Optimisation techniques for combustor wall cooling

In a drive to increase the thermal efficiency of modern gas turbine engines, the turbine entry temperature (TET) has been steadily increasing over time to the point where the hot gasses contained within the combustion chamber have temperatures well in excess of the melting point of the materials used in its construction. As a result compressor exit air is widely used to cool these components. However, the use of this air is detrimental to the cycle efficiency. Therefore an important area of study is in optimising the use of this cooling flow in order to minimise the amount of air diverted from the main cycle. Effusion cooling techniques involving the use of a number of holes arrayed on the combustor liner wall are widely used and with additive manufacturing techniques such as direct laser deposition (DLD) gaining maturity, the design space of the cooling passages has become much wider. Therefore methods of assessing the performance of these newly enabled designs must be developed. [Continues.]