Heat transfer from a row of impinging jets to concave cylindrical surfaces

Starting from the first principles, and with one experimentally obtained parameter, an expression for stagnation heat transfer is derived, applicable to round, impinging jets. The results obtained with a row of air jets impinging on an electrically-heated surface in a small-scale setup characteristic of a typical turbine blade have been found compatible with the average heat transfer from a geometrically similar, steam-heated surface scaled up ten times, and comparable with the results of other investigators. These findings were linked to the flow fields likely to exist in the gas turbine blades, internally cooled by a row of round jets or a single jet of equivalent width. The magnitude of heat-transfer coefficients obtained here with impinging jets approaches that normally associated with forced convection of water and evaporative cooling.