Title page for ETD etd-01312009-063212
|Type of Document
||Johnson, Loren Patton
||Effects of freestream turbulence on turbine blade heat transfer in transonic flow
||Master of Science
|Diller, Thomas E.
|Nelson, Douglas J.
|Date of Defense
The effects of grid generated freestream turbulence on surface heat
transfer to turbine blades were measured experimentally. Time-resolved and
unsteady heat flux measurements were made with Heat Flux Microsensors at
two positions on the suction side of turbine blades. The experiments were
conducted on a stationary cascade of aluminum turbine blades for heated runs
at transonic conditions. Non-dimensional flow parameters were matched to
actual engine conditions including the design exit Mach number of 1.26 and the
gas-to-wall temperature ratio of 1.4.
Methods for determining the adiabatic wall temperature and heat transfer
coefficient are presented and the results are compared to computer predictions
for these blades. Heat transfer measurements were taken with a new, directly
deposited HFM gage near the trailing edge shock on nitrogen cooled blades.
The average heat transfer coefficient for Mach 1.26 was 765 W/(m2°C) and
matched well with a predicted value of 738 W/(m2 °C). Freestream turbulence
effects were studied at a second gage location 1.0 cm from the stagnation point
on uncooled blades. Results at this location show an increase in freestream
turbulence from 1 % to 8% led to a 15% increase of the average heat transfer
coefficient and also matched well with predictions. The fast response time of the
HFM illustrated graphically the increase in energy spectra due to freestream
turbulence at the 0 - 10kHz range. The heat flux turbulence intensity (Tuq) was
defined as another physical quantity important to turbine blade heat transfer.
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