The unsteady mid-span aerodynamics of an outlet stator row in a 1.5-stage low-speedudaxial compressor is investigated experimentally and numerically. Two stator bladeudrows with characteristically dierent blade proles are studied: one of standard BritishudC4 section and a controlled diusion (CD) blade with a circular arc leading edgeudprole.udA turbulence grid placed at compressor inlet is used to generate turbulence characteristicsudsimilar to those occurring in an embedded stage in a multi-stage axial compressor.udThe stator inlet udow is studied using hot-wire anemometry and comparedudwith previous measurements made in the natural low inlet turbulence conguration ofudthe research compressor. Increased turbulence level enhances the dispersion of inletudguide vane (IGV) wakes. This modies the interaction between IGV and rotor bladeudwakes, leading to a more circumferentially uniform udow eld at entry to the statorudwith signicantly lower periodic unsteadiness.udLaminar-turbulent transition on a C4 stator blade is studied using an array ofudsurface-mounted hot-lm sensors. Comparisons with measurements made at low inletudturbulence show that the increased inlet turbulence level reduces the extent of periodicudtransitional udow on the stator blade surface. The blade element behaviour udowudbehaviour at high inlet turbulence closely resembles the low inlet turbulence case withudthe stator immersed in IGV wake turbulence.udThe circular arc leading edge prole of the CD stator produces rapid accelerationudand deceleration at the stator leading edge. The inuduence of this velocity spike on theudstator boundary layer development and transitional udow behaviour is studied usingudan array of surface mounted hot-lm sensors. A region of favourable pressure gradientudon the suction surface following the leading edge spike has a stabilising eect on theudboundary layer, with a large region of udow in a laminar or transitional state. Turbulentudspots and instability phenomena in this region are examined for convection speed, growth rate and evidence of relaminarisation. In contrast, the udow on the pressureudsurface becomes turbulent near the leading edge. The study shows that compressorudblade leading edge proles have a major inuduence on boundary layer development overudthe whole surface.udThe eect of upstream rotor wake passing on the stability of stator blade boundaryudlayers is examined. The unsteady quasi-three dimensional udow solver, UNSFLO, isudused to interpret surface hot-lm data and unsteady laminar udow behaviour at theudleading edge of both C4 and CD stators. Rotor wake chopping is found to stabilise theudpressure surface boundary layer and destabilise the suction surface boundary layer.udExamination of hot-lm data points to the leading edge as the principal receptivityudsite for transitional udow phenomena occurring on the suction surface of both the C4udand CD blading.
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