A Numerical 3-D Model of a Trapezoidal Three-Hole Pneumatic Pressure Probe for Incompressible Flow

Pneumatic pressure probes are well-mature measuring devices to characterize both pressure and velocity fields for external and internal flows. The measuring range of a particular probe is significantly influenced by important factors, like its geometry, the separation angle between the holes, the holes tapping or even flow conditions like separation and stagnation points or the local Reynolds number. Ideally, every pressure probe must be specifically designed for the particular application where it is needed. However, this procedure requires a detailed calibration of the probe for the whole expected range of velocities and incidences. This implies an important cost in both economic terms and operating times. Thus, the definition of an accurate numerical model for the design and calibration of pressure probes at different flow conditions is particularly desirable for these purposes. The first step towards the establishment of this useful methodology is the development of a reliable model to predict numerically the probe measuring characteristics. Thus, in this paper a numerical 3-D model is presented to characterize the calibration of a three-hole pneumatic pressure probe. In particular, a trapezoidal geometry with a 60 degree angle between the holes is considered here. The simulation of the flow incidence is carried out using the commercial code FLUENT, analyzing the influence of different mesh densities and turbulence models. The complete set of numerical cases includes different flow velocities and several yaw angles. The numerical results have been validated using experimental results obtained in a calibration facility, focusing on the definition of a numerical tool for the design and calibration of three-hole pneumatic probes under incompressible flow conditions.