A remark concerning engine-inlet distortion.

T effect of inlet d'stortion on axial compressor performance is both a current and complex problem. During the past 15 years the problem has been tackled by many investigators at both a practical engineering level and, for certain simplified geometries, at a sophisticated mathematical level. The essential stumbling block to predicting and controlling nonuniform and nonsteady flows into the compressor is lack of a suitable analytical framework upon which to base understanding of full-scale multistage compressor aerodynamics. In view of this handicap, NACA undertook an extensive experimental investigation of the problem in the early 1950's. Reference 1 is one of the last reports of these tests, and contains a bibliography of much of the earlier NACA efforts. Beginning to appear at about this time were several analytical examinations of nonaxisymmetric inflow, based primarily on the actuator disk model of a compressor blade row. The work of Katz is merely one example of this approach. Reference 3 is a more recent analysis containing an extensive bibliography of similar efforts. It is unfortunate that the comprehensive experimental efforts of Ref. 1 and the theoretical analysis of Ref. 2 were published about the same time. The references of