If a high momentum core mass flow is released into a detuner, the developing shear layer between the core and its surrounding is causing momentum and energy transfer leading to entrainment of secondary air. This mechanism is called ejector effect and is utilized in many applications. But also in enclosed jet engine test facilities the hot and fast exhaust gas causes entrainment of secondary air. This can lead to substantial test cell depression which in turn can cause enormous mechanical loads on the facility structure. Particularly with regard to modern high-performance jet engines a fundamental understanding of the ejector effect is necessary to maintain safe testing and research operation. Because of the fact that investigations on the ejector effect with real jet engines are very extensive in costs and time, thus the Institute of Jet Propulsion of the University of the German Federal Armed Forces Munich has built a scaled model of the institute’s sea-level engine test bed to get further insight into the physics of the ejector effect. Subject of the presented paper is the numerical simulation of the flow through this simplified low-cost test-bed with special attention to the interaction of the primary and the secondary mass flow. Parallel conducted experimental investigations are published by Bindl et al. [1] in the accompanying paper. The numerical simulation includes intensive sensitivity analyses on input data required at boundary conditions which were not determined experimentally. Also simulations of different engine power settings ranging from idle to maximum power with three different detuner to nozzle area ratios (DNAR) have been conducted. This was made to investigate the influence of the geometrical configuration on the macro test cell aerodynamics as well as on the ejector effect quantification parameters like the entrainment ratio and the test cell depression (TCD). Since the corresponding setups have also been experimentally investigated a comprehensive validation of the capability of the numerical simulation in calculating the ejector effect in terms of qualitative and quantitative compliance is enabled.    «

If a high momentum core mass flow is released into a detuner, the developing shear layer between the core and its surrounding is causing momentum and energy transfer leading to entrainment of secondary air. This mechanism is called ejector effect and is utilized in many applications. But also in enclosed jet engine test facilities the hot and fast exhaust gas causes entrainment of secondary air. This can lead to substantial test cell depression which in turn can cause enormous me...    »