A study of turbulent flow in pipe contractions

An experimental study of turbulent water Jow through abrupt contractions was carried out in order to determine the detailedJow$eld. Wall static pressure measurements enabled the calculation of pressure loss coeflcients for a range of contraction area ratios from 0.13 to 0.67 over a Reynolds number range of 40000-200000. The effect of variations in contraction sharpness was also established. Measurements of mean velocities and turbulence intensities were made using a two-component laser Doppler anemometer for one area ratio of 0.332 to establish the detailedjow features. Key words: sudden contractions NOTATION contraction coefficient = (D~/D,)’ wall static pressure coefficient = p $ ( + p ~ :) pipe diameter pressure loss coefficient pressure loss Coefficient for a sharp inlet momentum enhancement factor kinetic energy enhancement factor wall static pressure contraction inlet radius pipe radius Reynolds number axial fluctuating velocity mean axial velocity radial fluctuating velocity mean radial velocity axial distance radial distance area ratio = ( D 2 / D 3) 2 Subscripts 1 large bore, upstream, pipe 2 vena contracta 3 small bore, downstream, pipe C, centre-line