History, Philosophy, Physics, and Future Directions of Aircraft Propulsion System/Inlet Integration

This work provides a historical perspective of the developments of propulsion system inlet/engine integration. The flow physics of inlet distortion are discussed, along with the stability effects on the engine compression systems. Throughout the document, both commercial and military applications are considered. Developments in analyses from the original works characterizing inlet distortion, the use of distortion descriptors and early modeling concepts, and the modeling and simulation required today are reviewed. The special requirements and testing techniques necessary to adequately describe inlet distortion and the effects on the propulsion system are summarized. The aspects of pressure distortion, temperature distortion, and swirl are addressed and the physics of interaction described. The compression system response to different types of distortion is discussed with the interaction with various compression system components and designs explained. Axial and centrifugal compressors are covered, as the resulting physics of the inlet distortion effects on each has a different characteristic. An overview of the necessary flow physics to consider in the integration of compression systems in both low and high-Mach number applications is presented.