Dynamic simulation of buoyancy engine of underwater glider based on experimentation
As a key component for underwater gliders, the buoyancy engine plays an important role in the operation of gliders, the performance of which directly affects the monolithic reliability. In this paper, to lower costs of research on the buoyancy engine, a dynamic simulation is established by AMEsim software, in which the performance of the low-pressure boost gear pump and that of the high-pressure hydraulic axial piston pump are analyzed. And based on the simulation results, an experiment is designed to verify validity of the simulation. The method of buoyancy engine simulation in this paper may provide a valuable reference for designers.
Energy recovery and conservation utilizing seawater pressure in the working process of Deep-Argo profiling float
Abstract Argo profiling float is the key equipment of global ocean observation system. Energy supply issues have limited the working time and the exploring depth of Deep-Argo. In this paper, the scheme of energy recovery and conservation utilizing seawater pressure is put forward innovatively. The hydraulic motor is used to recover and conserve energy when seawater drives hydraulic oil moving from buoyancy bladder to storage bladder in the descending process of Deep-Argo. The working environment of Deep-Argo is defined by the data from sea trials and the simulation model based on AMESim-Simulink is verified by the experiment. Several cases are conducted to analyze the effect of energy recovery and conservation. It shows that the larger fluid drag coefficient of Deep-Argo will lead to the smaller motion speed and the larger energy consumption. The input pressure of hydraulic motor is related with its working time and working frequency. Under the condition that Deep-Argo could reach the target depth, the less volume of hydraulic oil driven by hydraulic pump and the higher input pressure of hydraulic motor will lead to better results of energy recovery and conservation. The recovered energy by the hydraulic motor can be 11.35% of the consumed energy by the hydraulic pump and the conserved energy can be 2.77% of the consumed energy by the hydraulic pump. This paper verifies the feasibility of the scheme for energy recovery and conservation utilizing seawater pressure for Deep-Argo profiling float, and provides the basis for further applied research.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.