Study Of Multi-hydraulic Butterfly Valve On-off Control Hydraulic System Of A Ship

The on-off control hydraulic system of Multi-hydraulic butterfly valve is the important equipment for many kinds of ships. Based on the on-off control to the hydraulic butterfly valves by using the hydraulic actuators, the function of opening and cutting the channel can be achieved. the goal to allocate the ballast water, the daily fuel and the fire water and the other fluid medium in the pipe reasonably is achieved at last, thus can provide security for the posture balance of the ship, the normal running of equipment and the fire safety. Because the hydraulic system used to control the butterfly valves has the feature as relatively simple functions, low reliability and security, and lack of deep theoretical analysis, therefore, it's necessary to study on the Multi-hydraulic butterfly valve on-off control hydraulic system and resolve the key technologies involved in the design process, finally the goal of providing reliable theory and design basis for the design of the hydraulic butterfly valves on-off control hydraulic system used in other ships can be achieved.According to the features as a large number of hydraulic butterfly valves on ship and long hydraulic pipes, etc, a Multi-hydraulic butterfly valve on-off control hydraulic system based on the water-based fire retardant hydraulic fluid has been designed in this paper, and the test platform has also been built. During the design process of the system, the redundancy design method is used, we use two hydraulic power units to control parts of hydraulic butterfly valves separately, an flow limiting cut-off valve is set at the drain port of each hydraulic power unit, through the coupling control of the electromagnetic valve box, the interactive control problem of each hydraulic butterfly valve in emergency situation is solved.An accurate calculation method for the pressure loss of the long pipe is proposed. On the basis of full consideration of the relationship among frictional heat, the heat loss of the pipe wall and the fluid energy, the heat balance equation and Bernoulli equation etc. are used to model the pressure loss of the long hydraulic pipe; and in the condition of multiple ambient and tank temperatures, a numerical simulation and experimental verification have been done for the above model. This calculation method has important practical value in the design and performance analysis of the hydraulic system.Based on the hydraulic system, the following simulation and experimental research have been done, such as the variation rule of the rotational angular velocity and its error, the on-off time as well as the influential factors for each hydraulic butterfly valve when thay are in the switching process. The results show that the variation rule of the rotational angular velocity is associated with load characteristics; and the error of its rotation velocity and the on-off time are affected greatly by the ambient and tank temperatures. The above simulation method and results can provide theoretical and experimental bases for the establishment of the switching control strategies for each hydraulic butterfly valve.Usually, the hydraulic actuators and the hydraulic butterfly valves are connected by the long pipes, blowing off the hydraulic fluid in the pipes is involved in the hydraulic system maintenance. According to the gas-liquid two-phase flow and other related theories, the gas-liquid two-phase flow mathematical model is established based on the method of differential time unit, the relationship between the volume blown off from the hydraulic fluid pipe with the blowing pressure and the blowing time is obtained by simulation; and the results of the simulation is verified by experimental study. The result can provide the reference for the maintenance and management of the hydraulic system.