Applied Mechanics and Materials Vols. 341-342

Abstract: The dimention for muffler has great impact on the car engine. Based on software GAMBIT, GT-POWER,SYSNOISE,through comprehensively using finite element and boundary element method,simulating and analyzing the acoustic performance for the basic noise reduction unit,establishing the finite element model, comparing the frequency and noise reduction of different volume ratio of cavity and throat tube.Simulation analysis and experimental results show that the resonant structure parameters have a direct effect on its resonant frequency and noise reduction amount. the relationship characteristic between them is that the ratio more bigger,the requency and noise reduction amount more bigger , too.And draw the two relation formulas through calculation.

Abstract: The velocity and diameter distribution of the air-assist boom spraying is studied by a laser Phase Doppler Partic1e Analyzer when the operational parameters is changed, which including airflow velocity of air curtain and vertical relative position between the air curtain and the nozzle. From the experimental results, we find the as the air curtain velocity increases , the size distribution of the droplet is conducive to uniform . At the same air curtain velocity, droplet size decreases with increasing of nozzle pressure. On the right side of each measuring point, the number of droplets is gradual decreasing with the wind velocity increasing.When the working pressure is 0.5Mpa, the droplet size does not change with the change of the horizontal distance.

Abstract: In order to study the internal flow characteristics of roto-jet pump, the standard turbulence model and SIMPLEC algorithm were used to calculate the three-dimensional turbulence flow field under design condition. The simulation results reveal the internal flow phenomena of roto-jet pump, which shows the pressure near the suction surface and the inlet edge of impeller is minimum, and the cavitations is easy to occur . At the same time, the circumfluence and flow separation phenomenon is not found in the vicinity of the short blade, which is used to shunt the flow. The pressure gradient changed little in the rotor cavity. Is easy to form vortex at manifold import corners, there is no vortex generated on the second corner when the diffusion tube is used. The results obtained in this research provide a theoretical foundation for improving pump performance and reduce the hydraulic loss.

Abstract: For engine oil sump structure, using the finite element method, considering the engine vibration analysis of structure. Get the stress distribution of the engine oil pan through the modal analysis optimization to make it comply with the design requirements.

Abstract: According to the characteristics of the vertical axis wind turbine, research about the mechanical analysis and inherent frequency in design of the small vertical axis wind generator pole is complete, and simulation on the influence of the structure forms and pole wall thickness on natural frequency has been done. The results can help solve the problem such as resonance between the wind turbine pole and the rotating turbine.

Abstract: Nozzle plays an important role in steam turbine design and operation. With the purpose of design a new type low pressure saturated steam turbine, in this paper the model of steam flow inner nozzle was simulated, and the influences of tip angle, expansion section length and throat length on the efficiency of the nozzle were analyzed. Furthermore, the structure and parameter of nozzle were optimized.

Abstract: In order to improve dynamic characteristics of air spring with auxiliary chamber, finite element model of air spring R1A390-295 with auxiliary chamber connected with pipe is established,and through analysis to the dynamic characteristics of the model, influence discipline of sitffness characteristics to air spring with different pipe, different auxiliary chamber or different initial pressure are analysed under different excitation. The result show that:minor dynamic sitffness is obtained by using larger pipe or under lower excitation frequency,and as volume of auxiliary chamber increases, the spring dynamic sitffness will decrease accordingly and its amplitude tends to gentle,and influence for decreasing the spring dynamic sitffness is not obvious by continuing to increase the auxiliary chamber volume; the spring dynamic sitffness will increases as initial pressure increases. The validity of Finite element model is verified through dynamic characteristic test .

Abstract: According to the LaGrange energy equation, the establishment of the unsteady oil film force of the rotor - stator - bearing system dynamics model, the application of numerical method, the system with the speed change time domain waveforms, amplitude spectra and Axis Orbit, the results show that: the unsteady oil film force and speed of change is closely related to changes in the process of oil film force oil whirl Oil Whip. Provide a theoretical basis for effective diagnosis of rotor - stator - bearing oil film instability fault research.

Abstract: In ship pitch balance system, serious flow impact and water hammer occur because of the turning on and off of valve during the procedure of water-shift. Flow area of the ball valve used most on ship was derived, and mathematical models of pressure lost before and after valve were formulated. Besides, considering the fact of water-shift balance system, an AMESim model was established based on improved traditional throttle model. And the validity of AMESim model was ascertained by comparing simulation results of stable pressure before and after valve with calculated values from mathematical models. Then, with the AMESim model, impact characteristics of water-shift pipeline were investigated when adopting various valve switch rules, length of pipelines before and after valve and using an accumulator in system. From that, methods to reduce pipeline impact were proposed, which make good references for noise control of ship pitch balance system.

Abstract: Improvement design was carried out to resolve the issue about easily damaged and difficult repaired planar seal for hydraulic fast connector. Through adding a taper on male connector and female regulating part on female connector, the co-planar seal was changed into the taper seal which the seal was more reliable. When the contact surface was worn, it can be resealed by adjusting the female regulating part. Taper seal was key to design the reasonable taper. In order to acquire the best taper, taper optimal design was carried out using finite element technology, the relationship between maximum contact stress and tape was gained. Simulation results showed that the best taper could be gained when the big-endian radius of the taper was 11.82 mm.