Effect of cavitation flow on energy transfer in nuclear main pump
CHENG Xiaorui1,2*, FU Li1, BAO Wenrui1
(1.College of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China; 2.Key Laboratory of Fluid Machinery and Systems, Gansu Province, Lanzhou, Gansu 730050, China
In order to study influences of cavitating flow on energy transfer in nuclear main pumps, the cavitating flow field in a nuclear main pump model was carried out under design condition using the RNG k-ε turbulence and Rayleigh-Plesset cavitation models, then vapour bubble distribution features in the impeller were attained. The influences of cavitating flow on the energy transfer in the impeller were studied under different cavitation conditions by analysing variations of fluid kinetic and sta-tic heads along the two streamlines on the shroud and hub. Results showed that the energy of fluid was provided by the impeller in the middle and after-middle portions of blade, and the working capacity of blades decreased gradually from the shroud to the hub. Cavitation interfered with the flow in the impeller, leading to an increased relative velocity and a decreased pressure in cavities, and the working capacity of blades was almost zero in a zone with dense vapour bubbles. In non-cavitation zones, the kinetic head rose but the static head declined along the streamlines with the development of cavitation. Because the decrease in the static head was greater than the increase in the kinetic head, the pump head and efficiency had to be reduced. In addition, with the development of cavitation, the sudden change in both heads were intensified in the cavitation zones, resulting in an increased hydraulic loss in the impeller, eventually, the pump head and efficiency dropped off even further.
WANG Xiuli, WANG Peng, YUAN Shouqi, et al. Analysis on transient hydrodynamic characteristics of cavitation process for reactor coolant pump[J]. Atomic energy science and technology, 2014, 48(8):1421-1427.(in Chinese)
WANG Xiuli, YUAN Shouqi, ZHU Rongsheng, et al. Transient flow characteristics of nuclear reactor coolant pump in recessive cavitation transition process[J]. Nuclear power engineering,2013,34(3):71-76.(in Chinese)
ZHU Rongsheng, CHEN Zongliang, WANG Xiuli, et al. Numerical study on cavitation characteristics of CAP1400 nuclear main coolant pump[J]. Journal of drainage and irrigation machinery engineering, 2016, 34(6):490-495.(in Chinese)
SHI Suguo, WANG Guoyu, HU Changli, et al. Experimental study on hydrodynamic characteristics of cavita-ting flows around hydrofoil under different water temperatures[J]. Journal of mechanical engineering, 2014, 50(8):174-181.(in Chinese)
张玉. 压水堆核主泵流场数值模拟和空化分析[D]. 杭州:浙江大学, 2011.
RAHIM F C, RAHGOSHAY M, MOUSAVIAN S K. A study of large break LOCA in the AP1000 reactor containment[J]. Progress in nuclear energy, 2012, 54(1):132-137.