Advanced Materials Research Vols. 718-720

Abstract: A new spray desuperheater is designed, whose characteristic is using the combination technology of centrifugal nozzle and two-level venturi pipes. According to the application of the technology, the paper reveals the technical principle and structure design. The spray desuperheater has excellent spray atomization effect, and it can regulate the steam temperature in a wide range. So it can ensure the efficient heat exchanger and safe operation for boiler.

Abstract: Firstly, the development and principle of PIFA antenna in mobile phone are introduced, and the typical PIFA antenna design is analyzed. The PIFA antenna simulation is based on HFSS software. It is found that the high frequency bandwidth of this kind of antenna is very narrow. Then related parameters are optimized, by increasing the parasitic branch in high frequency band. Simulation results show that the return loss of PIFA antenna in high band is improved and the antenna can be expanded in high band, and matched in low band simultaneously.

Abstract: The 3-105 half isolated island fully mechanized caving face in Tengdong coal mine which in complex geological and high temperature condition, has a spontaneous combustion feature that is different from normal advancing mechanized caving face, such as slowly advance speed, stress concentration and air leakage of inside-impending gob. To overcome the dangerous possibility of spontaneous combustion between the roof coal seam inside-impending gobs, small coal pillar and adjacent gob of half isolated island fully mechanized caving face, analysis spatial structure of overlying strata roof and spontaneous combustion characteristics. Based on the result of pressure can be measured and tracer gas test of air leakage channels, determine the potential air leakage areas. The MEA plugging wind material is pumped into roadway and SPA-4 plugging wind material is spray around known air leakage or high temperature area to eliminate the hazards of spontaneous combustion of the potential danger zone, and protects the safe mining of the working face.

Abstract: Commonly used commercial simulation software SYSNOISE and ANSYS is run on a single machine (can not directly run on parallel machine) when use the finite element and boundary element to simulate muffler effect, and it will take more than ten days, sometimes even twenty days to work out an exact solution as the large amount of numerical simulation. Use a high performance parallel machine which was built by 32 commercial computers and transform the finite element and boundary element simulation software into a program that can running under the MPI (message passing interface) parallel environment in order to reduce the cost of numerical simulation. The relevant data worked out from the simulation experiment demonstrate that the result effect of the numerical simulation is well. And the computing speed of the high performance parallel machine is 25 ~ 30 times a microcomputer.

Abstract: Based on a technique of mixed programming with MATLAB and C#, the transmission parameters optimization software was developed to improve the power performance of off-road vehicle. The power loss rate and the starting acceleration time were chosen as objective function, and the requirements of the vehicle performance and the gearbox ratio interval was used as constraint conditions. The result of verification example showed that both objective function values are reduced after optimization and the effect of optimization with power loss rate is more significant.

Abstract: The spatial flow fields of turbulent boundary layer over a wavy wall were measured by TRPIV at three different Reynolds numbers in a water channel, the mean streamwise and wall-normal velocities near the wall were calculated from the time series of instantaneous spatial 2D-2C flow fields of turbulent boundary layer, and the periodic distributions of the streamwise and wall-normal velocity in streamwise direction influenced by the wavy wall were found. The spatial distributions of Reynolds stress and mean velocity strain rate were obtained by ensemble average. Using the spatial cross-correlation technique, the spatial phase relationship in streamwise direction between mean velocity strain rate and Reynolds stress was investigated. It is found that there exist spatial phase differences between Reynolds stress components and mean velocity strain rate components, the phase differences increase gradually after decrease gradually from zero away from the wavy wall in wall-normal direction and reach a minimum at 0.4~0.5 times the wavelength of wavy wall, and in a certain range the effect of the Reynolds number on the phase differences is very small. The reasonability of the complex eddy viscosity model is confirmed by these experimental evidences in order to forecast non-equilibrium turbulence accurately.

Abstract: The pre-stressed modal properties of planetary gears of compound oscillatory roller transmission gear reducer considering the external torque and rotating angular velocity were calculated in this work. For the boundary conditions, the large torque was considered to output gear and angular velocity for applying to middle gear. The resonant frequencies of output gear under external torque were a little higher than the case of no external loads, because the stiffness of gear will be changed with external loads. But the resonant frequencies of middle gear show the no changes under rotating angular velocity, because the low angular velocity and no stiffness change with structure of gear. Finally from the cambell diagram, the calculated resonant frequencies were in the range of safety.

Abstract: According to the current global energy shortage crisis, a kind of generation device for hybrid power of wind and wave is designed. The basic components of the power generation device and the design plan are introduced, and also the working process of the device is elaborated. In the design process, the two energies are superimposed and mixed by the ratchet mechanism and addition institutions. This mixed approach is feasible by theoretical calculation, and the design inadequacies are found in the calculation process, so the power generation device is improved. The device is of good mixing and superimposing on wind and wave energy, the structure of power generation device is stable and reliable, and the device owns certain referenced value to the future research on generating power by wind and wave at sea.

Abstract: Digging performances of excavator is a key important index for evaluation of excavator. It is a very complex and heavy work to compute digging performance of excavator. So a compact hydraulic excavator model was built by ADAMS software. The theoretical maximum tool force of excavator was analyzed. For bucket digging mode, the maximum tool force were analyzed for boom cylinder seven positions during the whole working range and the effect of different factors were discussed. The practical maximum tool force was gained. The actual tool force variations were found through the analysis of simulation results. It provides the basis for design and improvement of excavator.

Abstract: A Voice Coil Motor (VCM) for precise positioning with high output force was designed. The stability and heat dissipation of VCM were analyzed. The performance of VCM was also compared with that of the same type VCM produced by SMAC. Uniaxial ratcheting behavior of solder wire (Sn63/Pb37) was studied by uniaxial cyclic stress controlled tension deformation tests,to verify the VCM systematically.