Aerodynamic probes are prevalent in turbomachinery research and gas turbine monitoring. Regrettably, this measurement technique experiences limitations in the transonic range as well as high frequency. Calibrated numerical tools offer an alternative procedure to design suitable instrumentation for each turbine application. In this paper, all the numerical analyses were performed using unsteady Reynolds Averaged Navier Stokes (URANS), two and three-dimensional.

Firstly, two different probe geometries, oval and trapezoidal probe geometries were characterized at different incidence angles. In particular, the pressure recovery, angle sensitivity, induced vortex shedding unsteadiness at several yaw angles were evaluated. The studies were performed over a wide range of Mach numbers from subsonic to the transonic regime. The vortex shedding of the probe was also carefully analyzed. In a second evaluation, we selected the oval probe geometry including the line-cavity effects into the pressure tappings. The resonance frequency of line-cavity system was evaluated and compared with analytical calculations, as well as with the detailed analysis of Bergh and Tijdeman. The comparison of the pressure tapping readings with the actual input signal allowed the identification of the transfer functions, as well as the physical mechanisms that should be corrected during the measurements. Finally, 3D unsteady evaluations were implemented to compute the blockage effects, as well as the final frequency attenuation experienced by the piezo-resistive sensors.

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