Influence of Copper Shield Structure on 3-D Electromagnetic Field, Fluid and Temperature Fields in End Region of Large Turbogenerator

A new kind of the copper shield structure called the empty solid copper shield structure (ESCSS) in the large turbogenerator is proposed in this paper. Based on the complex structure characteristics of a 330-MW water-hydrogen-hydrogen cooled turbogenerator, the flow network within a half of the generator is established, and the total flow rate, pressure, flow rates (boundary conditions) of the various ventilation ducts and the chambers in the generator are separately obtained after solving the equations of the flow network when the traditional copper shield structure and the ESCSS are adopted. The 3-D transient electromagnetic field of the generator end region is calculated by using the time-stepping FEM, and the electromagnetic loss distributions (heat sources) are determined separately. Then, the fluid and thermal analysis model for the whole end region is established. Through numerical calculating, the whole end region 3-D fluid and temperature distributions are obtained separately. The results show that the new copper shield structure makes the copper shield temperature much lower. Meanwhile, the copper shield material is saved. The obtained conclusions may provide useful reference for the optimal design and research of the large turbogenerator.