Research On Influencing Factors Of Gas Friction Loss And Heat Exchange For Helium Blower Drive Motor In High-Temperature Gas-Cooled Reactor

High-Temperature Gas-Cooled Reactor(HTGR)has already turned out to be one of the most preferred reactor types in the nuclear power generation system of the fourth generation due to the characteristics of excellent safety,high temperature and wide application.Helium blower drive motor in high-temperature gas-cooled reactor is the only active part in the circuit of HTGR,and its normal operation has close relationship with both the safety and stability of the whole reactor.Therefore,one of the key problems which is required to be solved urgently during the development of HTGR nuclear power plants in China is having a good master of both the mechanism and law of heat exchange of the drive motor in the high-pressure helium of the total space.With the helium blower drive motor in HTGR taken as the research object,the problems studied in this dissertation include the thermal dissipation such as the flow pattern and heat transfer of helium in the working chamber,the calculation of gas friction loss in the ventilation cooling system and the influencing factors of helium on the heat transfer in the drive motor.In order to study the heat transfer process of helium blower drive motor in high-temperature gas-cooled reactor,the drive motor fluid network model of the axial/radial composite construction is established based on the fluid network theory,and then the distribution of flow and velocity at each equivalent node is obtained as well.With relevant parameters obtained from the method of fluid network as boundary conditions,accurate solution is conducted for the simplified three-dimensional fluid flow and heat transfer coupling solution model of the drive motor on the basis of the finite element method.Then,the fluid pattern of high pressure helium within the solution domain is determined,and the law of temperature distribution in each component of the drive motor is revealed.The accuracy of the boundary condition and simplified model is verified by comparing the calculation results obtained from the winding insulation temperature of stator and the results of monitoring in experiment.Based on the study of the mechanism and flow pattern obtained from helium heat transfer,detailed calculation and analysis are conducted,with regard to the gas friction loss on the stator side of the helium blower drive motor in high-temperature gas-cooled reactor.Afterwards,a calculation method for gas friction loss based on Bernoulli fluid flow equation,which can be employed to calculate total energy change,is proposed.The method takes into account the relationship between flow velocity,temperature and gas friction loss,and it is able to obtain the gas friction loss value of each ventilation duct in the ventilation cooling system on the stator side of the drive motor more accurately in comparison with the traditional analytical method.Through the comparison and analysis of the influence imposed by working environment and ventilation duct changes on gas friction loss in ventilation and cooling system,the distribution law of gas friction loss in different influencing factors is revealed.The method can be employed to carry out accurate calculation on the gas friction loss in a motor with a multi-ventilation cooling system,and offer theoretical reference to the optimization of the motor structure through the analysis on the distribution form of the gas friction loss.Based on the gas friction loss of the drive motor in high-pressure helium and the analysis of the fluid-thermal coupling,in-depth study on helium flow pattern and temperature distribution law of the main position in the drive motor such as the stator,rotor and the working chamber area,is carried out.The above-mentioned studies are carried out by taking into account the motor's demand for cooling medium and the changes of the thermal properties of helium in different environments,and the functions related to the gas friction loss of the drive motor,the heat from the fan side and the role of the heat exchange system in the working chamber are comprehensively considered.Then,the distribution laws for the temperature field of the drive motor along with the helium temperature,helium pressure and the heat input from the fan side are revealed,and thus the influencing factors of high pressure helium on the temperature distribution in the drive motor is also determined.Targeting at the structures of the drive motor,the matching relation between the ventilation cooling structure and the temperature distribution of the drive motor is studied.It was carried out by regarding the size and arrangement o f the ventilation ducts in the ventilation system as variables and comparing the temperature distribution and the peak temperatures of each component under different structural schemes.After that,the temperature distribution and the heat transfer capacity of the drive motor under different ventilation structures are studied,and the scheme of parameter optimization which can reduce the temperature rise of the motor is effectively obtained.In the meanwhile,it is also proposed that the strength of the optimized structure should be checked,when it comes to the problems of safety encountered in actual operation of the drive motor.Then,the scheme of ventilation structure design which can ensure the safe and stable operation of the motor is finally determined by analyzing the Mises equivalent stress distribution of rotor core and ventilation channel plate on the rotor side,and comparing the equivalent stress value of maximum Mises for each component under different schemes,which can accordingly provide ref erence for the improved design of the engineering prototype.