An intercooled turbofan engine has been proposed within NEWAC (New Aero Engine Core Concepts, an European Sixth Framework Programme) using lightweight heat exchangers. The requirement for compactness has led to the need for zigzag heat exchanger arrangement where the heat exchanger matrices are inclined to the cooling flows approaching them, but such an arrangement creates non-uniform mass flows through the cold fluid side intercooler ducting and the intercooler heat exchanger matrices. Design guidelines aimed at minimizing aerodynamic losses caused by the flow mal-distribution in such ducting is reported. Minimising the loss has the effect of optimising the heat transfer performance. Flow velocities and pressure distributions were measured experimentally in a simplified model of a heat exchanger and simulated in Computational Fluid Dynamics (CFD). Good agreement was found between measurement and predictions of the flow distribution in the cold fluid side intercooler ducting downstream of the heat exchanger matrices. A dominant jetting flow in the centre of each exit passage was identified as a source of aerodynamic loss. The CFD simulation has also shown that the main source of aerodynamic loss arises from the severe flow mal-distribution within the heat exchanger matrices. From these results, design guidelines are presented in this paper for the ducting, based on CFD studies on a series of simplified heat exchanger arrangement geometries.
Feasibility study for an advanced coal fired heat exchanger/gas turbine topping cycle for a high efficiency power plant
