rpm, and the blade increases in camber from tip to hub. Cylindrical cooling holes were created and the diameters were varied from 0.5 mm to 1.5 mm. The pitch-to-diameter ratio and the length-to-diameter ratio were kept constant at a value of 3. An unstructured mesh was generated for the geometry, and an inflation layer was created to capture the boundary layer around the blade surface. The Shear-Stress Transport k-ω turbulent model was used with the curvature correction and production limiter. The velocity boundary condition for the flow entering the domain was set such that the angle with respect to axial direction was the same as the angle-of-attack of the blade. Therefore, the velocity components in the y−direction and the z−direction were set to values of -128.56 m/s and 153.21 m/s, respectively, and the temperature was set such that T∞ = 1800 K. The velocity boundary conditions at the hole inlets were calculated such that the mass flow rates on the suction and pressure = 1800 K. The velocity boundary conditions at the hole inlets were calculated such that the mass flow rates on the suction and pressure sides were 0.00384 kg/s and 0.01295 kg/s, respectively. The temperature boundary condition at the hole inlets was calculated to be 973.86 K. A quantitative analysis was performed using the exported temperature data, where the laterally-averaged effectiveness was plotted against the non-dimensional position, z/c. Qualitative analysis was also performed by observing the temperature distributions on the blade surface, as well as the velocity streamlines from the inlets of the film cooling holes. Streamlines colored by Mach number were used to ensure flow remained subsonic. Based on the results, the increase in the hole size improved the distribution of the effectiveness downstream from the holes on the pressure side, but had minimal effect on the effectiveness on the suction side. An increase in the cooling hole size caused an increase in the spreading of the coolant from the cooling hole exits over the blade surface. On the pressure side, the slope on the effectiveness plots for the larger angles show that the amount of cooling remains almost the same along the blade’s axial position.

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