Master of Science (MS)
In this study, heat transfer coefficient and film effectiveness distributions are investigated for a film cooling hole configuration that has inclined holes discharging into a tangential slot before interactions with the mainstream. The cylindrical holes are inclined 35° along the mainstream direction. The effect of coolant-to-mainstream blowing ratio is examined for M=0.5 and M=1.0. Different slot width to hole ratios and also the effect of hole exit condition (square edge and triangular edge) is considered. The mainstream velocity and free-stream turbulence intensity in the low speed wind tunnel are 9 m/s and 7% respectively and the mainstream Reynolds number based on hole diameter is around 7,100. The intent is to come up with an optimum hole exit geometry associated with low convictive heat transfer coefficient h. Also the adiabatic film effectiveness η should be as high as possible. For this purpose, different whole exit geometries were tested for an optimum shape. Heat transfer calculations were made to obtain the local values for h and η. The first case tested were the “normal” 35° with 0.5 inch diameter inclined hole. The second was the “slot” with height to hole diameter ratio (p/d) is 0.4 and width to hole diameter ratio (W/d) = 1.75. The third was the right shoulder with (W/d) = 1.375. The fourth and fifth cases are the “double shoulder” with (W/d)= 1.0 and the “angled” with a varying ratio (W/d). The angled is featured with 18° inclined right attachment. The results of all cases were referenced to the normal case as a baseline. The right shoulder case presented the best performance with a uniform jet scattering. The right shoulder geometry is more likely to protect and cool the blade than the normal geometry, as its total adiabatic film effectiveness was better than baseline case with factor of 1.4 and the total heat transfer coefficient was less than baseline case with factor of 0.08. This means it will exchange less heat and provide a better film.
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Release the entire work immediately for access worldwide.
Altorairi, Mohammed, "Film cooling from cylindrical holes in transverse slots" (2003). LSU Master's Theses. 2966.
Srinath V. Ekkad