Lv et al. conducted a numerical analysis of the internal flow and pressure pulsation characteristics of a submersible tubular electric pump device. The validity of the numerical simulation was confirmed through physical model testing. Their findings indicate that the impeller of the submersible tubular electric pump is primarily responsible for the inlet pressure pulsation of the impeller. Guo et al. investigated the fluid movement law, energy transfer, and loss mechanism in the impeller of an axial flow pump. They successfully identified the main cause of hydraulic losses in the impeller flow passage. This research provides valuable insights into understanding the flow field structure within the impeller of the axial flow pump. Liu et al. (Liu et al., 2023) studied the flow characteristics and evolution of vorticity force in liquid nitrogen cavitation flow using a two-phase flow model and an improved thermal cavitation model. Their research reveals the internal flow mechanism of fluid machinery and offers theoretical guidance for the design of such machinery. Tian et al. examined the internal flow characteristics of low-head bulb perfusion pumps and analyzed the entropy production of essential components. They discovered that the water entropy production head decreases gradually and then increases, with the ratio of entropy production at the impeller to total entropy production being the largest. Xu et al. presented an adaptive mesh refinement technique for simulating compressible flows. This technique effectively refines the mesh in regions containing shock waves and vortices. Numerical results demonstrate that the proposed technique successfully captures shock waves and vortices, leading to improved solution accuracy.

Hong et al. introduced a two-dimensional vortex model to gain insights into the characteristics of shedding vortices in a blade-divergent passage. They proposed a negative circulation unsteady flow control technique as a means to compensate for the viscous effect. The study revealed that this technique is more efficient than conventional flow control methods in mitigating shedding vortex strength. Xu et al. developed an electro-hydraulic composite drive winch and energy recovery system for mobile cranes. Based on electric construction machinery equipped with high-pressure energy-density electric energy storage units, this system incorporates a control strategy to ensure high torque output even at near-zero speeds. Li et al. presented a flywheel-based boom energy regeneration system for hydraulic excavators (HEs) utilizing load sensing systems. In a typical digging and dumping cycle, the energy-saving rate achieved with this system is approximately 32.7% higher compared to conventional load-sensing systems. This method holds promise for the development of energy-efficient HEs. To enhance the uniformity of water distribution under low pressure conditions, Qureshi et al. introduced the aeration jet method for the design of an aeration impact sprinkler. They also presented the structural details of the aeration impact sprinkler. The study demonstrated the feasibility of this method in reducing the operational pressure of sprinklers and improving water uniformity coefficient. Considering the insufficient accuracy of existing cavitation fault feature identification, (Liang et al., 2023) constructed a cavitation state recognition model. By combining current and vibration signals and leveraging information fusion theory, this model aims to improve the recognition rate of cavitation states and enhance anti-interference performance.

In summary, this Research Topic encompasses a wide range of research articles focused on the optimal design and efficiency improvement of fluid machinery and systems. The published articles delve into various aspects of this field, exploring innovative approaches and methodologies. Notably, there is a growing trend towards integrating advanced technologies such as the Internet of Things (IoT) and next-generation communication technologies to enhance the performance and intelligence of fluid machinery. By highlighting these advancements, this Research Topic aims to enrich people’s understanding of fluid machinery and elevate its application level across diverse fields. The knowledge shared through this Research Topic of articles will contribute to the continuous improvement and evolution of fluid machinery, driving innovation and progress in various industries. Ultimately, the goal is to optimize the performance, efficiency, and intelligence of fluid machinery, enabling its widespread application and benefiting society as a whole.