Researches Of Similitude Theory For Axial Flow Helium Compressor

HTGR (High Temperature Gas-cooled Reactor) with the advantage of simplicity, safety, reliability and low cost is the fourth generation of reactor type. It consists of reactor unit and power conversion unit. The performance of the helium compressor in the PCU is the determined factor which influences the efficiency of the generation of electricity. The HTGR use a direct Helium Brayton cycle for the power conversion. In this configuration, there is a strong coupling between the compressor and the other elements of the system. The estimation of compressor performances in stable and transient operations is of high importance for the designer. Besides this the experimental work during the design and manufacture of helium compressor involve consumption of helium, high cost of construction of experimental system. Considering these influence factors, it is necessary to use air to fulfill such task, and the researches of similitude theory for axial flow helium compressor is highlighted.The first stage of high-pressured section is set as a model in this study, the similitude theory and how it applies to the experiment is studied. The parameters for helium compressor is as following: axial velocity of the helium compressor is≤200m/s, helium flowrate is 4.72kg/s, the inlet pressure is 1.0253×10~6Pa, and inlet temperature is 35.5℃. The key problem in the simulation in such cases is the determination of setting similitude criterion. On the basis of similitude theory study, the similitude criterion is set up by methods of determining physical parameters, differential equation method, and dimensional analysis method. After comparison of the similitude criterion derived from above methods, S_r,Re,Euare choosen as similitude criterion for helium compressor. As for selection of the simulation method, the traditional simulation method, the method based on our study and the ASME PTC-10 experimental method are compared in detail. The conclusion is that ASME PTC-10 method is not valid in such case. The simulation method from single stage to multistage is mentioned simultaneously.The traditional simulation scheme, new simulation scheme are verified for the sample helium compressor by using the NUMECA software, and the flow mechanism along the blade was analyzed. It can be included that: With the Ma number less great than 0.37, the aerodynamic behavior was less influence by this number, normally can be ignored, with reaction great than 0.5, by adding positive revolve in advance can remain the high efficiency of the compressor. CFD result of above simulation schemes show that the new imulation scheme based on the criterion of equal Sr,Re,Eu suits the designed parameter of the first stage of helium compressor well.In order to get experimental data for the designer, an experimental system is built according to the design scheme of HTGR-10 helium axial compressor. Under different operating pressures, the compressor experimenta data are obtained for both Helium and air, the performance map of helium axial compressor was abtained by numerical simulation for the first time, and verified by the experimental data. From the comparision between the different simulation schemes with the experimental result, the new simulation scheme super to the other schemes and the results show that the simulation is effective and ready for the practical usage. This study solves the problem of how to set the simulation parameters in the design of helium axial compressor with air. Since the requirement of large power for the whole turbine system of helium can not be accomplished at present, it also offers a theoretical basis for the experimentalstudy of whole turbine system of helium.