Flow in a commercial steel pipe

Fully-developed turbulent flow in a commercial steel pipe is studied using single component hot-wire probes in both one and two-point experiments. The stream wise turbulence component was measured over a Reynolds number range from 7.6× 10 ⁴ to 8.3×10 ⁶, covering the smooth to fully rough regimes. The experiments were conducted in the Princeton/ONR Super pipe facility that uses compressed air at pressures up to 200 atm as the working fluid. For Reynolds numbers less than about 8 ×10 ⁵ the surface was hydraulically-smooth, and the results agreed closely with the smooth-wall turbulence intensity and spectral data obtained by Morrison et al. [10] and Zhao & Smits [14]. An assessment was performed of probe resolution and results indicate that the turbulence statistics of the large-scale motions were unaffected by the sensing wire length even at high Reynolds numbers. Transitionally-rough and fully-rough data showed deviation from the smooth-wall data as roughness effects became more prominent. In particular, the outer peak in the turbulence intensity observed at high Reynolds numbers in smooth pipe flow decreased in magnitude or stayed constant for transitionally rough and fully rough flow. The two-point azimuthal correlations were found to be consistent with the presence of very large scale coherent regions of low-wavenumber, low-momentum fluid observed in previous studies of wall-bounded flows. The correlations indicated that the azimuthal scale of these regions is Reynolds number independent.