The experimental method associated with obtaining meaningful information from the hot-film anemometer signals in fully developed pulsating turbulent flow where the pulsations are sinusoidal in time is discussed. The results of a number of experiments in water reveal the nature of the longtime and short-time average velocity and pressure. Velocity measurements between 0.95 radii and the centerline demonstrate that the long-time average velocity distribution is coincident with that for steady turbulent flow at the same Reynolds number. Also, no significant differences between the longtime average axial pressure drop in the pulsating and steady flows were noted, although this requires further investigation in view of the increases in the Reynolds stress observed in pulsating air flow.
The distribution of the measured pulsating velocity component depends upon the dimensionless turbulent frequency. At the lowest values of the frequency, the profile is turbulent-like, while at higher values, the maximum in the velocity shifts from the centerline towards the wall and a uniform speed region exists over the central portion of the tube.
An eddy viscosity model displays many of the important characteristics of the observed pulsating velocity. Using the results of this model and the experimental observations, limits of the laminar frequency parameter which delineates the response of the flow are suggested.
Recordings of the instantaneous velocity signal suggest the short-time behavior of the axial turbulence intensity to be generally that of increasing during deceleration of the flow and decreasing during acceleration.
Lu, S.-Z.; Nunge, R. J.; Erian, F. F.; and Mohajery, M., "Measurements of Pulsating Turbulent Water Flow in a Tube" (1973). Symposia on Turbulence in Liquids. 123.
3rd Biennial Symposium on Turbulence in Liquids (1973: Sep., Rolla, MO)
Chemical and Biochemical Engineering
Article - Conference proceedings
© 1973 University of Missouri--Rolla, All rights reserved.