UPSTREAM VELOCITY PROFILE EFFECTS ON ORIFICE FLOWMETERS

The effects of upstream velocity profile on the performance of orifice flowmeters were studied. Non-swirling maldistributed axial velocity p rofiles were obtained using a concentric pipe flow conditioner. Orific e flowmeters with beta ratios of 0.43, 0.50, 0.60, 0.70 and 0.75 were installed downstream of the flow conditioner and operated at a Reynold s number of 54 700 in a 50.4 cm pipe. Increasing the flow along the ce ntreline of the pipe decreased the pressure drop across the orifice pl ate, resulting in increased discharge coefficients. The opposite was o bserved as the flow along the pipe centreline was decreased. The error s increased with increasing beta ratio. A swirl generator was installe d upstream of the beta = 0.43 and 0.50 orifice plates. The swirl produ ced effects opposite to the axial velocity. The change in discharge co efficient increased with decreasing beta ratio.