Solid rocket motors have important applications in the propulsion of trans-media vehicles and underwater launched rockets.In this paper,the ignition start-up process of an underwater solid rocket motor across a wide d...Solid rocket motors have important applications in the propulsion of trans-media vehicles and underwater launched rockets.In this paper,the ignition start-up process of an underwater solid rocket motor across a wide depth range has been numerically studied.A novel multi-domain integrated model has been developed by combining the solid propellant ignition and combustion model with the volume of fluid multiphase model.This integrated model enables the coupled simulation of the propellant combustion and gas flow inside the motor,along with the gas jet evolution in the external water environment.The detailed flow field developments in the combustion chamber,nozzle,and wake field are carefully analyzed.The variation rules of the internal ballistics and thrust performance are also obtained.The effects of environmental medium and operating depth on the ignition start-up process are systematically discussed.The results show that the influence of the operating environment on the internal ballistic characteristics is primarily reflected in the initial period after the nozzle closure opens.The development of the gas jet in water lags significantly compared with that in air.As the water depth increases,the ignition delay time of the motor is shortened,and the morphology evolution of the gas jet is significantly compressed and accelerated.Furthermore,the necking and bulging of the jet boundary near the nozzle outlet and the consequent shock oscillations are intensified,resulting in stronger fluctuations in the wake pressure field and motor thrust.展开更多
A differential structure magnetic sensor is proposed.It is comprised of two new-type silicon magnetic sensitivity transistors(SMSTs)with similar characteristics and has a common emitter,two bases and two collectors.Th...A differential structure magnetic sensor is proposed.It is comprised of two new-type silicon magnetic sensitivity transistors(SMSTs)with similar characteristics and has a common emitter,two bases and two collectors.The sensor is fabricated by micro electromechanical system technology on a<100>high resistivity silicon wafer.At room temperature,when supply voltage VDD=10.0 V,all the base currents Ib1 of SMST1 and Ib2 of SMST2 equal 6.0 mA,the absolute magnetic sensitivity for the two SMSTs are 46.8 mV/kG and 56.1 mV/kG,respectively,and the absolute magnetic sensitivity for the sensor is 102.9 mV/kG.Meanwhile,the temperature coefficientαV of the collector output voltage of the sensor is 0.044%/℃.The experimental results show that the magnetic sensitivity and the temperature characteristics of the sensor can be improved and ameliorated compared with a single SMST.展开更多
High performance polymers have received considerable attention over the past decade owing to their increased demands as replacements for metals or ceramics in automotive, aerospace, and microelectronic industries. Pol...High performance polymers have received considerable attention over the past decade owing to their increased demands as replacements for metals or ceramics in automotive, aerospace, and microelectronic industries. Poly（aryl ether ketone）s（PAEKs） are a class of important high-performance aromatic polymers with excellent mechanical properties, good solvent resistance, size-accuracy, electrical characteristics, and superior thermal stability. However,展开更多
基金supported by the National Level Project of China.
文摘Solid rocket motors have important applications in the propulsion of trans-media vehicles and underwater launched rockets.In this paper,the ignition start-up process of an underwater solid rocket motor across a wide depth range has been numerically studied.A novel multi-domain integrated model has been developed by combining the solid propellant ignition and combustion model with the volume of fluid multiphase model.This integrated model enables the coupled simulation of the propellant combustion and gas flow inside the motor,along with the gas jet evolution in the external water environment.The detailed flow field developments in the combustion chamber,nozzle,and wake field are carefully analyzed.The variation rules of the internal ballistics and thrust performance are also obtained.The effects of environmental medium and operating depth on the ignition start-up process are systematically discussed.The results show that the influence of the operating environment on the internal ballistic characteristics is primarily reflected in the initial period after the nozzle closure opens.The development of the gas jet in water lags significantly compared with that in air.As the water depth increases,the ignition delay time of the motor is shortened,and the morphology evolution of the gas jet is significantly compressed and accelerated.Furthermore,the necking and bulging of the jet boundary near the nozzle outlet and the consequent shock oscillations are intensified,resulting in stronger fluctuations in the wake pressure field and motor thrust.
基金Supported by the National Natural Science Foundation of China under Grant No 61006057the China Postdoctoral Science Foundation of China under Grant No 2013M530163+1 种基金the Heilongjiang Postdoctoral Science Foundation under Grant No LBHZ12225the Modern Sensor Technology Innovation Team for College of Heilongjiang Province under Grant No 2012TD007.
文摘A differential structure magnetic sensor is proposed.It is comprised of two new-type silicon magnetic sensitivity transistors(SMSTs)with similar characteristics and has a common emitter,two bases and two collectors.The sensor is fabricated by micro electromechanical system technology on a<100>high resistivity silicon wafer.At room temperature,when supply voltage VDD=10.0 V,all the base currents Ib1 of SMST1 and Ib2 of SMST2 equal 6.0 mA,the absolute magnetic sensitivity for the two SMSTs are 46.8 mV/kG and 56.1 mV/kG,respectively,and the absolute magnetic sensitivity for the sensor is 102.9 mV/kG.Meanwhile,the temperature coefficientαV of the collector output voltage of the sensor is 0.044%/℃.The experimental results show that the magnetic sensitivity and the temperature characteristics of the sensor can be improved and ameliorated compared with a single SMST.
基金Supported by the National High Technology Research and Development Program of China(No.2006AA03Z543).
文摘High performance polymers have received considerable attention over the past decade owing to their increased demands as replacements for metals or ceramics in automotive, aerospace, and microelectronic industries. Poly（aryl ether ketone）s（PAEKs） are a class of important high-performance aromatic polymers with excellent mechanical properties, good solvent resistance, size-accuracy, electrical characteristics, and superior thermal stability. However,
