Hole Exit TI Measurements in Film Cooling Flows

The local turbulence intensity profiles at hole exit are also found to be highly sensitive to the film cooling length. In general, high coolant momentum correlates to low local turbulence. Film cooling with short holes (L/D=2.3 in figures) tends to have a great deal of its coolant mass distributed towards the upstream portion of and along the edges of the hole at the exit plane. In general, local turbulence levels in these regions are lowest. Film cooling through long lengths (L/D=7.0 in figures) though is characterized by more uniform profiles or those slightly favoring the downstream portion of the hole at exit. Local turbulence levels are lowest in high-coolant-momentum regions. All film cooling flows tend to have a large region of very high turbulence levels upstrem of the hole. These high levels (~50%) correspond to the coolant-freestream stagnation region. Precise turbulence levels over the hole exit, though, depend on the coolant-to-freestream blowing rates. Hole exit local turbulence intensity (u'/Ulocalx100) profiles for film cooling through short and long lengths (L/D=2.3 and 7.0) and at low and high (VR=0.5 and 1.0) blowing rates are provided below.

Low Blowing Rate (VR=0.5):

TI Distrib. TI Distrib.

High Blowing Rate (VR=1.0):

TI Distrib. TI Distrib.
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