Miniature five-hole pressure probe for measurement of three mean velocity components in low-speed flows

A miniature five-hole pressure probe is described which has a probe tip diameter of 1.22 mm. The probe was developed to measure three mean velocity components using a non-nulling procedure at individual locations in a curved channel where differential pressures are low, flow is three-dimensional and laminar, and spatial resolution and flow blockage effects are important considerations. Calibration coefficients are presented for Reynolds numbers based on probe tip diameter ranging from 80 to 400. Coefficients for yaw angle, pitch angle, total pressure and total minus static pressure are independent of Reynolds number within experimental uncertainties. Experimental details unique to the use of the miniature probe are also given along with distributions of mean velocity and mean vorticity over a portion of the 12.7 mm*508.0 mm cross section of a curved channel. At a Dean number of 119 (mean streamwise velocity approximately 1.2 m s-1), structural characteristics of Dean vortices are evident from contours of the streamwise velocity, the total pressure and the streamwise component of mean vorticity determined from secondary flow vectors.