Blade Turbines cooling concepts

Different cooling concepts are used for the adjustment of the heatbalance in the blades. Illustration 2a shows a hollowpoured turbine blade with complex internal cooling structure. 

In high-temperature gas turbines cooling systems need to be designed for turbine blades, vanes, endwalls, shroud, and other components to meet metal temperature limits. The concepts underlying the following five basic air-cooling schemes are (Figure 9-13) ... 

The patent filed in 1991 by the United States Air Force (Anon, 1991) comes close to the concept which allowed the subject of this study to germinate. The USAF proposed a hollow gas turbine rotor blade with a catalyst coated on the inner surface. The cooling would be effected by vaporisation and decomposition of an endothermic fuel introduced into the hollow blade. The concept is illustrated in Figure 8.13. The endothermic fuel is defined as one which is liquid and which decomposes in the presence of a catalyst into two or more gaseous compounds different chemically from the liquid. At least one of the gaseous compounds is, of course, combustible in this case. The liquid fuels covered in the patent include methylcyclohexane, methanol, n-heptane or JP7 (kerosene fuel). An additional feature of using a liquid fuel as the feedstock is that latent heat of vaporisation contributes to cooUng, in addition to the endothermic reaction. 

---