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Film cooling is a widely used method to protect materials exposed to hot gases whose temperatures may exceed the melting temperature of the materials, for example in gas turbine engines used in aerospace and power generation.  Film cooling protects the material by injecting a layer of cooler air to insulate the material surface from the hot gas; however, it can be inefficient because film-cooling jets can lift off from the material surface that they are intended to protect and draw in or entrain hot gases underneath them.  As a result, the effectiveness of film-cooling jets can be greatly reduced just a short distance from where they are located.  To overcome this drawback, ISU researchers have develop a new design for preventing hot gas ingestion by film-cooling jets using flow-aligned blockers.  This design—which incorporates ridges on either side of the film cooling jet—results in only the cooler air or gases being entrained beneath the film-cooling jet as it lifts off.  Consequently, film cooling can be accomplished with much less cooling flow, increasing the efficiency of turbine engines.

• Film cooling is increased to a distance of 15 diameters downstream of the film-cooling jet injection hole when the flow-aligned blockers are present compared to 2 diameters when they are not.
• Enables film-cooling jets to be highly effective over a range of blowing ratios, including those at which lift-off takes place, and can extend the service life of turbine engines.