Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

Abstract

Blade row interactions affect compressor performance and durability. As design systems expand to account for these interactions, a better understanding of the underlying physics is necessary. In this paper, results from a vane clocking experiment in a three-stage compressor are discussed. Efforts are focused on the second stage, specifically the change in stator 2 wake profiles with respect to the placement of the stator 1 wake. The two clocking conditions presented position the wake from stator 1 at the leading edge of stator 2 and in the middle of the stator 2 passage. The time-accurate data are Fourier decomposed to determine the relative magnitudes of the frequencies in the spectrum. With data acquired at 50 circumferential locations spanning one vane passage for each clocking configuration, an enormous amount of data is collected, and a useful method for synthesizing this information is presented. Results show that, by placing the stator 1 wake at the leading edge of stator 2, the stator 2 boundary-layer response to the large incidence variations associated with the rotor 2 wakes is dampened, resulting in a thinner and more shallow stator 2 wake. Nomenclature CL LE = clocking configuration that positions stator 1 wake at leading edge of stator 2 CL MP = clocking configuration that positions stator 1 wake in the middle of the stator 2 passage f = frequency m c = corrected mass flow rate P o = total pressure R = rotor S = stator U = wheel speed V = flow velocity in the absolute reference frame = absolute flow angle = adiabatic efficiency