Effect of High Reynolds Number on the Behaviour of Large and Very Large Scale Motions in Fully Developed Turbulent Pipe Flow

The experimental investigation of fully-developed turbulent pipe flow is performed to study contribution of the coherent structures to the kinetic energy over a special range of high Reynolds numbers. The experiment is carried out in the pipe test facility located at Brandenburg University of Technology, Germany. One-dimensional spectral analysis is used to assess the structure behaviour in the outer region of pipe flow. The results of power and pre-multiplied spectrum of streamwise velocity indicate that the wavelength of very large scale motions (VLSMs) acquires 19 R , where R is the pipe radius, at the maximum Reynolds number range Re D = u b D /ν = 1 × 10 6 , where u b is the bulk velocity, D is the pipe diameter, and ν is the kinematic viscosity. At the same time, the large-scale motions (LSMs) have the extreme wavelength equal to 3 R over various Reynolds number ranges. According to the identified wavelength values, it is observed that contribution of the energy to the structures greater than 3 R carries 55% of the total kinetic energy.