Two-phase transpiration cooling

The history of cooling technologies for gas turbines is briefly considered. It is pointed out that two-phase transpiration cooling offers significant benefits. A major incentive to study two-phase transpiration cooling is the thermodynamic benefit if fuel could be used as the transpiration coolant. The heat transfer problem in a transpired wall is composed of two matched subproblems, including the internal heat transfer between the coolant and the porous wall and the interaction of the transpired stream with the external boundary layer. An analysis of two-phase transpiration cooling is conducted, taking into account a model physical description, governing equations, regimes and modes of operation, and the two-phase range. On the basis of the analysis, two-phase transpiration is identified as a potentially-powerful cooling scheme for gas turbines. Moderate blade temperatures may be maintained in very high temperature gas streams without separating the boundary layer or incurring large aerodynamic or cooling penalties.