Author(s): G. V. Vasilchenko
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Keywords: No Keywords
Abstract: The paper describes a method and engineering devices used for measuring velocities in a turbulent boundary layer flow at the rough permeable wall and gives some of the me-asurement results. It contains some details of the principle of the electrochemical me-thod for measuring the velocities, designs of electrochemical velocity meters, specific features of unsteady-state velocity measurements at rough flow boundaries, potentialities of the method and its efficiency. The relevant literature is scanty as yet. Two types of electrochemical meters are known at present. The first type, designed as a plane microelectrode, measures shearing stresses at hydraulically smooth boundaries, and is, therefore, imbedded flush with the boundary surface (Hanratty's method). The se-cond type of the meters is cylindrical sphere-shaped microelectrodes 0.1 to 1.0 mm dia, which serve for direct measurement of unsteady-state velocities at scattered points wi-thin the boundary layers, between roughness elements and in the bulk of the loose mate-rial adjacent to the flow. The paper concerns operation of the meters in unsteady-state flows, estimation of their time-delay, procedures of static and dyamic calibrations. The paper is concluded by a section containing some results of measuring the mainparameters of turbulent flows at rough boundaries.
Year: 1985