Based on the discrete phase model (DPM) solid–liquid two-phase flow model and MATLAB image processing technology, an integrated prefabricated pumping station was taken as the research object to study deposition characteristics under different flow rates, different particle diameters, and different liquid levels. Considering the incomplete symmetry of the internal flow of the prefabricated pumping station, deposition characteristics of the prefabricated pumping station under single/double pumps were also analyzed. Double pumps were symmetrically distributed in the integrated prefabricated pump station, and the movement trajectories of particles at the bottom of the pump pit under the closing inlet valve were measured through the use of a high-speed photography experiment. Results showed that with the increase of the flow rate, the deposition rate of the separated prefabricated pumping station decreased. With an increase of the particle diameter, the movement of particles was farther away from the vertical barrier weir. In the range of particle diameter of 6 to 10 mm, the deposition rate decreased with the increase of the particle diameter. With the increase of the liquid level, the deposition rate decreased, first, and then increased again. In the case of the single pump operation, the deposition rate of the right pump operation was smaller than that of the left pump operation. The variation of the deposition rate when the right pump operated was basically the same as that when the dual pumps operated. The movement path of particle N1 was longer. With the decrease of the flow rate and the increase of the particle diameter, the following feature of the particle decreased, and it was easier to impact the walls and edges, which caused long-term deposition. The research results could provide some suggestions for the design of anti-deposition performance of prefabricated pumping station.

No abstract

In order to improve hydraulic efficiency, influence of inlet angle, outlet angle, wrap angle, inlet shape and outer edge camber lines of channel-diffuser blades on the energy performance of a three-stage centrifugal pump were studied and the pressure distributions on the blade of the first-stage channel-diffuser were particularly analyzed. The result shows that the efficiency of the pump is maximal when the blade inlet angle is 12°. The pressure variation in the model with the inlet angle of 12° was small and the amplitude of fluctuation was also not large. When the outlet angle was 90°, the pressure distribution in the outlet of the blades that are symmetrically distributed along the center of the diffuser shell was significantly better than that with other outlet angles. The effect of the blade wrap angle of the channel-diffuser on the energy performance of the pump was relatively small. The internal flow in the diffuser with the diffusion inlet shapes was steady for both the convex surface and concave surface. The diffusion inlet of the channel-diffuser blade corresponded to the outlet region of the impeller blade, which reflected a good matching. The fluctuation amplitude and the distribution range of the models with a uniform transition were smaller than those with non-uniform transition. In order to verify the effectiveness of the research results, an experimental test was carried out on the pump. The results show that when the flow rate is 850 m3/h, the head of the pump is 138.67 m and the efficiency of pump is 69.48%.

Based on the discrete phase model (DPM), solid–liquid two-phase flow calculation, particle settling theory and MATLAB image processing technology, the influence of the installation position of submersible pumps on the deposition characteristics in a cylinder-type prefabricated pumping station was studied, and two performance indices, the deposition rate and area ratio of the easy deposition region were proposed. The results show that the area ratio and deposition rate of the easy deposition region increase as the suspension height increases. The discharge effect is best when the suspension height is 0.1H0, however, at this time the inlet bias of the pump is larger, which is not conducive to the smooth operation of submersible pumps. The area ratio and deposition rate of the easy deposition region gradually increase with the increase in the interval of the pumps. As the center distance increases, the area ratio and deposition rate of the easy deposition region basically decreases first and then increases, and reach the minimum at 0.1R and 0R, respectively.

To broaden the database of fire equipment selection and provide the basis for its selection and optimization, a low specific speed centrifugal fire pump with a specific speed of 24.7 was selected as the research object, and the inlet and outlet pressure pulsation and cavitation characteristics under different flow rates were analyzed through experiments. Results show that the head of the fire pump under the design flow rate was 75.68 m, and the efficiency was 36.84%. The dominant frequency of the pressure pulsation in the inlet and outlet of the pump under different flow rates is 1 APF (axial passing frequency). The zero flow rate has no obvious peak distribution at 1 BPF (blade passing frequency). The secondary frequency of 1 BPF and the n times the harmonic frequency of 1 BPF are distributed in the outlet of the pump. The critical net positive suction head of the fire pump under 1.0  Qd and 1.5  Qd was 0.95 m and 2.38 m, respectively.