Structural Design And Research On Two Three-Way Magnet Valve

Backwashing of the automatic-backwash laminated filter is controlled by two three-way magnet valve. In this thesis, structure design for the two three-way magnet valve was carried out and as the water strike phenomena during the commutation process could be produced easily, a dynamic simulation for the lowing process of the stem was performed using the dynamic griding technology of FLUENT. As a result, the relationship between disc forms, commutation time and water hammer pressure during commutation process is obtained. Solutions to overcome such valve water hammer are proposed by optimizing disc shapes and reversing time. Comparison finds that the numerical simulations for the water hammer pressure well agree with the experimental measurements.Firsly, Based on the stress analysis and strength assessment for the key parts of the valve, structure design for the two three-way magnet valve was completed referring to the latest design standards at home and abroad.Secondly, steady meshing model of the valve's filtering as well as backwashing states was established by using Gambit 2.3.16, and the reversing process was analyzed and classified into 4 stages, namely decreasing process 1, 2 and rising process 1,2. The initial dynamic meshing model for each stage was made with Gambit and corresponding boundary conditions were given. Then, the model was imported into FLUENT6.3.26 to carry out the steady state and dynamic simulations for the commutation process of the two three-way magnet reversing valves. The simulation results show that no cavitation erosion and water hammer phenomenon happen according to speed and pressure distributions at the final moment during the reversing process.Thirdly, beside the common used quick opening disc of the two three-way magnet valve, three typical regulator discs were also used for the main valve and compared for their water hammer pressure during the disc lowing process. It is found that pressure of the quick opening disc is higher in the initial phases of the disc lowing process, and so for a safer operation, the regulator disc should be recommended.Fourthly, comparing the water hammer pressure with different commutation time during lowing process 2 and rising process 1 reveals that when disc rises in a different time, the position and magnitude of the maximum pressure are also different. Therefore, it is recommended that simulations for different commutation time should be performed to find out the position of the maximum pressure and, thus, take necessary measures, as locally thickening valve body for example, to increase the body's strength and ensure the safe operation of the valve. It turns out that the shorter the reversing time, the more uneven of the pressure distribution and the greater of the pressure difference of the valve's flow field are. In such case, the valve will not work so stably and the vibration of the valve's body could be induced easily.