Hydraulic transportation of the piped carriage is a new energy-saving and environmentally-friendly transportation mode. There are two main states in the conveying process, stationary and moving. In the process of hydraulic transportation of the piped carriage, the study of the stress of the water flow act on the cylinder wall of the piped carriage can help to improve the design of the piped carriage structure and even the selection of piped carriage materials. The distribution of flow velocity around the stationary piped carriage and the stress distribution on the cylinder wall of the stationary piped carriage were investigated by combining numerical simulations with model experiment verification. The commercial finite element software, Comsol Multiphysics, was utilized to solve this problem using the arbitrary Lagrangian–Eulerian (ALE) method. The results showed that the simulation results were in good agreement with the experimental results. It also showed that the ALE method can well be applied for fluid-structure problems in the process of hydraulic transportation of the piped carriage. The simulation results showed that the low velocity region near the inner wall of the pipe was smaller than that near the outer wall of the piped carriage, and both regions decreased with the increase of the discharge. The maximum stress on the cylinder wall of the piped carriage appeared between the two support feet in the middle and rear sections of the cylinder. The influence of the unit discharge on wall stress increased with the increase of the discharge, that is, k₁ < k₂ < k₃. Moreover, the increase of the discharge had the greatest influence on the circumferential component of the principal stress of the cylinder, followed by the axis component, and the smallest influence on the wall shear stress of the cylinder, i.e., ${\overline{k}}_{{\sigma }_c}$ > ${\overline{k}}_{{\sigma }_a}$ > ${\overline{k}}_{{\sigma }_r}$ > ${\overline{k}}_{{\tau }_c}$ .

To enhance the efficiency of irrigation water utilisation, China is progressively converting irrigation ditches into pipelines. The water distribution outlets in irrigation zones are predominantly right-angled, and there are typically occurrences of erosion, sedimentation, and structural deterioration in the surrounding areas. This article employs a synthesis of indoor physical model experiments and theoretical analysis to examine the distribution of channel flow velocity and variations in water surface profile, pipeline flow rate, diversion ratio, circulation intensity, and turbulence energy across different relative water depths. The experimental results indicate that the water surface adjacent to the main canal wall demonstrates a pattern of initial decline, followed by an increase and subsequently another decline; furthermore, as the water level in the main channel rises, the magnitude of this fluctuation progressively diminishes. In some sections of the canal, the water surface elevation progressively increases, albeit with minimal amplitude. With a constant relative water depth, an increase in main channel flow results in a corresponding increase in pipeline flow; however, the diversion ratio is inversely related to the main channel flow. Conversely, when the main channel flow rate is constant, the diversion ratio increases as relative water depth rises. The vertical flow velocity near the water diversion outlet has a negative value, signifying the existence of a backflow zone, while the horizontal flow velocity varies considerably, facilitating the formation of circulation and resulting in localised deposition and erosion. The water flow near the pipe inlet downstream of the lower lip of 0.5 times the pipe diameter is impacted by the return zone, which has a higher turbulence energy and circulation strength and is more susceptible to siltation. The turbulence energy of the water flow is higher in the range of 0.5 times the pipe diameter upstream and downstream of the pipe inlet. This research is highly significant in facilitating the conversion of irrigation channels into pipelines.

Modern irrigation areas often use a combination of channels and pipes for irrigation. Due to changes in terrain, inflow, and pipe diameter, pipelines are often prone to experiencing a state of no pressure. This lack of pressure affects not only the velocity distribution and water surface profile of the main channel but also the velocity distribution and flow distribution of the pipeline. Therefore, in this study, we employed a combination of physical model experiments and theoretical analysis to study the influence of non-pressure pipelines on the hydraulic characteristics of channel–pipe combined irrigation systems filled to different degrees. Through this, the variation laws of the flow velocity distribution, turbulence intensity, water surface, diversion width, and diversion ratio under different filling degrees were obtained. The non-pressure pipeline flow velocity expression was obtained through dimensional analysis, and the calculation formula for the non-pressure pipeline flow velocity coefficient was fitted using linear regression analysis. The relative error between the calculated value and the measured value did not exceed 8.81%. The research results presented in this article can provide technical support for the design and maintenance of channel–pipe combined irrigation systems.

The plate flowmeter offers a novel method for water flow measurement in small channels. Characterized by its simple construction, absence of siltation, and consistent relationship between the deflection angle and flow rate, this device possesses significant potential. Our study, employing rigorous experimental techniques, validated that the gate-hole outflow calculation model is effectively applicable to this plate flowmeter. Additionally, our research investigated the device’s impact on flow velocity distribution. Our findings reveal that the plate flowmeter can be effectively combined with the sluice gate outflow model. It has been verified that the maximum relative error is 14.57%, the minimum relative error is 0.35%, and most relative errors are below 10%. Both water level and flow rate contribute to the flat plate device’s relative head loss, with water level exerting a more significant effect. At various points along the channel, the plate flowmeter affects flow velocity distribution differently. Upstream, the device minimally impacts vertical flow velocity distribution, resulting in steady velocity changes. Conversely, downstream, the flat plate flow meter significantly alters flow velocity distribution, prompting redistribution that persists until 1.26 m downstream, where device influence ceases. These insights offer a solid theoretical foundation for enhancing the structural design of the plate flowmeter, thus improving its overall performance and efficacy.

In the design process for a two-pipe vehicles transportation system, some simple mathematical models are required to quickly calculate the main characteristics of the system. For this purpose, an easy-to-handle mathematical model for the concentric annular gap flow is proposed, and the velocity expression for the concentric annular gap flow is solved using cylindrical coordinates. According to the force characteristics of the two-pipe vehicles, a mathematical model of the two-pipe vehicle motion is established, and the motion and force balance equations of the two-pipe vehicles are deduced. The experimental results are in good agreement with the model results. The factors affecting the two-pipe vehicles movement speed are analyzed, and the standard regression coefficient method in multiple regression analysis is used to determine the influence degree of each factor on the movement speed of the two-pipe vehicles. The research presented in this paper not only enriches the annular gap flow theory, but also provides a theoretical reference for the development of the two-pipe vehicles transportation technology and provides technical support for the realization of relevant industrial applications.