Vane Clocking Effects on Stator Suction Side Boundary Layers in a Multistage Compressor

Natalie R Smith,Nicole L Key

doi:10.1155/2016/5921463

Natalie R Smith, Nicole L Key

Open Access

https://doi.org/10.1155/2016/5921463

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Abstract

The stator inlet flow field in a multistage compressor varies in the pitchwise direction due to upstream vane wakes and how those wakes interact with the upstream rotor tip leakage flows. If successive vane rows have the same count, then vane clocking can be used to position the downstream vane in the optimum circumferential position for minimum vane loss. This paper explores vane clocking effects on the suction side vane boundary layer development by measuring the quasi-wall shear stress on the downstream vane at three spanwise locations. Comparisons between the boundary layer transition on Stator 1 and Stator 2 are made to emphasize the impact of rotor-rotor interactions which are not present for Stator 1 and yet contribute significantly to transition on Stator 2. Vane clocking can move the boundary layer transition in the path between the wakes by up to 24% of the suction side length at midspan by altering the influence of the Rotor 1 wakes in the 3/rev modulation from rotor-rotor interactions. The boundary layer near the vane hub and tip experiences earlier transition and separation due to interactions with the secondary flows along the shrouded endwalls. Flow visualization and Stator 2 wakes support the shear stress results.

Highlights

Blade row interactions in a multistage axial compressor affect stage performance, unsteady blade loading, and acoustic signatures
While the circumferential position of the upstream wake with respect to the downstream vane is certainly affected by vane clocking, Smith et al [17] showed that the radial penetration of the tip leakage flow from the upstream rotor changed across the downstream stator pitch due to the interaction between the upstream vane wake and the upstream rotor tip leakage flow
The pitchwise variations in the flow field associated with vane clocking include the upstream vane wakes, and differing rotor tip leakage flow structures

Summary

Introduction

Blade row interactions in a multistage axial compressor affect stage performance, unsteady blade loading, and acoustic signatures. Vane clocking affects stage efficiency [8,9,10,11], unsteady blade loading [12, 13], and acoustics [14,15,16]. In research facilities where vanes can be individually positioned, vane clocking is a useful tool to investigate blade row interactions. While the circumferential position of the upstream wake with respect to the downstream vane is certainly affected by vane clocking, Smith et al [17] showed that the radial penetration of the tip leakage flow from the upstream rotor changed across the downstream stator pitch due to the interaction between the upstream vane wake and the upstream rotor tip leakage flow. The pitchwise variations in the flow field associated with vane clocking include the upstream vane wakes, and differing rotor tip leakage flow structures

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