The design and optimization of an integrated airframe-propulsion system is a main focus of current research at the Institute of Jet Propulsion at the University of the German Federal Armed Forces in Munich. Hence, extensive experimental investigations are planned at the engine test facility of the institute. An unconventional air inflow is caused by the particular design of this facility. The flow does not enter the test cell horizontally, but it is guided through an inlet tower. It is crucial to understand the influence of this specific inflow on the aerodynamics within an integrated inlet duct before expensive testing campaigns are started and thus, in a first step, investigations are performed with a scaled model of the engine test bed. This enables time and cost efficient studies with a wide range of parameters. In combination with detailed numerical studies the understanding of complex flow phenomena can be improved even further. The current work mainly focusses on the determination of total pressure distortion at the aerodynamic interface plane of a jet engine in different experimental set-ups. Pressure distortion analysis is generally of interest for investigations related to integrated inlet systems. First, the characteristics of the duct should be quantified with distortion descriptors to evaluate its influence on a safe operation of the engine. Second, in specific set-ups pressure distortion measurements are necessary for a precise calculation of the engine mass flow. The latter is required for engine performance analyses and the validation of numerical studies. Mass flow measurement is generally a challenge at an engine test bed even if a bellmouth airmeter is used. Considering the specific inflow condition and the aerodynamic behavior inside the test cell under consideration here, the total pressure distribution inside the inlet duct is distorted by definition. The inlet configuration currently under investigation consists of a complex geometry and hence an airmeter cannot be installed. This makes an accurate determination of the mass flow even more challenging. The approach chosen here starts with a fundamental comparison between an axial air inflow and an angled inflow condition as it occurs in the engine test facility. The set-up consists of a jet engine with a bellmouth airmeter. In a second step, experiments with an integrated inlet and an axial inflow condition are conducted. The aerodynamic conditions within the inlet duct and at the aerodynamic interface plane are analyzed. In this case analysis is supported by numerical investigations. In a third step, the complexity is increased even further by combining the first and the second set-up. The influence of the angled inflow, evoked by the inlet tower, on the flow within the integrated inlet is investigated. In all three cases, measurements are conducted at a wide range of engine operating points in order to quantify the impact of the flow distortion with distortion descriptors.    «

The design and optimization of an integrated airframe-propulsion system is a main focus of current research at the Institute of Jet Propulsion at the University of the German Federal Armed Forces in Munich. Hence, extensive experimental investigations are planned at the engine test facility of the institute. An unconventional air inflow is caused by the particular design of this facility. The flow does not enter the test cell horizontally, but it is guided through an inlet tower. It is c...    »