SAE ARP6420

The turbine-engine-inlet flow distortion descriptors summarized in this document apply to the effects of inlet total-pressure, planar-wave, and total-temperature distortions. Guidelines on stability margin, destabilizing influences, types and purposes of inlet data, AIP definition, and data acquisition and handling are summarized from AIR5866, AIR5867, ARP1420, and AIR1419. The degree to which these recommendations are applied to a specific program should be consistent with the complexity of the inlet/engine integration. Total-pressure distortion is often the predominant destabilizing element that is encountered and is often the only type of distortion to be considered, i.e, not all types of distortion need to be considered for all vehicles. The SAE S-16 Turbine Engine Inlet Flow Distortion Committee has developed an Aerospace Recommended Practice (ARP) and Aerospace Information Reports (AIR) describing measurement stations and techniques, and descriptors for different types of inlet total-pressure, planar-wave, and total-temperature distortion. There has been broad acceptance of these descriptors by the industry. Although a treatment for swirl distortion has been proposed, no methodology for swirl distortion has gained wide acceptance. When an accepted methodology exists for swirl distortion, this document will be updated to include it. This document provides a single source that contains the recommended measurement stations and techniques, and descriptors for total-pressure, planar-wave, and total-temperature inlet distortion.