Aero–Thermo Analysis of a Waste Heat Recovery Heat Exchanger

Abstract

Abstract. This study investigates the aerothermal performance and flow dynamics of a heat recovery heat exchanger (HEX) for the Water Enhanced Turbofan (WET) cycle concept. A combined experimental and numerical approach is used to assess how flow turning influences heat transfer and pressure losses. The heat recovery unit comprises a radially distributed tube bank, with a length in excess of 2 m, downstream of the turbine exhaust. The tested 30 deg sector consists of 860 tubes. The selected heat recovery design, with the exhaust gases radially turned 90 deg and flowing through the tubes, results in a highly nonuniform flow posing significant challenges for accurate performance assessment. The experimental evaluation was conducted at Chalmers University using a 1:1 scale model operating under engine representative conditions. Numerical Reynolds-averaged Navier–Stokes (RANS) simulations were performed at GKN Aerospace Sweden using ansysfluent on a computational domain of 65 × 106 cells, with a detailed in-tube model for heat transfer evaluation. The overall aerothermal performance shows good agreement between experimental and numerical results; however, at a detailed level, notable discrepancies are identified. The effect of baffle spacing on flow stability and pressure loss distribution is discussed in detail. This study highlights the potential of the combination of relatively simple experimental configurations in combination with detailed numerical simulations to provide insights into nonstandard HEX configurations.