Process valves are responsible for regulating and controlling the rate and direction of flow in pipeline systems. The V-port ball valve is one kind of process valve with a regulating performance influenced by V-angle. In this article, a DN50 V-port ball valve is taken as the research object. This work therefore aims to investigate the effect of and relationship between the V-angle on valve performance and internal flow properties via experiments and numerical simulations. Results indicate that an increase in either V-angle or valve opening causes a large-pressure fluctuation near the valve outlet, thus leading to a long pressure-stable distance. Meanwhile, the flow coefficient increases exponentially with valve opening, and the value of the exponent remains at 2.5 for different V-angles. Furthermore, the stable position of internal energy loss along the downstream pipe is well-matched with the stable position of external pressure fluctuation. This inspires a new method for controlling the pressure stability downstream from the valve. These results may facilitate improvements in the design and optimization of the process valve, thus benefiting the development of fluid transport techniques in energy industries.

Axial flow pumps possess a unique structure where there must be clearances between the impeller and the piping wall, usually not exceeding 0.1% of the impeller diameter. Despite the small size of the clearance, the internal micro-vortex structures have a non-negligible impact on the main flow field of the impeller. Under the action of the pressure difference between the suction and pressure surfaces of blades, some fluids form high-energy jets in the tip clearance area, known as tip leakage vortices (TLVs). TLV interacts with the flow of the main flow field, exerting a significant impact on the internal flow state, energy loss, and hydraulic performance of the pump. To identify the influence of TLVs on the internal flow field and energy loss of axial flow pumps, this work uses a modified partially averaged Navier–Stokes (PANS) model to perform full flow field numerical calculations for a certain axial flow pump and conducts a comparative analysis of the internal flow field energy dissipation, unsteady vortex structures, energy loss, and other characteristics under three different tip clearances: 0.2 mm (0.05%D), 0.6 mm (0.15%D), and 1.0 mm (0.25%D) based on the energy transport theory. The results indicate that at optimal operating conditions, the internal energy distribution of the fluid in each flow passage is uniform, and the energy loss is primarily caused by axial backflow in the tip area; under critical rotating stall conditions, clearance size affects the distribution state of enstrophy in the guide vane flow passage, leading to average enstrophy being highest at the rim area and the most uneven distribution of enstrophy, inducing larger energy loss in the impeller; during deep stall conditions, the unevenness of internal energy distribution is stronger than that under critical stall conditions, but the overall energy loss within the impeller flow area is lower than that under critical stall conditions, while energy unevenness is mitigated as the tip clearance size increases.

Fine and large particles flowing through a bend in a pipe move differently and therefore erode the pipe differently. This paper simulates solid–liquid two-phase flow containing large particles in a bend and analyses the relationship between the wear formation and particle motion. Wear experiments are carried out using 3-mm glass bead particles at a mass concentration of 1–15%. At the same time, the flow field and the motion of the granular system are obtained in computational fluid dynamics–discrete element method simulation. The wear formation mechanism is revealed by comparing experiments with numerical simulations. The wear rate of the wall surface increases with the mass concentration, while the marginal growth rate decreases as the mass concentration increases. As the mass concentration increases to a certain value, the degree of wear reaches a maximum and remains unchanged subsequently because of the formation of a particle barrier along the bend wall. The particles near the wall region will bounce forward because of the periodic disturbance flow around particles. The impact of mass bouncing particles causes the formation of the erosion ripple on the test sheet.

Centrifugal pumps, which are essential for the transfer of fluids, are extensively utilized in industries like aerospace and new energy vehicles. These fields require pumps to meet rigorous standards in terms of reliability, efficiency, and vibrational noise while also imposing stringent restrictions on their size and weight. Therefore, achieving optimal performance in terms of both efficiency and noise reduction for centrifugal pumps in limited space poses a considerable difficulty. This study investigates the impact of different volute area ratios on the internal flow properties and noise levels of centrifugal pumps, using area ratio theory as a foundation. Both experimental and computational simulations are used, with the pump dimensions kept constant. The results demonstrate that an augmentation in the volute area ratio greatly improves the pump's exterior properties, notably decreases internal vorticity, and boosts flow conditions. The pressure fluctuations in the pumps show an overall decrease, accompanied by changes in their distribution patterns. In addition, the sound pressure levels in the exterior sound field of the pumps typically decrease, accompanied by obvious changes in directivity. The sound pressure levels within the internal sound field are significantly reduced, especially in areas of the volute wall that were previously known for having high sound pressure. By analyzing the relationship between sound pressure and pressure pulsation on the wall surface of the volute, as well as the impact of area ratio on pressure pulsation distribution in the sound field of the centrifugal pump, it is evident that the theory of area ratio can be utilized to effectively decrease pressure pulsation in the centrifugal pump, thereby reducing the noise generated by the pump.