离心压缩机密封及空腔流动的一维/三维耦合建模研究

为了在保证数值预测精度的同时降低离心压缩机的建模复杂度,以一维密封泄漏计算替代完整的密封及空腔建模,开展了离心压缩机盖盘密封及空腔流动的源项建模方法研究。结果表明:基于源项方法的密封及空腔简化建模仅需在主流道建模基础上施加泄漏质量流量、总温和摩擦损失源项边界条件,即可较高精度地还原完整的盖盘密封及空腔建模的性能和关键流动细节。与完整建模相比,在全工况下源项建模预测的等熵效率的绝对偏差小于0.65%,总压比和等熵效率的相对性能偏差小于1%。该方法可在满足下游部件匹配设计精度需求的同时,减少50%以上的网格数量,并显著提高计算的经济性和收敛性。泄漏流量的计算精确度是影响源项建模法性能预测准确性的最关键因素,耦合建模可以采用一维计算中推荐的密封泄漏系数值。 

Research on one-dimensional/three-dimensional coupled modeling for seal and cavity flow of centrifugal compressor

In order to reduce the modeling complexity of the centrifugal compressor while ensuring the numerical prediction accuracy, a source term modeling method for the seal and cavity flow of the centrifugal compressor was studied based on the one-dimensional seal leakage calculation instead of the complete seal-cavity modeling. The results showed that the simplified seal and cavity modeling based on source term method could accurately reproduce the overall performance and key flow details obtained by calculation of full seal and cavity modeling, allowing only to impose the boundary conditions of leakage mass flow, total temperature and friction loss source term on the mainstream channel modeling. Compared with the complete modeling, the absolute deviation of the isentropic efficiency predicted by the source term modeling at full operating conditions was less than 0.65%, and the relative performance deviation of the total pressure ratio and the isentropic efficiency was less than 1%. The method could reduce the number of meshes by more than 50% while meeting the accuracy requirement of matching design for downstream components, and also significantly improve the economy and convergence of the calculation. The calculation accuracy of the leakage flow was the most critical factor affecting the accuracy of the performance prediction for the source term modeling method. The coupling modeling could adopt the recommended seal leakage coefficient value of the one-dimensional calculation.