Pressure regulation by known means is carried out only in the direction of its reduction. This paper examines local flow control devices in fluid systems, namely local hydraulic resistances. Under turbulent flow conditions, pressure losses in a sudden pipe contraction primarily occur during flow expansion downstream of the vena contracta, in the vortex region that forms behind the diameter transition plane. For sudden pipe contraction, flow resistance can be reduced by altering the shape of flow boundaries – by influencing the fluid stream, acting on the pipe wall, or modifying the cross-section along the flow direction. The methods discussed for reshaping boundaries can reduce the size of the vortex region behind the pipe contraction. In certain cases, these methods can even eliminate the vortex region entirely. The resulting flow behavior becomes similar to that of a sudden pipe contraction with a higher contraction ratio.
Chernyuk, V. V. (2000). Regulation of pressure in hydraulic and pneumatic systems. Bulletin of Lviv Polytechnic National University: Thermal Engineering. Environment Engineering. Automation, 404, 14–18. (in Ukrainian). https://ena.lpnu.ua/items/84a131bd-7aef-4953-9c69-5d173e6dec30
Chernyuk, V. V. (2010). Regulation of integral parameters of enforced fluid flows by means of hydrodynamic active additives (Doctoral dissertation). Kyiv (in Ukrainian). https://scholar.google.com/scholar?cluster=6411591177049904689&hl=en&oi=...
Idelchik, I. E. (2008). Handbook of hydraulic resistance. New York, Connecticut, Wallingford (U.K.), Begell House, Inc. https://doi.org/10.1615/978-1-56700-251-5.0
Satish, G., Ashok Kumar, K., Vara Prasad, V., & Pasha, Sk. M. (2013). Comparison of flow analysis of a sudden and gradual change of pipe diameter using fluent software. International Journal of Engineering Trends and Technology, 25 (4), 41–45. https://doi.org/10.15623/ijret.2013.0212006
Borysyuk, A. O. (2022). A numerical technique to solve a problem of the fluid motion in a straight planerigid duct with two axisymmetric rectangular constrictions. Reports of the National Academy of Sciences of Ukraine, 1, 48–57. https://doi.org/10.15407/dopovidi2022.01.048
Mollo-Christensen, E. (1971). Physics of Turbulent Flow. AIAA Journal, 9 (7). 1217–1228. https://doi.org/10.2514/3.49933
Orel, V. I. (2003). Influence of the polyacrylamide additives on the pressure losses of sudden narrowings and expansions in pipes (PhD dissertation). Rivne (in Ukrainian). https://ena.lpnu.ua/items/e26036a4-dca6-4a9b-9cbb-9dbea95de5cf/full
Orel, V. I. (2013). Study of the contribution of irreversible losses to total pressure losses at a sudden contraction of the pipe. Problems of Water supply, Sewerage and Hydraulic, 21, 181–190. (in Ukrainian). https://ena.lpnu.ua/items/e1349ed4-1a39-4567-80da-45d20ad47453
Ando, T., & Shakouchi, T. (2004). Flow characteristics over forward facing step and through abrupt contraction pipe and drag reduction. Research Reports Faculty Engineering Mie University, 29, 1–8. https://www.eng.mie-u.ac.jp/research/activities/29/29_1.pdf
González, J., Meana-Fernández, A., Pérez, I. V., & Oro, J. M. F. (2024). Minor Loss Coefficient for Abrupt Section Changes in a Cylindrical Pipe Using a Numerical Approach. Fluids, 9, 152. https://doi.org/10.3390/fluids9070152
Nosko, S. V., & Shevchuk, O. A. (2013). The structure of flow in the complex duct in a radial admission of escapages. Eastern-European Journal of Enterprise Technologies, 2, 7(62), 57–60. (in Russian). https://journals.uran.ua/eejet/article/view/12390
Essel, E. E., & Tachie, M. F. (2017). Upstream roughness and Reynolds number effects on turbulent flow structure over forward facing step. International Journal of Heat and Fluid Flow, 66, 226–242. https://doi.org/10.1016/j.ijheatfluidflow.2015.11.004
Rennels, D. C., & Hudson, H. M. (2012). Pipe Flow. A Practical and Comprehensive Guide. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. https://doi.org/10.1002/9781118275276
Miller, D. S. (1990). Internal flow systems. Cranfield, Bedford, BHRA (Information Services). https://online.fliphtml5.com/izcjx/lpcm/#p=148
Bullen, P. R., Cheeseman, D. J., & Hussain, L. A. (1996). A study of turbulent flow in pipe contractions. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 210 (3), 171-180. https://doi.org/10.1243/PIME_PROC_1996_210_312
Sydor, T., & Orel, V. (2025). Influence of geometric parameters of pipe narrowing on pressure losses in a pressure short pipeline. Problems of Water supply, Sewerage and Hydraulic, (49), 53–60. (in Ukrainian) https://doi.org/10.32347/2524-0021.2025.49.53-60