| The self-priming pumps belong to special centrifugal pumps. They need the water injectioninto the pumps only before the first starting of the pumps, and no more pump priming isneeded at the later starting of the pump. Due to their special characteristics, they are widelyused in agriculture, fire protection, petro-chemical industry, electric power, food and otherdepartment. Specially, in recent years, they are widely applied in the oil and gas storage andtransportation engineering.Recently, due to the widely use of the Computational Fluid Dynamics (CFD) and thedevelopment of the computers, researchers did a lot of studies on the simulation of thegas-liquid two-phase flow in the self-priming pumps which revealed the flow conditions andthe hydraulic performance inside the self-priming pumps to some degree. However, there aresome inaccuracies in these researches: almost all of these simulations are based on onehypothesis that the void fraction at the pump inlet is a constant value, which is used as theboundary condition in these simulations. However, in practice, there is a whole section of thesuction line being filled with air before the starting of the pump. During a short period of timeafter the starting of the pump, the void fraction at the pump inlet varies greatly with both timeand location. Therefore, there will be a big difference between the results of the simulationsabove and the real conditions. Concerned the problems mentioned above and on the basis ofthe summary of the researches on self-priming pumps and the simulation both in China andabroad, we did researches on the inside flow field and the self-priming process of theself-priming pumps, using the methods of theoretical analysis, both steady and unsteadynumerical simulation and experiment. The main work of this paper will focus on thefollowings:(1) By reading a lot of related papers, the current state of the research and the results of theformer studies about the self-priming pump are summarized. Introduced the working principleof the general self-priming pumps, and then elaborated the structure and the configuration, thehydraulic design of the flow passage components and the influencing factors of theself-priming performance of a kind of self-priming pump. (2) Made the performance test on the model pump of the self-priming pump. The head, thepower and the efficiency of the model pump at different flow rate on the performance curveare measured.(3) The three-dimensional objects of the flow region in the self-priming pump weremodeled by using Pro/ENGINEER, and the mesh was generated with ANSYS-ICEM.(4) The steady simulation on the inside one-phase flow will be made in the CFX. Thepredicted external characteristic curves will be got. We also got the characteristics of both thestatic pressure and the flow rate of the flow region inside the pump. At last, the comparisonbetween the pump performance curve from the experiment and the numerical simulation wasmade, and the reliability of the simulation was attested.(5) Made the unsteady numerical simulation on the flow region in the pump withANSYS-CFX. We studied the void fraction, the distribution and the characteristics of both thestatic pressure and the flow rate of the gas-liquid two-phase flow during the self-primingprocess of the pump. We made some monitoring points at the impeller inlet, pump outlet,volute outlet and the hole on the volute and monitored, recorded and analyzed the parametersin these areas. Finally, according to the gas flow rate at the pump outlet, we worked out amethod to estimate the self-priming time of the pump. Besides, we also studied the effect ofthe board settled in the gas-liquid separated chamber during the self-priming process. |
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