科创中国

Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants.More accurate models on the operating mechanism of the seals are needed to help improve their performance.The thermal fluid–solid interaction(TFSI)mechanism of the hydrostatic seal is investigated in this study.Numerical models of the flow field and seal assembly are developed.Based on the mechanism for the continuity condition of the physical quantities at the fluid–solid interface,an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method.Dynamic mesh technology is adopted to adapt to the changing boundary shape.Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure.The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data.Using the TFSI model,the behavior of the seal is presented,including mechanical and thermal deformation,and the temperature field.The influences of the rotating speed and differential pressure of the sealing device on the temperature field,which occur widely in the actual use of the seal,are studied.This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals,and the model is validated by full-sized experiments.

以重庆市为例,利用投入产出关联效应对该市的体育产业与其他产业之间的关联效应进行分析,并突出研究重庆区域物流与体育产业之间的互动关系,经验证明这种互动关系是非常强的.

Current research on the operational reliability of centrifugal pumps has mainly focused on hydrodynamic instability. However, the interaction between the fluid and structure has not been sufficiently considered; this interaction can cause vibration and dynamic stress, which can affect the reliability. In this study, the dynamic stresses in a single-blade centrifugal pump impeller are analysed under different operating conditions; the two-way coupling method is used to calculate the fluid–structure interaction. Three-dimensional unsteady Reynolds-averaged Navier-Stokes equations are solved with the SST k–ω turbulence model for the fluid in the whole flow passage, while transient structure dynamic analysis is used with the finite element method for the structure side. The dynamic stresses in the rotor system are computed according to the fourth strength theory. The stress results show that the highest stress is near the loose bearing and that the equivalent stress increases with the flow rate because the dynamic stresses are closely related to the pressure load. The stress distributions on the blade pressure side, suction side, leading edge, and trailing edge are each analysed for different flow rates; the highest stress distribution is found on the pressure side. On the blade pressure side, a relatively large stress is found near the trailing edge and hub side. Based on these results, a stress distribution prediction method is proposed for centrifugal pumps, which considers the interaction between the fluid and structure. The method can be used to check the dynamic stress at different flow rates when optimising the pump design to increase the pump reliability.

目的分离纯化链霉菌108A1776发酵液中的水溶性抗耐药结核活性成分.方法利用离子交换、反相和亲水作用等多种色谱技术进行分离纯化,通过现代波谱学方法鉴定活性成分结构.结果分离得到3个水溶性活性成分,其结构分别确定为链丝菌素EO)、N^β-乙酰链丝菌素E(2)和β-乙酰链丝菌素D(3).链丝菌素E(1)对结核分枝杆菌H37Rv和临床分离耐药株的MIC值为0.25~1.0μg/mL.结论首次利用亲水作用色谱分离纯化微生物发酵液中的水溶性活性化合物.亲水作用色谱在微生物水溶性次级代谢产物的分离纯化中具有广阔的应用前景.链丝菌素E具有较强的体外抗耐药结核分枝杆菌活性.