Aero Engine Intercooling Optimization Using a Variable Flow Path

Paper in proceeding, 2015

Intercooling, as a way to higher overall pressure ratio (OPR) and more efficient gas turbines, has recently drawn a substantial attention to aero engine applications. In contrast to the stationary gas turbines, aero engine intercooler system installation is very challenging. The focus of current intercooling research is mostly on developing the intercooler and associated ducting system in a highly compact, low weight and low loss way. For aero engine applications, operating points such as take-off, top-of-climb and cruise result in different working conditions, and hence also in a varying intercooling demand. In a previous study carried out at Chalmers University, a two-pass cross flow intercooler concept with an auxiliary nozzle showed considerable improvement in cruise SFC [ISABE2013 1215]. To further optimize the intercooler for the cooling demand in different operating conditions, a variable flow path concept controlling the core flow at different flight phases, see Figure 1, is studied. The concept is designed for an intercooled geared large turbofan engine. Results indicate that, with half of the core flow passing through the variable flow path at cruise, a further reduction of 0.5% cruise SFC can be achieved for the intercooled geared engine, resulting in a total of 4.9% fuel burn reduction compared with an optimized advanced geared engine.