Experiments in high reynolds number turbulent pipe flow

An experimental facility was constructed to investigate fully-developed turbulent pipe flow over an unprecedented range of Reynolds numbers (approximately 32 x 10³ to 35 x 10⁶ based on average velocity and diameter). The maximum Reynolds number investigated exceeds the highest previously measured by an order of magnitude. To attain high Reynolds numbers at reasonable cost, compressed air (up to 220 aim} was used as the working fluid. The results show that the friction factor depends on Reynolds number logarithmically, as proposed by Prandtl, but a set of new constants are found. The friction factor data show von Kármán's constant to be 0.44. If the velocity profile is normalized using inner scaling variables, a log-law with this slope and an additive constant of 6.3 is in excellent agreement with the data. If the velocity profile is normalized using outer scaling variables, a log-law with this slope and an additive constant of 1.5 is in good agreement with the data. It is also shown that the average velocity occurs at a location approximately 1/4 radius from the wall, independent of Reynolds number.