Key Engineering Materials Vol. 561

Abstract: This work presents the effect of V cut and square cut rotors in circular tubes for turbulent heat transfer using computational fluid dynamics (CFD) modeling. The computational results are in good agreement with experimental data. The obtained results reveal that the use of square cut rotors leads to higher Nusselt number than use of V cut rotors. The results also show that the heat transfer rate, friction factor and thermal performance factor of rotors with square cut increase with the increase of width (a) and depth (b) of rotors’ cut. Square cut rotors with a=b=3 yields higher mean thermal performance factor than those with other width and depth, a=b=1, 2 and the highest thermal performance factor of square cut rotors at a=b=1, 2, 3 are found to be 2.08, 2.11 and 2.13.

Abstract: With the computational fluid dynamics software FLUENT, three dimensional gas-solid two-phase flow field was simulated and analyzed for HMC-64 pulse-jet cleaned bag-type collector. The simulation data and the actual operating parameters were compared, and the airflow distribution of bag-type collector was comprehensively learned. On the basis of the original analysis, the reconstruction about flue-gas rich-lean separation combining lateral extension at the entrance of bag filter was put forward. The velocity distribution and the mass flow rate of all filter bags were compared. Results showed that through using rich-lean separation combining lateral extension, the airflow distribution of each filter bag was optimized. The integrated flow non-uniform amplitude and the relative root-mean-square value became lower than those of original model. These conclusions about the structural modification and the airflow optimization provide theoretical foundation for further research.

Abstract: This paper introduces vectorization technology fromTrueType font for the text on the sidewall plate of the tire mold. TrueTypefont processing technology is the extraction of Windows functions and datatypes of the font outline. Call the API function to process the text in orderto achieve the CNC Machining of the text. It completes the tire mold word-processingsoftware on this basis. The software enables a variety of functions includingtext layout, font zoom, font spacing adjustment, font choice. It also providesa rapid tool for the quickly arranged and CNC machining of the text on thesidewall plate of the tire mold.

Abstract: The multiaxial stress is acted on the sidewall and beams of the large linear vibrating screen. So the critical plane method is used for calculating the fatigue lives of the large linear vibrating screen. The logarithm fatigue lives nephogram is drawn and the logarithm fatigue lives of large linear vibrating screen are analyzed. The local logarithm fatigue lives for different surface roughness of the vibrating screen is calculated and the results shows that the fatigue lives decrease quickly when the surface roughness increases.

Abstract: The tower circular escape apparatus based on the principle of escapement mechanism is introduced in the paper. The emergency evacuation device for fire trapped workers can be used in the place of frequent fire, hotels, office buildings, high-rise residential and stores, etc. The velocity of the principal axis can be controlled automatically by the escapement mechanism. The driving force of the escape apparatus comes from the gravity of the trapped workers. The experiment results show that the velocity of the device can be controlled on the operating range. The symmetrical structure can make more persons with different weight escape alternately and the velocity of descend approximate. In the research, the virtual prototype technology was used to analyse the kinematic characteristics of the mechanical system. The feasibility of the scheme design of mechanical system was proved with the simulation analysis results. The equipment has advantages of the structure is compact, safe and reliable, easy to use. The research of tower circular escape apparatus based on the principle of escapement mechanism can be regarded as the reference of the related research.

Abstract: When we use Coordinate Measuring Machine to measure some points of the workpieces, the wrong measuring method will get the poor repeatability and poor reproducibility of measurement results. Now the vector measure of the CMM is a more convenient way. The main principles are analyzed in this paper, and a workpiece is measured for example.

Abstract: In this paper, the vertical-parallel type steel bracing structure of the porous fences is taken as research object, which is applied in the dust control package engineering devices in some power plant in Hebei Province. After two-dimensional finite element model of steel bracing structure was established by ANSYS, the mechanical characteristics with wind loading have been analyzed. Furthermore the strength, stiffness and stability have been checked. The research results will provide helpful theoretical support to optimize the structure and reduce the investment cost of the porous fences engineering.

Abstract: The self-cleaning sole cleaner designed in this paper is a kind of cleaning device widely used in large public places. It possesses functions such as washing, wiping, drying and self cleaning, and so can thoroughly clean sole. It is chiefly composed of pressure washing unit and self-cleaning wiping unit. The device washes the sand and mud adhered to sole by the pressure water coming out of the pressure cleaning head at first, and then wipes off the sole sewage by the wiping unit, finally dries sole. Main advantages of the cleaner are concluded to simple structure, good cleaning effect, energy saving, and environmental protection by adopting the technologies of water level automatic keep and sewage dispose.

Abstract: For friction design, the antifriction model of self-lubricating tool was built. Al₂O₃/TiC/CaF₂ was prepared, and the chemical compatibility of Al₂O₃/TiC/CaF₂ was analyzed and calculated and the results were verified by X-ray diffraction patterns. The microstructure design of self-lubricating tool material was discussed. The results show that it can reduce the friction coefficient if solid lubricating film can be produced on the friction interface, even the lubricating film can't completely be formed on the friction interface. Under high temperature, there were no reactions in Al₂O₃/TiC/CaF₂. To form continuous net structure of matrix and reduce the friction, the solid lubricants content should be moderate. According to analysis of the particle packing ways, the radius ratio between solid lubricant particles and ceramic matrix particles was confirmed and it should be within the scope of 0.225 r / R 0.414.

Abstract: Underwater pipelines of oil and gas need periodic inspection to prevent damage due to the biological activity of water, turbulent current and tidal abrasion. Currently, vision-based autonomous underwater vehicle plays an important role in this field. A system has been designed to help an autonomous vehicle in sea-bottom survey operation. Image understanding and object recognition directly affect the accuracy of inspection. An image smoothing method based on mathematical morphology is proposed. The disturbances on acquired images caused by the motion are partially removed. A series of algorithms about image preprocessing, segmentation and recognition are proposed to access pipeline contours from the top-view images effectively. Navigation data based on Hough transformation is presented after the analysis of contours. Finally, the processing effect on a pipeline image demonstrates the effectiveness of the system.