Applied Mechanics and Materials Vols. 448-453

Abstract: Based on the establishment of angular contact ball bearing mechanical model, a nonlinear coupled lateral, torsional and axial dynamic model of helical gear-rotor-bearing system is established, and the dynamic differential equations of the coupled lateral-torsional-axial nonlinear vibration are deduced for imbalance rotors. The investigations are systematically carried out by oscillograms and spectrograms with rotating speed, taking into account eccentricity and nonlinear supporting by rolling bearing. The results show that the rotation frequency of the driven shaft appears in the driving shaft. In addition, the rotation frequencies and meshing frequency appear obviously in torsional direction. It can be seen that the lateral, torsional and axial response characteristics of driving and driven shafts obvious differences are due to the effects of the gear assembly characteristic, gear geometry parameters and the angular contact ball bearings characteristics. As a result, not only appear the rotational frequency and stiffness frequency, but also yield the bearing variable stiffness frequency and conbined frequency in lateral directions. However, the theory of the helical gear-rotor-bearing system still needs further research.

Abstract: Numerical simulation was conducted on three types of swirl chamber of turbulent combustion diesel engine, i.e. cone-shaped flat-bottomed, cylindrical flat-bottomed and spherical shape. The characteristics of flow field in cylinder were studied within the time range for the piston to move from BTDC 108°CA to BTDC 8°CA (at the instant of fuel injection), thus analyzed the changes of flow field in swirl chambers of such three different structures prior to fuel injection based on the velocity vector diagram at all times and the final temperature characteristic diagram of the flow field. The results show that: in the process of piston motion, an organized fierce vortex can be developed inside the swirl chamber, while in the vicinity of fuel nozzle, the air flow rate is 111.14m/s, 83.01m/s or 175.76m/s and the air temperature is 1384.15K, 1337.38K or 1350.46K respectively. A small fluid stagnation zone will be formed in the lower right end of the cone-shaped flat-bottomed swirl chamber or the cylindrical flat-bottomed swirl chamber and is adverse to the mixing of fuel and air. In comparison with the swirl chambers of other two structures, the smaller temperature gradient of fluid and the larger high-temperature area in the cylindrical swirl chamber are beneficial to the mixing of injected fuel and air.

Abstract: An advanced experimental rig for heat pump water heaters was established. The performances of both a phase change heat-storage-type heat pump water heater (Type A) and a conventional heat pump water heater (Type B) were tested and compared according to GB/T 23137-2008 using the experimental rig. The results showed that the existence of phase transition temperature platform enabled the phase change heat-storage-type heat pump heater run longer and more steadily. When the same hot water heat capacity obtained, the volume of the accumulator in the Type A water heater accounted for about 56.9% of that of the water tank in the Type B water heater, which could save the overall size of water heater significantly and therefore promote the wide application of energy-saving heat pump water heaters.

Abstract: Coiling temperature control (CTC) is very important to the quality of the strip steel in Hot Strip Rolling Mill. In the paper, genetic algorithm and neural network method to predict coiling temperature on hot strip mill were put forward. The genetic-neural network was trained and checked with actual production data. The result indicates that the method can real-time predict the strip coiling temperature. The on-line prediction model and step track method has been put into use. The result shows that the method can settle lag influence in feedback control and the CTC control precision is improved greatly.

Abstract: Due to the fact that it is generally difficult to accurately calculate the nonlinear section of flow characteristics curve of small injection pulse width of electronic control injector, it is impossible for electronic control unit (ECU) to accurately control fuel injection quantity when the small engine such as motorcycle is under a working condition of idle speed or small load. This paper introduces the principle and method to make a fitting for flow characteristics of nonlinear section in the developed software system in details. Take the electronic control injector of motorcycle as an example, the programming method combined with LabVIEW and MATLAB is utilized to make a fitting treatment for accurate fuel injection quantity obtained via measuring single-chip microcomputer through Smoothing Spline method, so as to obtain the flow characteristics of small injection pulse width and normal injection pulse width of electronic control injector of motorcycle.

Abstract: This paper analysed the working parameter of hydraulic roofbolter. Modeling and simulation were established based on AMESim. Analysed change of pump input traffic, piston velocity and displacement, impact frequency on basis of simulation curve. Also analsyed the influence of hydraulic impactor, providing theoretical basis for impact characteristics research.

Abstract: The Paper has Established a Combustion Model of Lean-Burn CNG Engine by Three-Dimensional Simulation Software AVL FRIE. Based on Test Validation in the Model, the Combustion Processes of Seven CNG Samples were Simulated and Compared from the Intake Valve Closed to the Exhaust Valve Opening. the Effects on Different Composition Fuels for CNG Engine were Researched. the Results Showed that: the Maximum Average Pressure within the Cylinder , the Highest Average Temperature, the Maximum Heat Release Rate, the Initial Mass Fraction of Fuels, CO and NO Formation Increased with the Hydrocarbon Fuel Ratio C/H, the Composition of Heavy Paraffin in CNG Directly Affected the Performance and Service Life of the Engine.

Abstract: As an effective and economic technique for flow range enhancement, casing treatment is widely employed to increase stability margin of compressors. In order to explore the effectiveness of casing treatment on performance of centrifugal compressor under multi-working conditions, in the present thesis, numerical analysis of three kinds of inlet recirculation casing treatment and a smooth untreated casing compressor models were carried out. The numerical results coincide well with the experimental data of optimal model and accurately predict the position of surge line, which verifies the reliability of numerical method which applied in this thesis. The results also indicate that, only reasonable configuration of the inlet recirculation casing treatment could significantly enlargement the stable operating range of the compressor at low flow rate under all rotation speeds. In addition, the slot position and front deflector baffle of the casing treatment have a great impact on its performance.

Abstract: A computational model of a GDI engine is established by 3D CFD simulation software. A simulation on the formation of mixture of the engine under 1500r/min, full load conditions are carried out. The calculation results provide a reference for the optimizing of the engine.

Abstract: Use the standard 750ml bottle of red wine packaging design to explore the honeycomb core module of digital design and green manufacturing approach to virtual design and virtual manufacturing of new structural approach to packaging product development, through the final product form of reverse thrust reversers honeycomb core module data and processing forms, and finally the use of CNC machining centers cellular module manufacture.