Представлені результати експериментальних досліджень роз гінного руху рідини в циліндричній трубі зі стану спокою. За при скореного руху рідини спостерігається затягування ламінарного режиму із його подальшим переходом до турбулентного при мит тєвих числах Re, які на кілька порядків перевищують критичне Re в стаціонарних умовах. Для визначення локальних характеристик нестаціонарного потоку використано термоанемометричну апа ратуру. Як датчики для вимірювання локальної швидкості в трубі був застосований термоанемометричний конічний датчик, а для вимірювання дотичних напружень-датчик, що змонтований врі вень з внутрішньою стінкою труби. Для обробки експерименталь них даних крім усереднення за ансамблем було також проведено додаткове згладжування осередненням в часі за п'яти сусідніми точками. Виявилося, що для отримання більш гладких функцій для шуканої характеристики необхідно мати в ансамблі набага то більше дослідів, особливо в пристінній ділянці. Встановлено, що за прискореного руху рідини зі стану спокою до виникнення тур булентності зберігається рівномірний розподіл швидкостей в пере різі труби і лише в тонкому пристінному шарі спостерігаються градієнти швидкос тей. Різкий перехід в характеристиці дотичного напруження на стінці труби τ 0 за зміни ламінарного режиму тур булентним спостерігається також в характеристиках локальних швидкостей. У момент переходу до турбулентного режиму з'явля ється переломна точка на графіку зміни величини середньої швид кості, а розподіл швидкостей та інтенсивність турбулентності зазнають значних змін в порівнянні зі стаціонарними турбулент ними потоками. Турбулентність генерується в пристінній ділян ці та поширюється до центру перерізу трубопроводу практично з постійною швидкістю. Фронт переходу від ламінарного до тур булентного режиму за неусталеного руху рідини в трубі поширю ється у напрямку центру перерізу майже з постійною швидкістю Ключові слова: циліндрична труба, рух рідини, структура пото ку, генерація турбулентності, термоанемометрична аппаратура

Most production technologies require a uniform flow path of liquid from pressure distribution pipelines. To achieve this goal, it is proposed to introduce polymer additives into the liquid flow or to use converging distribution pipelines with a continuous longitudinal slot in the wall. To reduce the uneven operation of the distribution pipeline during discrete liquid dispensing, it is proposed to use cylindrical output rotary nozzles with a lateral orthogonal entry of the jet into the nozzle. The problem is the lack of methods for accurate hydraulic calculation of the operation of distribution pipelines. Adequate calculation methods are based on differential equations. Finding the exact solution of the differential equation of fluid motion with variable path flow rate for perforated distribution pipelines is urgent, because it still does not exist. The available calculation methods take into account only the right angles of separation of the jets from the flow in the distribution pipeline. These methods are based on the assumption that the coefficient of hydraulic friction and the coefficient of resistance of the outlets are constant along the flow. A calculation method is proposed that takes into account the change in the values of these resistance coefficients along the distribution pipeline. The kinematic and physical characteristics of the flow outside the distribution pipeline are also taken into account. The accuracy of calculating the value of the flow rate of water distributed from the distribution pipeline has been experimentally verified. The error in calculating the water consumption by the method assuming that the values of the resistance coefficients are unchanged along the distribution pipeline reaches 18.75 %. According to the proposed calculation method, this error does not exceed 6.25 %. However, both methods are suitable for the design of pressure distribution pipelines, provided that the jet separation angles are straight. Taking into account the change from 90° to 360° of the angle of separation of the jets from the flow in the distribution pipeline will expand the scope and accuracy of calculation methods.

It was established that in the territory of the Stryi river basin, the natural landscapes are maximally preserved in comparison with other regions of Western Ukraine, but under modern conditions an increase of negative anthropogenic impact on the quality of natural waters is observed. The hydrodynamic barriers or hydrodynamically active areas (HAA) of mountain rivers, characterized by a significant oxygen saturation of the water flow, which activates the processes of biochemical and biological self-purification of surface waters, are important for the efficiency of self-purification processes. In order to verify the results of theoretical and field research, an existing experimental setup was designed and improved. It provided the conditions for modeling the flow of mountain rivers in accordance with the laws of similarity theory and the principles of hydrodynamic modeling. On the basis of the results of field observations in the foothills of rivers, as well as regulatory and design documentation, the limits of the main operating factors were determined, namely the Freud number, flow depth and flow rate, which are decisive in studying the impact of HAA on flow self-cleaning processes. By changing the length of the tray section, the gullies and the waterfall niche of the real hydrodynamically active section were simulated, on which field experiments on the Tyshivnytsia River were conducted. In the studies, measurements were performed at different flow regimes, which simulated different hydrological parameters. In order to analyze the impact of HAA on self-cleaning processes, the flow was visualized using photography. The change in the structure of a stream of natural waters at passage of HAA was established. The high oxygen saturation of the river waters of the Stryi river basin is caused by the influence of HAA, which contribute to the purification of polluted waters from biological pollutants and other man-made pollutants and form the high quality of water resources in the region. A method of modeling and visualization of mountain rivers in the laboratory was developed.

No abstract

Problems: The article considers the study of the influence of cavitation phenomena in hydrodynamically active areas of mountain rivers on the processes of natural self-purification of water. The paper considers the experimental results of determining the change in seasonal indicators of the hydrochemical composition of surface waters in the Stryi river basin. Objective: to determine the impact of hydrodynamically active areas (HAA) of mountain rivers on the processes of natural self-purification and to develop methods of laboratory modeling of these areas to determine the hydrochemical parameters of river waters. Methods of implementation: Research of ecological and hydrochemical factors of chemical composition of natural waters of the Stryi river basin combines basin and landscape-geochemical approaches, which allows to integrate various natural and anthropogenic influences, to identify the most important parameters for their detailed analysis. The combination of these approaches made it possible to improve the method of ecological analysis of the area of ​​the Stryi river basin, which allows to spatially differentiate and hydrochemically integrate the factors of formation of the chemical composition of natural waters. Results: It is stated that microbiological safety of water is a special problem, because even water from underground sources may contain single cells of pathogenic microorganisms, but the main threat is water re-contaminated with microbes in case of leaks in the water supply network. Conclusions: Analysis of the results of studies of the impact of self-cleaning processes in the river Stryi on the quality of water intake in Stryi showed that there are currently no negative effects of river waters of the river Stryi on groundwater deposits. The quality of river water is satisfactory for its use in domestic and drinking water supply and for recreational purposes.