Laser Two-Focus Anemometry Investigation of the Flow Field Within a Supersonic Axial Compressor Rotor

Abstract

Laser anemometer measurements have been performed within and downstream of a supersonic single-stage high-pressure compressor. At design point and with standard upstream conditions the maximum relative Mach number varies from 1.3 at the tip to 1.1 at the hub. The stage total pressure ratio is 1.84 and the specific mass flow 180 kg/s/m2. The laser two-focus anemometer has been completely designed in the Laboratory; its originality being the use of a counting technique instead of the classical multichannel analyzer one. The data acquisition and reduction procedures are presented here. A comprehensive evaluation of the global flow-field is in the scope of this paper. For that, the intra-blade flow field is described and the shock pattern is discussed. Furthermore, the experimental results are compared with both inviscid and viscous three-dimensional numerical simulations. The viscous computation is based on the Navier-Stokes solution using a mixing length turbulence model. The good agreement observed in this last case shows off the necessity of taking into account the viscous effects in a supersonic compressor flow calculation.

Treatment of L2F anemometer measurement volume distortions created by curved windows for turbomachinery applications

“…The elapsed time between the two signals, representative of the time-of-flight of the particles (figure 2(b)), yields the particle velocity, calculated from the known distance between the focal spots. Because start and stop can be triggered by two different particles, the L2F data have to be treated statistically [7].…”