HYDRAULIC RESISTANCE OF PIPES WITH UNIFORM CONTINUOUS ROUGHNESS IN THE FORM OF A METRIC THREAD OF VARYING PROFILE AND AN INSERTED TWISTED TAPE

Results of experimental investigations into the hydraulic resistance of pipes with a metric thread of triangular, rectangular, and rounded profi les with an asperity height of 0.25 to 1.25 mm, which is cut inside, in air fl ow and with an inserted twisted tape have been given. The degree of swirling varied in the range from 2.5 to 7. A large data array has been obtained on the hydraulic resistance of pipes with a metric thread of varying profi le and an inserted twisted tape. The infl uence of the Reynolds number Re, the degree of swirling, and the relative roughness height on the hydraulic resistance has been analyzed in the laminar regime of swirling fl ow with macrovortices and in the turbulent regime with macrovortices. Generalized dependences have been obtained for calculating the coeffi cient of hydraulic resistance of pipes with a triangular profi le as a function of the degree of swirling and the relative roughness height at Re = 3000–80,000.
   
Author:  A. V. Zlobin and S. É. Tarasevich
Keywords:  hydraulic resistance, metric thread, roughness, fl ow swirl, twisted tape
Page:  1226