Evaluation of bulk velocity and temperature for turbulent flow in tubes

Abstract

This article describes two methods by which bulk velocities and temperatures can be found without resorting to traversing or the use of mixing chambers; in each case by only one local measurement at the section considered. Both methods depend on a knowledge of the velocity and temperature profiles at that section; knowledge which is now available for fully established turbulent flow in smooth tubes. 1.(a) Axial method: The velocity or temperature probe is placed at the axis, and the reading multiplied by an appropriate weighting factor.2.(b) ymrmethod: The velocity or temperature probe is placed a distance from the wall at which it reads the mean value directly.Information is presented for finding the bulk velocity and temperature by either method, and their relative merits are discussed.When making temperature measurements in a fluid with a thermocouple it is often convenient to bring the wire out radially from a butt-welded junction, and it is then necessary to establish that no serious conduction error is introduced. Data are presented which allow estimates to be made of temperature errors for a centrally placed junction of various materials and gauges, and for various rates of flow and types of fluid including liquid metals.