(57) In turbine blades used as nozzle guide vanes 2, 12, 22, 31 for turbine stages of
an engine there is a problem with respect to high lift vanes in that there may be
significant stagnation point migration about the pressure surface 13, 21, 32 of that
vane. In such circumstances, appropriate positioning of coolant flow apertures 11,
24, 34 for coolant film cooling of the vane is difficult. The present invention provides
on the leading edge a bulge ridge 37 which limits the range of potential movement
for the stagnation point 30 whilst retaining improved lift for higher engine performance.
The present invention has particular applicability with flows directed to the turbine
NGV which have a significantly variable swirl angle and therefore presentation to
the vane 31.
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