Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems res...Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve.It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.展开更多
On February 12,the Anhui ProvincialPeople’s Government made a decisionon the speeding up of the use of foreigncapital.The decision involved the followingseven aspects: 1.To seize the opportunity to reviseideology and...On February 12,the Anhui ProvincialPeople’s Government made a decisionon the speeding up of the use of foreigncapital.The decision involved the followingseven aspects: 1.To seize the opportunity to reviseideology and to open up a new situation formaking use of foreign capital.The decisionurges the various localities to seize the righttime to shift their focus to making good useof their own advantages,and improving thelocal investment climate and the quality ofservice in the light of their actual conditionsso as to absorb more foreign funds.Meanwhile,enterprises must be led to face the marketand to join equal competition so as to pushforward the use of foreign funds to a展开更多
文摘Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve.It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.
文摘On February 12,the Anhui ProvincialPeople’s Government made a decisionon the speeding up of the use of foreigncapital.The decision involved the followingseven aspects: 1.To seize the opportunity to reviseideology and to open up a new situation formaking use of foreign capital.The decisionurges the various localities to seize the righttime to shift their focus to making good useof their own advantages,and improving thelocal investment climate and the quality ofservice in the light of their actual conditionsso as to absorb more foreign funds.Meanwhile,enterprises must be led to face the marketand to join equal competition so as to pushforward the use of foreign funds to a
