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The full integration of the propulsion system is an important requirement for military aircraft in order to reduce their radar signature and to increase overall aerodynamic performance. This leads to short and highly bent engine intake ducts, which typically provoke severe flow distortions close to the compressor system. Especially in compact systems the flow within both the intake duct and the compressor interacts. In the last decades the intake duct and the compressor system have predominantly been designed separately . Nevertheless, the aerodynamic intake - compressor interactions have to be considered during the design of highly compact and thus aerodynamically coupled propulsion systems . The Institute of Jet Propulsion at the Bundeswehr University Munich hence developed a military engine intake duct specifically for research purposes. The research duct can be tested in both a remote - and close - coupled configuration with the Larzac 04 turbofan engine. Different types of adapters integrated within the duct 's structure enable extensive wall pressure measurements and moreover a flexible integration of flow control devices. This paper evaluates the commissioning of the research duct in several configurations. It is focused on, first, the initial design o f a passive flow control device, which serves as base design for further studies on flow control in the research duct. Second, time - resolved static wall pressure measurements at various positions reveal the unsteady character of the flow within the range of 0 . 21 < St < 0.26 , which is most probably relate d to a mass flow fluctuation

International audience ; Bent inlet configurations find their application within the field of civil and military aviation as well as in stationary gas turbines. The distorted flow in such ducts can have a major influence on the performance, stability, and durability of the gas turbine. Both experimental and numerical approaches are generally applied during the design and optimization of inlet systems. The last decade high fidelity numerical simulations became very popular in this field of research, however, experimental investigations are essential for the calibration, validation, and optimization of numerical simulations. Experimental data is moreover necessary to assess the influence of combined pressure-swirl distortions on the performance of the entire propulsion system. The Institute of Jet Propulsion made major efforts to integrate a highly complex inlet duct in a test setup with the state-of-the-art MexJET turbofan engine. This setup enables the assessment of combined pressure-swirl distortion and its influence on the engine and makes investigations on inlet-compressor interactions possible. This paper describes the six main project phases, which include the definition, design, development, and integration of this highly bent inlet system at the engine test bed of the Institute of Jet Propulsion.

Integrated propulsion plays a major role in future civil and military aircraft design. A key component of these systems are highly bent intake geometries. As the flow passes through such ducts, combined total pressure and swirl distortions are generated which have a negative impact on compressor performance, safety margin, and durability. Due to weight and space limitations, a close coupling of intake and compressor is necessary. An experimental test case including a highly bent intake geometry and a state of the art turbofan engine was established and extensive measurement data was acquired. This publication compares results of three different numerical approaches to this test data: Isolated intake simulations, isolated compressor simulations with distorted inflow conditions, and a coupled simulation of intake and three stage compressor. The isolated intake simulation is able to reproduce the static wall pressure field of the intake as well as the occurring flow separation. Towards the interface plane to the compressor however, significant deviations are observed. The upstream effect of the compressor working under the combined pressure swirl distortion is assessed via the second simulation approach. The influence of the swirl and total pressure distortion on the compressor is first simulated separately and than compared to the impact of the combined distortion. The coupled intake- compressor simulation reveals the manipulation of the intake flow field by an upstream static pressure field. In contrast to experiments a slightly unsteady operation point and an asymmetric intake flow field were observed