On the use of very small pitot-tubes for measuring wind velocity

Abstract

A recent paper by Stanton and Marshall describes experiments made to determine the distribution of velocity close to the wall of a pipe through which air in a turbulent state is flowing. In order to measure the velocity of the air, Stanton used a very fine Pitot-tube placed in the pipe so that it faced the wind. There is plenty of evidence that Pitot-tubes used in ordinary aeronautical work do provide an accurate measure of wind speed, the excess of pressure inside the tube over that in the surrounding air being 1/2 pv 2 ,where is p is the density and v the velocity of the air. On the other hand, there are two factors which would lead one to expect that this law might not hold under the conditions which occurred in Stanton’s experiment.