Statistical measurements of turbulence in the flow of air through a pipe

Numerous method have been used to investigate experimentally the turbulence arising in a moving fluid from the boundaries confining it or the bodies immersed in it. Many of these only give qualitative information, whilst of these which yield numerical results most are rather incomplete in the amount of information they give about the distribution of the turbulent velocity components and their relation to one another. In the present case the problem has been attacked by a method which enables small masses of air to be identified and their individual motions observed. Cinematography records of these motions, and their subsequent analysis, allow quantitative results to be obtained in statistical from showing the magnitude of the mean turbulence at any point in a field of flow and its distribution over the field. The maximum values of the turbulent velocities and the average resultant velocity are also obtained in the process.