Editorial: Design, simulation and optimization of hydraulic machinery

With the increasing pressure of energy crisis and carbon emission, the energy-saving technology of industrial processes has attracted worldwide attention. Hydraulic machinery and its systems are the key components for the sustainable development of engineering, energy transformation in hydraulic systems, water resources, and chemical industry including various transport of liquids or mixtures. The growing demands for the increase of processes operation efficiency have encouraged and indicated the development and implementation of the optimization at the design stages for pumps and pump systems based on mathematical and physical models, advanced numerical simulation, or data-driven techniques.Recently, an increasing number of papers have discussed the design and optimization for the improvement of pumps, turbines, valves, and other flow components. Many new theories and methods have been proposed and applied to improve hydraulic performance. For more efficient utilization of hydraulic machinery, it is important to collect up-to-date information on this topic.