Velocity distributions and normal stresses in viscoelastic turbulent pipe flow

Pitot tube readings in a viscoelastic turbulent stream are discussed thoretically, and are shown to be made up by a first normal stress contribution, an integral normal stress contribution, and a kinetic contribution. These three contribution are of comparable orders of magnitude. The integral of a Pitot tube scanning curve is shown to yield a momentum average factor of direct physical relavance. Experimental data show that the normal stress contributions are not negligible even in the central region of the pipe, although turbulent flow conditions were reached. Observed values of the relevant parameters are discussed.