Computational Evaluation of Turbo- and Electric-Powered Simulators for Turbofan Wind Tunnel Test

Experimental testing of aircraft configurations requires the use of representative engine units to simulate powered-on conditions. For ultra-high-bypass-ratio engines featuring tighter aircraft integration, the installation effects need to be carefully assessed. This paper presents a computational evaluation of two powered simulator models for wind tunnel tests of an ultra-high-bypass-ratio turbofan, based on a traditional air-driven turbo-powered simulator (TPS) and an electric-powered simulator (EPS). Starting from two-dimensional axisymmetric analyses, the design of the baseline turbofan engine and the choice of the duplication parameters of the simulators are described. Several aspects related to the nonreproducibility of the core flow at wind tunnel level are discussed, in terms of mass flow matching, TPS core nozzle pressure ratio, and plug shape of the EPS. The EPS can provide a more faithful reproduction of the flowfield under installation, with an estimated installation drag from 4 to 2 drag counts lower than the reference geometry, compared to the 6 drag counts higher prediction of the TPS.