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Hospital ward is one of non-negligible potential places to occur cross-infection among patients and health workers. Air-borne transmission was regarded as the main infection route of the SARS-CoV-2. Preventing the air-borne transmission should be a significant measure, which could effectively mitigate the risk of the virus infection. Based on those consideration, in this study, the influence of different types of air distribution on ventilation effectiveness was modeled through Computational Fluid Dynamics (CFD) simulations. Several typical negative pressure wards same as the ward in Wuhan Thunder God Mountain hospital and conformed to the Chinese National Health Commission (NHC) guidelines were modelled. We simulated the influence of different locations of air supply inlets, analysed the influence of the buffer door and compared the contaminant concentration on different entry route for health workers. The results show that the air distribution required by NHC guidelines could retain a directional airflow from the bed-zone to the toilet, which also has a better accessibility of supply air, and health workers are safer to avoid standing closed to the air exhaust outlet in the downstream area of pollutants during ward rounds.

Most of the research on the cavitation with entrained air has focused on the military direction, but it ,about centrifugal pumps, which is relevant to people's livelihood, is still relatively lacking. In order to study the basic law of the development of cavitation inside centrifugal pumps under aeration conditions, a test bench suitable for cavitation experiments with incoming flow containing gas was obtained. Furthermore, a single-stage single-suction 6-blade centrifugal pump was used as the research object to conduct pressure pulsation experiments under cavitation condition when the incoming flow was 1.0% air viod fraction at 2900r/min-50m3/h. The results showed that: After cavitation happened, the greater aeration content will deteriorate the pump's anti-cavitation performance, but the head curve is more gentle in falling down compared to natural cavitation. Hence aeration has a beneficial effect on the performance degradation of the pump under the cavitation condition. At the same time, before the cavitation number drops to the fracture cavitation number of the pump, aeration has improvement in the efficiency of the pump in different degrees , especially in the situation with the ventilated rate of 1.0%. The main frequency of pressure pulsation at the inlet and outlet of the test pump after aeration is dominated by the blade frequency. The shaft frequency signal at the outlet gradually decreases with the cavitation number lessened. Moreover the amplitude of the blade frequency grows slightly with the reduction of the cavitation number. But it tends to soar when the cavitation number is less than the fracture cavitation number.