| Self-priming Pump is a special centrifugal pump,which only need to be poured with water the first time it's turned on and the gas in the inlet and the pump can be exhausted in a short period of time.The pump then turns into normal working model of centrifugal pump.Due to its excellent characteristics,self-priming pump is widely used where it need to be frequently turned on and off,especially agriculture,electric power,fire protection,petrochemical industry,etc.Thanks to the complexity of internal structure and gas-liquid two-phase flow,no reliable theory have existed by now to reveal the internal flow law of self-priming pump.Boundary conditions and initial condition similar to the real working condition were adapted,numerical simulation and experimental investigation were adapted to study the stable phase and self-priming process in the conditions of two different valve opening.The work and conclusions of this paper are as follows:(1)The external characteristic of the selfpriming pump was theoretically calculated.The internal and external factors that affect the self-priming performance of self-priming pump were summarized(2)Fluid domain of self-priming pump was established with Pro/ENGINEER and grid of fluid domain was meshed with ANSYS ICEM.Steady numerical simulation was conducted in ANSYS CFX.Internal flow field and pressure field of single liquid phase were studied and the external performance was predicted as well as the cavitation characteristics.Flowmaster was also used to study the system of sel-primin pump and pipline,efficient area of self-priming pump was figured out and a new pipline system matching scheme was put forward.(3)ANSYS CFX was used to simulate the gas-liquid two phase flow under the condition of two different valve opening during the self-priming process.Distribution of speed,pressure and flow rate of these two phase from several monitoring points were obtained.A method which could estimate self-priming time was put forward and the influence of the valve opening on self-priming was investigated.The results indicated that during the initial stage of self-priming,the gas mass flow rate from each monitoring point showed a more obvious oscillation,and in the middle stage,it showed obvious pulsation.Volute is the main exhaust unit and reflowing hole played an important role in the gas exhaustion.The reduction of the opening of vavle was not good for the self-priming process.(4)External performance experiment and cavitation experiment were conducted,of which the results showed that simulation results were closer to the the actual operation of self-priming pump than the theoretical results. |
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