E. Rune Lindgren

Propagation Velocity of Turbulent Slugs and Streaks in Transition Pipe Flow

Taking account of experimental observations on the transition process, an elementary theory is developed for estimation of propagation velocity of the rear end of turbulent slugs and streaks which constitute a major feature of the transition process in pipe flow. The theory gives a lower propagation velocity than observed experimentally within the lower range of transition Reynolds numbers while at higher Reynolds numbers the theory gives a value about 7% higher than obtained experimentally. These deviations are due to approximations in the analysis which cannot be avoided at the present level of information on the structure of turbulent shear.

Evaluation of stereoscopic trace particle records of turbulent flow fields

An experimental technique is described for the recording of instantaneous spatial functions of particles tracing the motion in liquid flow fields. Software development necessary for subsequent computerized numerical evaluation of the instantaneous, three‐dimensional flow field also is described. The paper reports only the first stages of software development, in which descriptions are obtained of the detailed structure of turbulence events over whole flow regions simultaneously.

Annular pipe flow subject to axial motion of the inner boundary

This is an initial study concerning the stability of annular flow and the establishment of fully developed turbulent flow under conditions of various axial velocities of the inner surface. Both laminar and turbulent flow are characterized experimentally and theoretically.

Experiments on the structure of turbulent shear in pipe flows of water

A trace particle method by which three‐dimensional turbulent velocity fields can be pictured in great detail both qualitatively and quantiatively is described.

Average Velocity Distribution of Turbulent Pipe Flow with Emphasis on the Viscous Sublayer

A comprehensive experimental investigation is presented of the average velocity distribution of fully developed, smooth turbulent flows through straight pipes of circular cross section with special regard to the distribution within the viscous sublayer, including data at zero distance from the wall. The measurements seem to remove uncertainties and discrepancies inherent from earlier investigations. Current concepts of the universal velocity distribution are confirmed and verified.

Application of the Hot‐Film Technique on Flow of High‐Polymer Solutions

Exploratory measurements have been made to evaluate the hot‐film technique for flows of water with high molecular weight additives. Even a minute amount of additives considerably influence the heat transfer characteristics of the hot‐film probe.

Note on the Falling Cylindrical Shell Viscometer

A simple theory is presented according to which forces appear which tend to center the cylindrical shell in the fall tube of a falling cylindrical shell viscometer. This same result essentially should be obtained also for the falling cylinder viscometer, which necessarily must obey the same general principles but is more complicated in the analytical manipulations.

Two‐dimensional Hartmann flows of fluids with cross‐stream dependent electrical conductivity

The equations for two‐dimensional Hartmann flow through ducts of rectangular cross section are solved numerically by the Peaceman–Rachford alternating direction implicit method for boundary conditions appropriate to those encountered in a Faraday magnetohydrodynamic generator. Cross‐stream variation in fluid electrical condictivity as well as variable conductivity of the electrode walls are considered and quantities such as velocity distribution, current streamline distribution, volume flow rate, and conversion efficiency are obtained for a range of Hartmann numbers up to M=100. Results show that decreasing the electrical conductivity in a continuous manner from a high value near the walls to a minimum along the duct axis leads to a high velocity region near the duct axis, a result differing from the essential slug flow character found for Hartmann flows of constant conductivity fluids at high M. The known one‐dimensional Hartmann flow solutions are found to give excellent agreement with the two‐dimensional results for constant conductivity fluids whenever the product of the duct aspect ratio and the square root of the Hartmann number is greater than about ten.

Longitudinal baffling in Faraday generators

A numerical integration scheme for finite Faraday generators shows that no efficiency gain is accomplished by inserting insulating baffles parallel to the flow along the insulating walls of the generator duct. The computations confirm Shercliff’s analysis but differ from that of Yakhot and Levin.

Isothermal expansion of a two‐phase fluid in a magnetohydrodynamic generator duct

A model for one‐dimensional, zero‐slip, two‐phase flow through a Faraday magnetohydrodynamic generator is developed and used to determine the variation in duct cross section as a function of entrance conditions and load factor for uniform power output and velocity along the duct.