Study on the Non-Steady-State Wear Characteristics and Test of the Flow Passage Components of Deep-Sea Mining Pumps

In the process of conveying coarse-grained minerals, the internal flow-through passage components of mining pumps are subject to wear. The flow of coarse particles in such pumps is complex and changes constantly, making it necessary to study the non-steady-state wear characteristics and test the flow passage components. The evolution of the surface wear rate for the flow passage components during one third of a rotation cycle (120°) of a mining pump impeller with small, design, and large flow rates was analyzed in this study based on a discrete phase model (DPM). The flow that occurs during an entire rotation cycle of the impeller was investigated. The wear test was carried out with a small test pump with the same specific speed as and a similar structure to that of the deep-sea mining pump. The test results were compared with the numerical calculation results of the deep-sea mining pump obtained by using the same numerical calculation method and wear model, and the test wear area was found to be more consistent with the numerical calculation wear area. The results show that the numerical calculation method used in this article can more accurately predict the surface wear of the passage components of the mining pump and provides a suitable method for the prediction of the wear characteristics of the mining pump.

Impact of Cooling with Thermal Barrier Coatings on Flow Passage in a Gas Turbine

Inlet temperature is vital to the thermal efficiency of gas turbines, which is becoming increasingly important in the context of structural changes in power supplies with more intermittent renewable power sources. Blade cooling is a key method for gas turbines to maintain high inlet temperatures whilst also meeting material temperature limits. However, the implementation of blade cooling within a gas turbine—for instance, thermal barrier coatings (TBCs)—might also change its heat transfer characteristics and lead to challenges in calculating its internal temperature and thermal efficiency. Existing studies have mainly focused on the materials and mechanisms of TBCs and the impact of TBCs on turbine blades. However, these analyses are insufficient for measuring the overall impact of TBCs on turbines. In this study, the impact of TBC thickness on the performance of gas turbines is analyzed. An improved mathematical model for turbine flow passage is proposed, considering the impact of cooling with TBCs. This model has the function of analyzing the impact of TBCs on turbine geometry. By changing the TBCs’ thickness from 0.0005 m to 0.0013 m, its effects on turbine flow passage are quantitatively analyzed using the proposed model. The variation rules of the cooling air ratio, turbine inlet mass flow rate, and turbine flow passage structure within the range of 0.0005 m to 0.0013 m of TBC thicknesses are given.

Design and Simulated Analysis of Low Heat Flux Cold Plate for High-power Power Electronics Equipment

The thesis has carried out design and simulated analysis of low flux cold plate for high-power power electronics equipment. First, according to heat distribution and design requirements, two kinds of flow passage for low flux cold plate is designed. Then performance characteristics simulation of different flow passage for cold plate is performed. And the heat dissipation characteristics of two kinds of flow passage can both meet the design requirements. Finally, from the perspective of high temperature, temperature difference, pressure drop and so on, the simulated results are comparative analysis. And it is helpful to the design and optimizing of cold plate for high-power power electronics equipment.

Self-excited air flow passage changing device for periodic pressurization of soft robot

Recently pneumatic-driven soft robots have been widely developed. Usually, the operating principle of this robot is the inflation and deflation of elastic inflatable chambers by air pressure. Some soft robots need rapid and periodic inflation and deflation of their air chambers to generate continuous motion such as progress motion or rotational motion. However, if the soft robot needs to operate far from the air pressure source, long air tubes are required to supply air pressure to its air chambers. As a result, there is a large delay in supplying air pressure to the air chamber, and the motion of the robot slows down. In this paper, we propose a compact device that changes its airflow passages by self-excited motion generated by a supply of continuous airflow. The diameter and the length of the device are 20 and 50 mm, respectively, and can be driven in a small pipe. Our proposed in-pipe mobile robot is connected to the device and can move in a small pipe by dragging the device into it. To apply the device widely to other soft robots, we also discuss a method of adjusting the output pressure and motion frequency.

Experimental Study of Characteristics of Flow Field in Rod Bundle Channel Under Blocking Conditions

The rod bundle fuel is characterized by compact structure and narrow flow passage. The fragments and corrosion products, flowing with the coolant, can cause local blockage accident, threaten the integrity of the fuel cladding. Therefore, it is necessary to use the Particle Image Velocimetry (PIV) to visualize and measure the flow fields downstream of the blockages. The results show that partial blockages will cause flow reversal. In the backflow zone, vortices are generated downstream of the blockage, causing increase in the resistance. The length of backflow zone increases with the increase of the Reynolds number. The wake area formed downstream of the blockage presented periodic changes with the time and the period is about 0.8s. For the blockage of the interior subchannels, in the backflow zone, two rows of asymmetrically distributed vortices, and the vortices interfere with each other and cause squeeze deformation. For the blockage of the side and corner sub-channels, the formed vortices have irregular shape and nonuniformed distribution, and the flow field is more complex and changeable. This is believed to be caused by the high intensity turbulence and the influence of the wall.

Self-Excited Air Flow Passage Changing Device for Periodic Pressurization of Soft Robot

Recently pneumatic-driven soft robots have been widely developed. Usually, the operating principle of this robot is the inflation and deflation of elastic inflatable chambers by air pressure. Some soft robots need rapid and periodic inflation and deflation of their air chambers to generate continuous motion such as progress motion or rotational motion. However, if the soft robot needs to operate far from the air pressure source, long air tubes are required to supply air pressure to its air chambers. As a result, there is a large delay in supplying air pressure to the air chamber, and the motion of the robot slow down. In this paper, we propose a compact device that changes its airflow passages by self-excited motion generated by a supply of continuous airflow. The diameter and the length of the device are 20 and 50 mm, respectively, and can be driven in a small pipe. Our proposed in-pipe mobile robot is connected to the device and can move in a small pipe by dragging the device into it. To apply the device widely to other soft robots, we also discuss a method of adjusting the output pressure and motion frequency.

Modeling of fuel transport in pressure-fed systems with flow passage opening devices

This study presents a numerical model of a pressure-fed system with flow passage opening devices (FPODs) designed for an air vehicle with a high degree of maneuverability. The FPOD is a mechanical device that connects two separate fuel reservoirs and functions as a valve allowing liquid fuel to flow while minimizing the movement of pressurizing gas from upstream fuel tanks into downstream fuel tanks. A reduced-order model for the fuel motion in an annular fuel tank was developed to configure the depth and inclination angle of the free fuel surface on the cross-sectional plane of an annular fuel tank under accelerating conditions during flight. Furthermore, a newly proposed model that reflects the dynamic characteristics of the FPOD is used to determine the fluid type that is transported through the device. A simulation example shows that the full numerical model captures changes of the fuel transport condition over time in a complete pressure-fed system of annular fuel tanks with FPODs subject to acceleration.