Advanced Materials Research Vols. 562-564

Abstract: The low altitude breakthrough has become an important battle mode of modern war, which brings the huge difficulty for low altitude defense. The microwave technology is an effective method to detect the moving target in the low altitude. Taking the frequency modulation of microwave as basic principle, and combined the Doppler Effect which can measure the velocity information of target, a microwave detecting system based on twice mixing is established. Its composition and working principle are analyzed, and the circuits are designed. The laboratory experiment indicates that it is completely feasible to apply the system to the detection of the moving target.

Abstract: In the pan or platform carrier supply system, the intake pipe structure of the generator is very important for stability and efficiency of the airflow vibration-driving work in the small-hole aerodynamic piezoelectricity generator. Hyperbolic curved nozzle produces higher jet velocity than straight-wall nozzle. Using CFD method, contrast and analyse the annular identical-cross-section straight pipe and annular hyperbolically curved pipe, the calculation results prove the superiority of the hyperbolically curved pipe. For the geometry characteristic of the annular hyperbolic curved pipe structure, influence on the velocity distribution through varying parameters of the structure size was found out. The results show that development of the velocity distribution is directly affected by the length of straight pipe section of the pipe; better velocity distribution is obtained when length of straight pipe increases properly. On the other hand, a smaller ratio of aperture ring gap has a significant contribution to the out airflow velocity distribution.

Abstract: In order to study the effect of hot EGR on combustion characteristic of hydrogen internal combustion engine (HICE), experimental study was taken on a 4 cylinder, 2.0L HICE. The speed was 3000rpm, and the throttle was fully open, the load was adjusted through quality regulation. When the hydrogen flow ratio was 2.79kg /h, the ignition advanced angle was optimized as maximum brake torque (MBT) timing, then the EGR valve was opened, and EGR valve was adjusted to control the flow of exhaust gas that back into the intake manifold. The test results show that: as the EGR ratio changing from 0(the EGR valve is fully closed) to 43.8%(the EGR valve is fully opened), the in-cylinder pressure is decreasing with the EGR ratio increasing; the coefficient of variation in indicated mean effective pressure (imepCOV) is not changing significantly at high load conditions, changing range is less than 1%; CA50 is postponed from 11.8oCAto15.2 oCA with EGR ratio increasing.

Abstract: The analysis process for the linear coupled vibration of a circular container and its inner liquid often uses FEM method. An equation set which contained the fluid node pressure and the structure node displacement was formed, based on these equations, in this paper, a new equation set which has a smaller dimension and symmetrical form is obtained by the method of model reduction and coordinate symmetrization. By solving the boundary value problems of equivalent Laplace formulas, the additional masses matrix, additional stiffness matrix and coupling matrix which have effect from fluid to structure are gained. The example of the modal analysis for liquid container demonstrates that this method presented in this paper can get the modal frequency accurately and rapidly in fluid-structure coupled vibration system and other similar engineering realm.

Abstract: Based on the heat and mass transfer theory and characteristics of the FLUENT software, a three-dimensional numerical simulation platform composed by user defined functions had been developed to simulate the thermal performance in a natural draft wet cooling tower. This platform was used to study a typical hyperbolic natural draft wet cooling tower with different fill types. The variations of the flow and temperature field in the cooling tower caused by the two different methods of fill were investigated. It is found that the outlet water temperature will decrease due to the non-uniform fill depth. The non-uniform fill depth is beneficial to increasing the efficiency of the cooling tower.

Abstract: By means of GT-POWER code, the simulation model of diesel has been established whose cylinder pressure was calibrated. The simulation and experimental result accorded mostly which validated the correctness of this model. The MAP of the heat release rate was obtained basically. The results showed that at low load, the higher the speed is, the larger the heat release rate is; on the condition of the high load, with the increase of the speed, the heat release rate decreases firstly and increases afterwards. This study could offer a guidance to the designment of the coolant system.

Abstract: Being one of the key parts in high-speed traction motor ,rotor shaft has a great influence on the dynamic characteristics of high-speed traction motor. This paper uses the UG to establish a simplified model of high-speed traction motor rotor shaft. The modal parameters were calculated and its inherent frequency characteristics were investigated with the analysis software MSC.Nastran. And we also analyze and calculate the foregoing five model shape of high-speed traction motor rotor shaft. These can provide a basis for the optimization design of high-speed traction motor rotor shaft and its dynamics analysis.

Abstract: To reduce the HC emissions of a CNG engine during starting period, starting experiments were carried out on a CNG engine. Injection pulse width (IPW) and spark advance angle () were controlled. The results indicate that wider injection pulse width and earlier spark timing cause higher HC emissions. To guarantee a reliable start and low HC emissions, the engine should start with relatively wider injection pulse width and earlier spark timing, and the injection pulse width and spark advance angle should be reduced gradually after the engine speed is steady.

Abstract: Variations in high pressure common rail (HPCR) system characteristic parameters influence injection characteristics and lead to fluctuation of fuel injection quantity (FIQ). The fuel injection quantity fluctuation (FIQF) has adverse affects both on coherence and stability of HPCR system. Numerical simulation model of HPCR has been developed and its accuracy has been validated by experimental results. Influence law and generation mechanism of FIQF caused by variations of different parameters such as fuel return pressure, solenoid reset force, control valve lift, fuel return orifice (A orifice) diameter, fuel inlet orifice (Z orifice) diameter, injector needle lift, needle pre-tightening force and injector flow coefficient in entire operating conditions have been analyzed.

Abstract: Based on the BOSCH injector for research object, driving circuit is adopted the "dual voltage" adjustable pulse width driven model. Using the method of combining simulation analysis and correlation calculation, the key parameters in the boost circuit and the logical drive circuit is studied and selected. Experimental results show that the driver modules meet the needs of high speed solenoid, basically achieved the target.