Abstract: Structure parameters of diesel engine spray system have decisive effects on its performance. The paper studies the effects of 8 sets of nozzles with different structure parameters on performance of diesel engine with the purpose to realize high-efficiency, low-emission and low-noise combustion process in diesel engine, based on requirements and characteristics of performance optimization of DI diesel engine, thus realizing optimum design of nozzle structure parameters for high pressure common rail diesel engine.
Abstract: Ultrasonic motors adopting longitudinal vibration of bar were widely studied for their considerable thrust, high efficiency and reliability. A novel ultrasonic motor using longitudinal vibration of bar with varying section was proposed in this paper. This ultrasonic motor features with two varying section bars connected by semi-circumferential structure. Elliptical trajectories of particles are formed on top of the semi-circumferential structure outer surface where driving foot located and a mover is pushed to move when the driving foot is pressed onto it. FE model of its stator was built and results of harmonic analysis verified its principle. Testing of prototype shows that this motor was capable of a 10N load with speed 100mm/s.
Abstract: In this paper, with the ANSYS, stress distribution, safety factor and fatigue life cycle of high-pressure common rail diesel engine connecting rod were analyzed by using 3D finite element method. The results show that the position of maximum principal stress is transition location of small end and connecting rod shank at maximum compression condition. The value of stress is 253.98 MPa in dangerous position. Safety factor is 2.67. The position of maximum principal stress is medial surface of small end at maximum stretch condition. The value of stress is 87.199 MPa in dangerous position. The fatigue life cycle of connecting rod is 2.6812×108. Fatigue safety factor is 1.5264.
Abstract: The criterions of parameter selection for a tuned frequency muffler are proposed. The experimental results show that the radius of a cylindrical perforated tube dissipative muffler meets the criterions. Based on the conclusion, through installing the rotatable circumferential separate plates, an actuator of the tuned frequency muffler is designed to realize automatic adjustment of the radius, which is available for two kinds of working conditions of acoustic attenuation and can both attain the optimal acoustic attenuation performance. Utilizing the finite element analysis and the experiment test, variation rules of transmission loss versus the muffler’s radius is further investigated. The results show that the variable-radius method used in the tuned frequency muffler can shift the frequency band of acoustic attenuation and optimize the acoustic attenuation performance, which expands the application fields of mufflers and has a great engineering value.
Abstract: In this paper, a phase-divided spray mixing model is proposed and the quasi-dimensional model of diesel engine working process is developed. The software MATLAB/Simulink is utilized to build the quasi-dimensional model of diesel engine working process, and the performance for diesel engine is simulated. The simulation results agree with experimental data quite well which indicates that the simplified quasi-dimensional model has high precision for predicting diesel engine performance. By utilization of this simulation model, the average computational time for one diesel engine working process is 36 s, which presents good real time operating performance of the model. On the basis of the principle of orthogonal test design, the performance of diesel engine was optimized by use of the quasi-dimensional model.
Abstract: For the stiffness of the cutting face is nonuniform, the evenness of the machining face may not be ensured during a gearbox back shell’s cutting process. By reasonably simplifying the machining process, a cutting stiffness contrast analysis of three design schemes is performed in this paper, and then improvement advice is brought forward to the design engineer. The paper has some engineering value and can be used for reference in similar analysis.
Abstract: Using Heavy Fuel Oil (HFO) is a practical measure to reduce running cost of high-speed diesel engines. Extending application of HFO would be great helpful to mitigate nation wide energy shortage problem. The authors attempted a set of experiments with a view to demonstrating the performance of a high-speed diesel engine fuelled with fuel blend of HFO and Light diesel (HFO-L) and water emulsified HFO-L. A number of experiments on test bench were carried out to check power performance, fuel economy and combustion performance of the engine. The results indicate that it is practicable to use HFO-L fuel blend on high-speed diesel engine without many additional modifications on engine structure. Compared with HFO-L, water emulsified HFO-L has better combustion performance, and thus better fuel economy as well as low harmful emissions. In addition, compared with using light diesel fuel, when using emulsified HFO-L blend, the engine can be operated with the same power performance, but with higher the brake specific fuel consumption. Whereas, considering much lower price of heavy fuel oil, the fuel economy is greatly improved.
Abstract: Mixing efficiency is an important parameter in the design of many industrial processes in stirred tanks. In this study, CFD technology was used to simulate the mixing process inside the stirred tank with dislocated blades and standard turbine. Calculations were performed to study the effects of agitator speed and the configuration of impellers on mixing efficiency. The results showed that the flow field in the stirred tank with the dislocated blades is better than the standard turbine, and the flow number of the dislocated blades had been improved while the power number had been reduced. According to calculation results of Wr, we found the mixing efficiency of the dislocated blades had been improved about 4 times than that of standard turbine.
Abstract: This paper primarily focuses on the analysis on the heat exchange part’s flow field of the jet plug-in hot blast furnace, and comprehensively considers the temperature field aiming at obtaining the velocity and pressure distribution of the air and flue gas in each part of the heat transfer. Heat exchange mainly takes advantage of thermal convection about high temperature flue gas of the hot blast furnace and air, the flow situation of which have the direct effects on the heat exchange result in the heat transfer. The authors implemented the numerical simulation on flow field of the jet plug-in hot blast stove in heat transfer by using the method of finite element analysis. The conclusion of this paper provides the basis for the further enhancement of the machine life and optimization of the structure design.
Abstract: In the large fluctuation transition process of hydropower unit, hydraulic turbine operating condition changes drastically, following the change, hydraulic-turbine transfer coefficients also change drastically, thus the mathematical model of hydro-turbine governing system is nonlinear. This paper establishes simulation model of large fluctuation transition process in SIMULINK software, puts forward a method of establishing simulation model of nonlinear hydro-turbine governing system.