| In nuclear power plant, the reactor coolant pump (also called unclear main pump) is the heart of the nuclear island, and is only high-speed rotating equipment in the nuclear island. Its performance and stability directly affect the nuclear power plant generating capacity and safety.The flow passage components of nuclear main pump are mainly composed of three parts:impeller, guide vane and annular casing, annular pumping chamber has a complex flow and less research on it at present. In this paper, regard the model pump of AP1000 nuclear main pump as the research object, the numerical simulation method is used to calculate full three-dimensional numerical simulation for the flow within the pump, obtaining the internal flow law of annular casing. The main research content was divided into the following three parts:1. Internal flow steady characteristics of nuclear main pump annular casingSteady characteristics of internal flow in annular casing under different flow rate conditions are been researched. The results show that it is nonlinear relationship between hydraulic loss of annular casing and flow rate. The flow rate along the annular basin in the annular casing is increasing gradually along the main flow direction, but the flow rates in the outlet diffuser at different working conditions are different. With the increase of the flow rate, the turbulent kinetic energy of the annular casing exhibits the change of the first decrease and then increase. Under different conditions, the change of vortex intensity near the right tongue leads to annular casing internal flow field changing, thereby affects the annular casing flow rate changing.2. Influence of tongue blend on the internal flow characteristic of annular casingThe influence of tongue blend on the internal flow characteristic of annular casing is been researched. The results show that the tongue blend has a certain influence on the performance of the annular casing, but it has little influence on the performance of the impeller and the guide vane. Under the design condition, the best performance of the annular casing is optimized by the presence of the optimal tongue blend. The greater turbulent kinetic energy position of annual casing is mainly produced in a quarter of annular fluid region which rotates along the main flow direction starting with the center of outlet diffuser.3. Influence of circumferential position of guide vane on the internal flow characteristic of annular casingThe influence of circumferential position of guide vane on the internal flow characteristic of annular casing is been researched. When circumferential position of guide vane changes, the annular casing hydraulic loss appeared distribution of high and low interval. Under the design condition, the maximum difference of the hydraulic loss is minimum, and off design condition, the maximum difference is increased. Under different conditions, the influence of the circumferential position of guide vane on the turbulent kinetic energy, the flow rate and the velocity distribution in different position of the annular casing is different. When the circumferential position of the guide vane change, the vortex shape is changing, with the increase of the flow rate, the main position of vortex area gradually extends downstream along the main flow direction in the annular basin. |
