EXPERIMENTAL INVESTIGATION OF FLOW DISCHARGE IN A SEMI-CIRCULAR STEEL PIPE CHANNEL

ABSTRACT

This study focuses on the investigation of hydraulic processes in a semi-circular steel pipe channel. A steel pipe that had been in operation for 30 years was used as the test channel, with an internal diameter of 165 mm and a length of 2 m. Average flow velocity was measured using a GMCM-1 micrometer, and discharge was determined by both velocity-area and mass methods. The comparison of these methods revealed a deviation of about 3%. The results demonstrate that the velocity-area method provides reliable estimates of flow discharge in semicircular steel pipe channels under turbulent flow conditions.

This study focuses on the investigation of hydraulic processes in a semi-circular steel pipe channel. A steel pipe that had been in operation for 30 years was used as the channel, with an internal diameter of 165 mm and a length of 2 m. The average velocity of the fluid flow was measured using a GMCM-1 micrometer. When the fluid depth was 28 mm, the fluid flow rate was determined using the velocity-area method. The results determined by the velocity-area method and the mass method were compared.

АННОТАЦИЯ

В данной работе изучаются гидравлические процессы в канале, выполненном из полукруглой стальной трубы. В качестве канала использовалась стальная труба, находившаяся в эксплуатации 30 лет, с внутренним диаметром 165 мм и длиной 2 м. Средняя скорость потока измерялась микрометром ГМЦМ-1, а расход определялся методами «скорость-площадь» и масс. Сравнение этих методов показало отклонение около 3%. Результаты показывают, что метод «скорость-площадь» обеспечивает достоверные оценки расхода потока в полукруглых стальных трубах при турбулентном течении.

В данной научно-исследовательской работе исследовались гидравлические процессы в канале, выполненном из полукруглой стальной трубы. В качестве канала использовалась стальная труба, находившаяся в эксплуатации 30 лет, внутренним диаметром 165 мм и длиной 2 м. Средняя скорость потока жидкости измерялась микрометром ГМЦМ-1. При глубине жидкости 28 мм расход жидкости определялся методом «скорость-площадь». Сравнивались результаты, полученные методом «скорость-площадь» и методом масс.

Keywords: steel pipe, semi-circular channel, velocity distribution, discharge estimation, mass-based method, turbulent flow.

Ключевые слова: стальная труба, полукруглый канал, распределение скорости, оценка расхода, массовый метод, турбулентное течение.

1. Introduction.

The study of hydraulic processes in a semicircular channel is currently of great practical and theoretical importance. Although hydraulic processes in trapezoidal channels have been studied in many cases, processes in semicircular channels have been studied relatively less. In addition, one of the important tasks is to study the channel roughness and hydraulic processes in a steel pipe that has been operated for a certain period of time. There is a need to determine several parameters of hydraulic processes, including the average velocity and velocity distribution in the channel, through experiments. [1, 4, 9].

Determining fluid flow rate is a key objective in experimental and engineering projects. In most cases, flow rate is determined using velocity-area methods, but in laboratory conditions, determining flow rate by mass method helps us to obtain more accurate results.

Accurate measurement of flow discharge is one of the fundamental requirements in both laboratory research and engineering design. Typically, flow discharge is measured either through velocity-based methods or by mass (gravimetric) methods. Velocity-based approaches, such as those using propeller-type current meters, ultrasonic sensors, or electromagnetic devices, rely on point velocity measurements that are integrated across the cross-sectional area. In contrast, mass-based methods directly measure the outflow volume or weight over time and are considered a reference standard[2, 12, 19].

However, sometimes differences between the above methods may occur due to changes in the velocity profile, turbulent motion, and measurement accuracy of the devices. Therefore, conducting experimental studies to determine the reliability of the velocity-surface method in such channels is an important task [1-5, 16-19].

The present study investigates the discharge characteristics of water flow through a semi-circular steel pipe channel under laboratory conditions. Using the  micro-propeller device, velocities were measured at three cross-sections along the channel. From these velocity measurements, discharges were calculated and compared with mass-based discharge measurements. The comparison provides insight into the accuracy of velocity-based methods in turbulent flow conditions[3, 6, 7].

2. Materials and methods.

Experimental studies were conducted in the laboratory of the National Research University "Tashkent Institute of Irrigation and Agricultural Mechanization Engineers". A semicircular steel pipe with a length of 2 m and an internal diameter of 165 mm was selected as the research object. This pipe was used as a channel. 3 sections were separated in the channel. The average velocity of the liquid along the verticals in each section was measured using a microrotor, ensuring smooth movement. The liquid consumption was determined by the velocity-area and mass methods. In this case, the liquid depth was 28 mm.The experimental setup consisted of a semi-circular steel pipe channel with a total length of 2.0 m and an internal diameter (channel width) of 165 mm. The flow depth was maintained at 28 mm.

3. Results and discussion

The fluid consumption determined by the mass method was determined by the following expression

When the fluid depth was 28 mm, the Reynolds number was approximately 18,500.

The average fluid velocities along the verticals in the selected sections were measured using a microrotor. The results are shown in the figure below.

Figure 1. Average fluid velocity in sections. a) Section 1-1 b) Section 2-2 c) Section 3-3

The fluid consumption determined by velocity-surface was as follows:

Table 1.

The fluid consumption determined by velocity-surface

4. Conclusion

The results indicate that when a semicircular steel pipe is used as a channel, the liquid depth is h=28 mm Re=18500. Compared with the liquid flow determined by the mass method, the error in the liquid flow determined by the velocity-area method is 3-3.1%. From this, it can be concluded that the velocity-area method can be considered reliable to determine the fluid flow in small and large channels.

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