The role of unmanned aerial systems (UAS) is becoming increasingly important in aerospace development across a range of disciplines. The integration of complete engines into aircraft fuselages, along with highly curved intake ducts, offers significant advantages due to their compact size and minimal impact on structural weight. A compact intake design can lead to substantial flow distortions and negatively affect the performance and flow stability of the engine. Today’s industry practice for flow distortion quantification in propulsion system integration relies on isolated pressure measurements at the engine front. Recent studies have shown that this low-accuracy approach is not adequate to complex future aircraft designs, as these assessment methods cannot capture pertinent features of flow distortion. Traditional distortion descriptors like the can provide a simplified total pressure distortion based on a 60-degree weighted angular section. More complex distortion patterns beyond the coverage of these sections are underrated. The phenomena arising from the instability of secondary flows cannot be captured adequately by traditional descriptors. Frequencies associated with certain flow distortion phenomena significantly affect the engine fan’s response. This study uses additional newly defined flow distortion descriptors to close these gaps, such as the area integral of the secondary kinetic energy or the resulting load of the wall pressure distribution at the aerodynamic interface plane. Using the coefficient for the secondary vorticity also makes it possible to identify the dominant frequencies of the vortex systems that occur in the coupled intake system and affect the engine. The coupling shifts the first mode of the central flow separation from 15.7 to 25.1 Hz and introduces a new 75.2 Hz mode. A dominant 150.4 Hz mode, close to the measured 153 Hz is also found. The results demonstrate that advanced, time-resolved distortion metrics enable an effective analysis of intake–compressor interaction and are therefore essential for evaluating highly integrated propulsion systems.     «

The role of unmanned aerial systems (UAS) is becoming increasingly important in aerospace development across a range of disciplines. The integration of complete engines into aircraft fuselages, along with highly curved intake ducts, offers significant advantages due to their compact size and minimal impact on structural weight. A compact intake design can lead to substantial flow distortions and negatively affect the performance and flow stability of the engine. Today’s industry practice for flo...     »