Because disk friction loss of ultra-low specific speed centrifugal pump accounts for a large proportion of shaft power, it is important for accurate calculation of the loss. According to the structure of the pump and the characters of the flow of the fluid in the pump cavity, a new disk friction loss formula is put forward, which considers to add two important factors that include the leakage influence coefficient and geometric size of pump cavity. By means of CFD method, according to the results of numerical calculation prediction and test performance curve, the following conclusions are obtained by comparison of accuracy among the new formula and two existing disk friction loss formulas: the new formula is more suitable for calculation of ultra-low specific speed centrifugal pump disk friction loss compared with existing formulas.
With the development of intelligent manufacturing technology, 3D printing technology is also developing rapidly.This paper mainly studies the thermodynamic changes of different nozzle materials in FDM melt deposition technology of 3D printer at a certain temperature.ANSYS software is mainly used to simulate and compare the heating of copper nozzle and aluminum alloy nozzle. Through comparison, it is found that the deformation, i.e. thermal expansion of aluminum alloy material after heating is greater than that of copper alloy material.
Under the condition that the main geometric parameters of pump remained unchanged, the optimization of pump performance was realized by reducing the effective flow area ratio of impeller outlet and inlet. The effective area ratio of impeller outlet and inlet was changed by means of quasi orthogonal method. With super-low specific speed centrifugal pump M23-12.5 as the research object, on the basis of the pump test results, the paper constructed 7 different impellers which were different effective flow area ratios and were loaded into the same complete casing geometric model including the front and back of the pump cavity and the seal rings. With CFD method, this paper analyzed the effect of different effective flow area ratios of impeller outlet and inlet on the performance and the distribution of flow field structure of super-low specific speed centrifugal pump. The results showed that with the impeller effective flow area ratio decreased, head and shaft power had a decline in varying degrees at the same time efficiency increased. Thus on the premise of improving efficiency, area ratio should be reduced appropriately; with the further narrowing of the impeller flow passages the internal axial vortex flow and the hydraulic loss became smaller; because the absolute speed of the impeller exit increasing after the passages narrowing, vortex near the tip clearance of impeller was enhanced and hydraulic loss was increased.
With the rapid development of China's economy, the design of bridges has also made considerable progress. Starting with the model requirements and competition rules of the comprehensive ability competition of engineering training, this thesis designs an arched truss bridge after comparing the concentrated bridge structures. The bridge has simple structure, clear and concise stress and beautiful appearance, and can give full play to the compression resistance of paper made from bamboo. The finite element analysis software ANSYS is used to analyze and calculate the strength, stiffness and stability of the bridge model. The experimental results prove that the designed bridge can bear the load of 20 kg.
Special shaped stone products have the characteristics of individuation, diversity and artistry, and are mainly produced in single piece and small batch, which requires its processing equipment to have flexible production capacity. Traditional manual processing and simple stone equipment can not meet the high-speed production needs of special-shaped stone products. According to the special process of special-shaped stone, the structural topology optimization calculation and analysis of beam rib plate structure is carried out by using MATLAB programming language, and the sand cleaning hole of beam are optimized and analyzed by using topological opt module in ANSYS, and a new beam structure is obtained. The analysis results show that compared with the original scheme, the new scheme not only reduces the weight, but also effectively improves the static and dynamic performance of the beam, achieves a good optimization effect, and lays a theoretical foundation for practical production.
As one of the core components of drilling and tapping machine, the spindle box unit of drilling and tapping machine is connected with the spindle unit of drilling and tapping machine on the bearing and fixed with the column unit of drilling and tapping machine through linear guide rail. Its stress and deformation have an important impact on the geometric accuracy and service life of the whole drilling and tapping machine. In this paper, the spindle box element of i5M1.4 drilling machine is studied. The maximum stress and strain of the spindle box are obtained from the static finite element analysis, and the first six natural frequencies and vibration modes of the spindle box are obtained from the modal analysis.
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