TsAGI Science Journal

ABOUT THE POSSIBILITIES OF EQUIVALENT SAND-GRAIN ROUGHNESS CALCULATION FOR FLOWS IN PIPES AND IN BOUNDARY LAYERS

ABSTRACT

The experimental investigations of frictional drag measurements on surfaces with regular roughness have been performed and the equivalent sand-grain roughness of the investigated surfaces has been obtained. On the basis of Schlichting's classical experimental data and the results of the measurements, a formula allowing a value of the effective sand-grain roughness of a surface to be estimated is offered. The obtained formula is applicable to surfaces consisting of ledges with comparable cross-sectional sizes and close heights. In particular, rough surfaces formed by sputtering can be included in this type of the surface.

REFERENCES

1. Flack, K. A. and Schultz, M. P., Review of hydraulic roughness scales in the fully rough regime.

2. Lashkov, Yu. A., Mikhailov, V. V., Samoilova, N. V, and Uspenskii, A. A., Hydraulic resistance of a pipe with a surface film.

3. Mikhailov, V. V., Refined formula for calculating the hydraulic drag coefficient of a pipeline.

4. Shlichting, H., Boundary Layer Theory.