Date of Award

2015

Document Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Mechanical and Aerospace Engineering

Committee Chair

Phillip Ligrani

Committee Member

Keith Hollingsworth

Committee Member

Jason T. Cassibry

Subject(s)

Cross-flow (Aerodynamics), Gas-turbines--Combustion., Turbomachines--Design and construction.

Abstract

Experimental results are presented for a double wall cooling arrangement which simulates a portion of a combustor liner of a gas turbine engine. The results are collected using a new experimental facility designed to test full coverage film cooling and impingement cooling effectiveness using either cross flow, impingement, or a combination of both to supply the film cooling flow. The present experiment primarily deals with cross flow supplied full coverage film cooling for a sparse film cooling hole array that has not been previously tested. Data are provided for turbulent film cooling, contraction ratio of 1, blowing ratios ranging from 2.78 to 4.94, coolant Reynolds numbers based on film cooling hole diameter of 7,000 – 12,000, and mainstream temperature step during transient tests of 7 ºC to 10 ºC. The film cooling hole array consists of a film cooling hole diameter of 6.4 mm with non-dimensional streamwise (X/d_e) and spanwise (Y/d_e) film cooling hole spacing of 15 and 4, respectively. The film cooling holes are streamwise inclined at an angle of 25 degrees with respect to the test plate surface and have adjacent streamwise rows staggered with respect to each other. Data illustrating the effects of blowing ratio and main flow velocity on adiabatic film cooling effectiveness and heat transfer coefficient are presented. For the arrangement and conditions considered, heat transfer coefficients generally increase with streamwise development, and increase with increasing blowing ratio. The adiabatic film cooling effectiveness is determined from measurements of adiabatic wall temperature, coolant stagnation temperature, and mainstream recovery temperature. The adiabatic wall temperature and adiabatic film cooling effectiveness generally decrease and increase, respectively, with streamwise position, and generally decrease and increase, respectively, as blowing ratio becomes larger.

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