Abstract
Cold compressor (CC) was adopted to pump saturated liquid helium to obtain subcooled helium. In the Experimental Advanced Superconducting Tokamak (EAST) system, cold presses were studied and would replace the oil ring pump. The cold compressor processing and installation had been completed, and it had been tested by cold nitrogen gas. For cold compressors, testing at low temperature was essential, but the real working condition of low-temperature helium gas had great risks for large helium cryogenic system. Therefore, an independent cold nitrogen test system was an economical solution. In this work, numerical simulation and quantitative analysis method were used to investigate the flow field around different tip clearances and mass flow by CFD at liquid nitrogen temperature, and they were validated by experiments. When the tip clearance was increased by 0.1mm, the pressure ratio dropped 0.27% and the polytropic efficiency dropped 0.82%. To a certain extent, a larger tip clearance could improve the surge condition and had little influence on the efficiency. Therefore, in the design and operation, the tip clearance could be appropriately increased.
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