EFFECTS OF SURFACE WAVINESS ON FAN BLADE BOUNDARY LAYER TRANSITION AND PROFILE LOSS — PART II: EXPERIMENTAL ASSESSMENTS AND APPLICATIONS

Abstract Part II describes the experimental assessment and application of ideas in I concerning mechanisms that determine role blade surface waviness on laminar-turbulent transition their consequent effect civil aircraft fan performance. A natural wind tunnel was designed constructed to characterize impact transition, using both hotwire anemometry infrared thermography. The results support new hypothesis presented I, way which affects performance through motion onset location due interaction between Tollmien–Schlichting (TS) boundary layer instability. In particular, theoretical amplification TS waves, corresponding movement waviness, borne out over a range variations Reynolds number, nondimensional wavelength, wave height, initiation, relevant composite parameters. Further, increase receptivity coefficient, thus, initial amplitude disturbances geometric resonance wavelength also confirmed by experiments. Surface estimated, some cases, result nearly 1% decrease efficiency compared nonwavy blade. Suggestions are given for mitigation effects including idea curvature rescheduling as method delay thus loss.