Unsteady cavitating flow with high Reynolds number and significant instability commonly exists in fluid machinery and engineering system. The high-resolution approaches, such as direct numerical simulation and large eddy simulation, are not practical for engineering issues due to the significant cost in the computational resource. The objective of this paper is to provide the approach with Detached-Eddy Simulation (DES) model based on the Reynolds-averaged Navier–Stokes (RANS) equations for predicting unsteady cavitating flows. The credibility of the approach is validated by a set of numerical examples of its application: the unsteady cavitating flows around the two-dimensional (2D) Clark-Y hydrofoil and the three-dimensional (3D) blunt body. It is found that the calculated cavity shapes, cavity lengths and unsteady characteristics by DES model agree well with the experimental measurements and observations. Further analysis indicates that the turbulent eddy viscosity around the cavity and wake region is well predicted by the DES model, which results in the development of large-scale vortexes, and further cavitation instability. The DES model, which exhibits a significantly unsteady 3D behavior, is a more comprehensive turbulence model for unsteady cavitating flows.
The household items delivery robot is a multi-functional robot mainly facing the delivery and handling of household goods. It can handle a variety of items while delivering them, such as cup cleaning and fruit cutting. It achieves the grabbing and delivery of various items through multi-degree of freedom robotic arms and claw-changing devices. Its versatile internal structure enables clean cups, cut fruit and transport items. The multi-functional robot as mainly household goods delivery service will make people living feeling standards having a greater improvement and bring great convenience to home living.
Pet dogs are good friends in people’s home living. Some people sometimes are inconvenient to take care of pet dogs. A smart robot for caring pets is designed in this paper. The robot can actively interact with the pet dog in the way of serve and relieve the separation anxiety of the pet. During the serve process, the multi-stage gears and rack meshing transmissions are used to achieve near, medium and long-range launch modes with stable convenience performance. The structure of this companion pet robot is displayed. It is mainly composed of feeding system, serve system, grasp system, driving system and real-time monitoring system. It is demonstrated here with the feasibility of the machine function and the rationality of the structure design is analysed. The robot will support a good convenience help to pet caring in home living.
In order to realize the automation and integration of wearing and taking off shoes and socks, a service robot for wearing and taking off footwear was designed to help persons living with waist or leg problems in this paper. Through the analysis of the process of wearing and taking off shoes and socks, the robot could carry out this work automatic. The robot mainly consists of intelligent identification system, device for wearing and removing shoes or socks, mobile mechanical arm and power drive with control system. In addition, an auxiliary foot lifting device is designed to cooperate with the service robot for wearing and taking off footwear. The virtual motion simulation of the machine is carried out, and the feasibility of the machine function and the rationality of the structure design are analyzed here.
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