Fluid-structure Coupling Analysis Of Surface Integrity Dependent Hydraulic Characteristics For Nuclear Main Pump

The nuclear main pump is a rotating equipment in the nuclear power plant,which is used to drive the working medium from nuclear reactor core to circulate.Its overflow parts are mainly composed of impeller,guide vane and annular pressurized water chamber.Compared with other overflow parts,impeller,as the only rotating overflow parts in nuclear main pump,plays a leading role in the hydraulic performance of nuclear main pump.However,the engineering surface of the impeller will cause instability of the flow field,which may cause the vibration of the nuclear main pump to affect its long-term safe and stable operation.In this paper,the whole flow passage of the overflow parts of the nuclear main pump is modeled by the Solid Works.Based on the bidirectional fluid-structure coupling method,the fluid-structure coupling simulation of the flow field of the nuclear main pump and the impeller is carried out through the finite element software ANSYS,and the influence of the impeller surface integrity on the hydraulic characteristics of the nuclear main pump is studied.Under the ideal smooth surface of the overflow parts of the nuclear main pump,considering the fluid-structure interaction between the solid and the flow field,the external characteristic parameters such as the head and efficiency of the nuclear main pump under different flow conditions decrease slightly,and the amplitude of the pressure pulsation in the impeller passage decreases,but the small deformation of the impeller will cause the pressure pulsation in the guide vane passage to rise.Considering the engineering surface of the overflow parts,the roughness equivalent factor C_eqand surface roughness have obvious influence on the head and efficiency of the nuclear main pump.With the increase of roughness equivalent coefficient C_eqand surface roughness,the head and efficiency of nuclear main pump increases and decreases,and the turbulent kinetic energy of impeller blade surface decreases and increases,respectively.The pressure fluctuation at different monitoring points of impeller presents two different trends,and the inlet and middle region of impeller increase and decrease,respectively.In the impeller outlet and the guide vane channel,the change of pressure pulsation is opposite to that of the impeller inlet.In addition,the range of the alternating radial force load on the impeller decreases and increases,respectively.The hydraulic performance of nuclear main pump depends not only on the surface roughness of overflow parts,but also on the surface integrity related to the roughness equivalent factor C_eqof overflow parts.Therefore,the surface integrity of the overflow parts of the nuclear main pump is an important factor affecting the hydraulic performance.