叶片进口几何形状对核主泵空化流动特性的影响

Effect of blade inlet geometry on cavitation flow characteristics of nuclear main pump

为研究叶片进口几何形状对核主泵水力性能以及空化性能的影响,基于连续性方程、雷诺时均N-S方程和RNG k-ε湍流模型,对4种不同叶片进口几何形状的核主泵模型泵进行全流场空化模拟,得出不同叶片进口几何形状对核主泵外特性以及空化性能的影响规律.结果表明:叶片进口边减薄,使叶片进口对流体的排挤作用减弱,改善了叶片对进口流动条件改变的适应性,减小了叶片进口处的流动损失,提高了效率.另外,增大叶片进口边圆角,进口减薄程度加剧,使进口处过流断面面积增大,流速降低,进而导致压力增大,且低压区逐渐向叶片出口移动,在发生空化时,气泡对叶片进口相对流动角影响逐渐变小.同时,随着叶片进口减薄程度的加剧,叶片进口更加接近流线型,液体绕流叶片头部时产生冲击减小,使叶片吸力面前盖板处最低压力有所增大.

In order to study the effect of blade inlet geometry on hydraulic performance and cavitation performance of nuclear main pump, a cavitational simulation of full flow field in the model of nuclear main pump with 4 kinds of blade inlet geometry is carried out based on the continuity equation, Reynolds time-average equation and RNG k-ε turbulence mode, to get the rule of influence of blade inlet geometry on the external characteristics and cavitation performance of the pump. The result shows that the blade inlet edge thinning will make the push-squeeze action of blade inlet on incoming flow weakened, so that the adaptability of blade to the change of the inlet flow condition will be improved, the flow loss at blade inlet reduced, and the efficiency increased. In addition, increasing the fillet of blade inlet edge and intensifying the blade inlet edge thinning degree will make the cross-section area of the blade inlet increased, the velocity reduced, the pressure increased and the low pressure zone to move gradually towards the blade outlet, so that when cavitation occurs, the effect of bubbles on relative flow angle at blade inlet will become smaller. At the same time, with the aggravation of blade inlet edge thinning degree, blade inlet edge will be closer to a streamline and the impact of liquid flow on blade head will be reduced, making the minimum pressure on blade suction surface at front shroud increased to some extent.