The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP) can be classified into fixed and movable types. In movable electrode structures, springs are typically used to push the ...The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP) can be classified into fixed and movable types. In movable electrode structures, springs are typically used to push the electrodes and the propellant. The effects of spring pressure on the ignition and combustion of propellants have not yet been studied. In this paper, a universal testing machine and an electrochemical workstation were firstly utilized to investigate the compressive mechanical property and conductivity of Hydroxylamine Nitrate(HAN)-ECSP. The maximum pressure at which the propellant undergoes elastic deformation is 65 kPa. When the spring pressure increased from 5.1 k Pa to 20.4 kPa, the propellant resistance decreased from 56.8 Ω to 36.8 Ω.Various observation methods were employed to study the process of electrical energy injection and the ignition and combustion characteristics under constant voltage. Appropriately increasing the spring pressure can accelerate the injection of electrical energy into the propellant, increase the electrification current, and thus reduce the initial ignition delay time of the propellant. When the spring pressure is 20.4 kPa, the squeezing speed of the propellant is too fast, making it difficult for the propellant to be adequately heated at the electrode interface, which is unfavorable for ignition. Excessive spring pressure also leads to the accumulation of a large amount of combustion residue on the electrode plate, hindering the mixing and diffusion of hot gases during the second ignition process, preventing the gaseous flame of the propellant. When the spring pressure is 5.1 kPa, improving the working voltage can enhance the repeated ignition characteristics of the propellant.展开更多
The loads acting on the sealing elements of balanced mechanical seals are analyzed. When the balance factor approaches the back pressure factor, the spring pressure will become main part of the face pressure. The leak...The loads acting on the sealing elements of balanced mechanical seals are analyzed. When the balance factor approaches the back pressure factor, the spring pressure will become main part of the face pressure. The leakage model of balanced mechanical seals is established on the base of M-B model for rough surface. Several GY-70 type balanced mechanical seals are tested. The influences of the spring pressure both on the leakage rate and on the friction characteristic of balanced mechanical seals are investigated. The research results indicate that as spring pressure increases, both the clear-ance between two end faces and the leakage rate will decrease, and the friction will be more serious because lubrication medium between the rotating ring and the stationary ring reduces, though the increase of the spring pressure may not be enough to change the face friction state of mechanical seals. There exists an optimum spring pressure for mechanical seal operation. Under this spring pres-sure, not only leakage rate is small, but also the seal end surfaces have a fine friction characteristic. Under different operating conditions, identical type mechanical seals may possess different spring pressure. Appropriate selection of spring pressure is valuable to realize long-period and small leakage rate operating of balanced mechanical seals.展开更多
Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researche...Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.展开更多
基金supported by the National Natural Science Foundation of China(Nos.T222100,22205258,52302485 and 2024JJ5404).
文摘The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP) can be classified into fixed and movable types. In movable electrode structures, springs are typically used to push the electrodes and the propellant. The effects of spring pressure on the ignition and combustion of propellants have not yet been studied. In this paper, a universal testing machine and an electrochemical workstation were firstly utilized to investigate the compressive mechanical property and conductivity of Hydroxylamine Nitrate(HAN)-ECSP. The maximum pressure at which the propellant undergoes elastic deformation is 65 kPa. When the spring pressure increased from 5.1 k Pa to 20.4 kPa, the propellant resistance decreased from 56.8 Ω to 36.8 Ω.Various observation methods were employed to study the process of electrical energy injection and the ignition and combustion characteristics under constant voltage. Appropriately increasing the spring pressure can accelerate the injection of electrical energy into the propellant, increase the electrification current, and thus reduce the initial ignition delay time of the propellant. When the spring pressure is 20.4 kPa, the squeezing speed of the propellant is too fast, making it difficult for the propellant to be adequately heated at the electrode interface, which is unfavorable for ignition. Excessive spring pressure also leads to the accumulation of a large amount of combustion residue on the electrode plate, hindering the mixing and diffusion of hot gases during the second ignition process, preventing the gaseous flame of the propellant. When the spring pressure is 5.1 kPa, improving the working voltage can enhance the repeated ignition characteristics of the propellant.
基金This project is supported by Provincial Natural Science Foundation of Educa-tion Office of Jiangsu, China (No. 04KJD530090)Innovating Founda-tion for Doctoral Dissertation of Nanjing University of Technology, China (No. BSCX200510).
文摘The loads acting on the sealing elements of balanced mechanical seals are analyzed. When the balance factor approaches the back pressure factor, the spring pressure will become main part of the face pressure. The leakage model of balanced mechanical seals is established on the base of M-B model for rough surface. Several GY-70 type balanced mechanical seals are tested. The influences of the spring pressure both on the leakage rate and on the friction characteristic of balanced mechanical seals are investigated. The research results indicate that as spring pressure increases, both the clear-ance between two end faces and the leakage rate will decrease, and the friction will be more serious because lubrication medium between the rotating ring and the stationary ring reduces, though the increase of the spring pressure may not be enough to change the face friction state of mechanical seals. There exists an optimum spring pressure for mechanical seal operation. Under this spring pres-sure, not only leakage rate is small, but also the seal end surfaces have a fine friction characteristic. Under different operating conditions, identical type mechanical seals may possess different spring pressure. Appropriate selection of spring pressure is valuable to realize long-period and small leakage rate operating of balanced mechanical seals.
基金Supported by the Key Project of the National Natural Science Foundation （50490273）
文摘Based on the geological condition of Zhangxiaolou deep mine in Xuzhou mining area, under 986 m in depth, 20.6-31.6 MPa in maximum horizontal principal stress, and friable and fractured surrounding rock, test researches on partial relieving pressure were completed for the entry with U-steel arched yielding support. The relieving pressure parameters, technology process and results of springing blasting by boreholes and excavating pockets in the two sides of entry were introduced. It is demonstrated that springing will not be shaped under the condition of single borehole arrangement after exploded, the arrangement by a group, it will make borehole bottom form springing in 0.6-0.8 m in diameter, that convergence of two sides and roof to floor have some increments by using springing blasting for reliving pressure. This kind of method for reliving pressure is not suitable to use in the deep mine, and that the convergence of two sides obviously declined by excavating pocket in two sides, it can be still used in the entry with metal support, while maintenance of entry in deep mines is difficult, and can not be supported by bolt or bolt with wire mesh.
