Design and Performance Analysis of Vacuum System in the 0.6 m Continuous Transonic Wind Tunnel

The upgrading of the vacuum system of 0.6 m continuous wind tunnel in CARDC has been completed by replacing water-ring pumps with the combination of roots and water-ring pumps, expanding the lowest operating total pressure from 20 kPa to 5 kPa. A mathematical simulation model considering pump's efficiency, pipe pressure loss and leakage rate is proposed to predict the pumping time from one pressure state to another for the wind tunnel.Resultsfrom this model are validated by experiments, and the main factors affecting the pumping time are confirmed. The results show that: the combination of roots and water-ring vacuum system is an effective way to achieve the 5 kPa total pressure in the continuous wind tunnel; the model can be used to analyze the performance of low-vacuum system considering that the deviation between model and test result is less than 10%; the average flow velocity in the pipeline should be controlled below 30 m/s and reasonable margin should be reserved for the actual pumping volume to improve operation efficiency, especially in the lowest pressure. This research can provide guidance for the design and evaluation of the vacuum system for a similar wind tunnel.