核主泵前腔间隙对性能影响的数值计算

Numerical calculation of influence of gap between impeller shroud and diffuser side wall on performance of reactor coolant pump

基于相对坐标系下的雷诺时均N-S方程和RNG k-ε湍流模型,采用SIMPLE算法,以清水为介质,对AP1000核主泵模型进行数值模拟.通过改变压水室与前腔间隙设计出4种不同方案,并对各种方案下泵内流动进行全三维数值模拟,获得不同间隙下模型泵轴向力和前腔内流动变化趋势和规律.计算结果表明:在工作流量(0.8Qd^1.2Qd)下,间隙变化对泵扬程和效率都有一定影响;核主泵前腔间隙变化导致泵最高效率点位置相对于设计工况发生偏移,其偏移方向和偏移程度与间隙变化无明显对应关系;在设计工况(1.0Qd)下,泵效率在间隙为0.6 mm时高于其他间隙,相比间隙为1.8 mm时提高了1.66%;在1.2Qd工况下,间隙为1.8 mm时效率高于其他间隙,相比间隙为2.4 mm时泵效率提高了2.17%;从全工况看,间隙对轴向力影响较小,轴向力随着流量的增大呈单调递减趋势,其计算值明显低于试验值,但随着流量的增加,理论计算值的相对误差有减小趋势.

The numerical simulations of flow of water in AP1000 reactor coolant pump model are per- formed based on the Reynolds averaged N - S equations and RNG κ-ε turbulence model by using SIMPLE algorithm. Firstly, the size of the gap between the impeller shroud and the diffuser side wall is designed with four values. Secondly, the flow field in the pumps with these sizes are simulated. Final- ly, the axial thrust and flow structures in the gap and collector are obtained and discussed under va- rious gap sizes. The results show that the gap size has a certain impact on the pump head and efficien- cy in a range of 0.8Qd - 1.2Qd flow rate. The change in gap size cause a shift of best efficiency point from the design point, but the shift scale and direction do not correlate with the gap size evidently. Un- der the design condition, the pump efficiency at 0. 6 mm gap is better than at the others, and increased by 1.66% compared with 1.8ram gap. Under 1.2Q,d flow condition, the pump is more efficient at 1.8 mm gap than at other gaps, and the pump efficiency is improved by 2.17% compared with 2.4 mm gap. Under all working conditions, the gap size has less i^ff/uenee on the axial thrust which shows a monotonic decreasing trend as the flow rate increases. The analytical axial thrust is much lower than the tested va- lue obviously. With increasing flow rate, the anMyticM axial thrust approaches the measurement.