Calculation of Diversion Ratio of the North Channel in the Yangtze Estuary

The circumfluence around the Jiuduan Sandbank is thoroughly studied by means of the principle of least resistance in fluid dynamics. The diversion ratio of the North Channel for 1998 is calculated, which is almost the same as the field survey data. The normal and minimum diversion ratios of the North Channel after stages I , II and III regulation works as well as the future phase are obtained. The numerical results and predicted value are accurate.

Theoretical and experimental research on influence of rotor taper on performance of cone-shape helical pumps

The structure of a rotor has full impact on the performance of cone-shaped helical pumps. Numerical simulation and experimental tests are applied to get pressure, velocity and flow of a cone-shaped helical pump, and explores flow condition of blood in artificial blood pump. Rotors with four different tapers of artificial pump are designed. The flow condition of blood at the entrance, near the front diffuser, near the rotor, near the rear diffuser and at the exit, the pressure difference between entrance and exit and flow of artificial blood pump with different taper rotors are simulated, and then the influence rules of rotor taper on the performance of cone-shaped helical pump are revealed. In order to verify the correctness of theoretical analysis, rotors with three different tapers are manufactured, physical model of artificial blood pump are built, and then the actual lift and flow of blood pump with different rotors are measured respectively. The results show that taper of rotor increases, the circumfluence of blood near the front and rear diffuser decreases, the blood flows more smoothly, the energy consumption is less, and then the guide role of blade is greater. The blood at the exit of blood pump flows along the axial direction steadily. As taper of rotor increases, the pressure difference between the entrance and exit and the flow of blood pump increase subsequently. The flow condition of blood and performance of blood pump with No.3 rotor are the best. The proposed research analyzes the influence of rotor taper on performance of blood pump quantitatively, and provides the theoretical reference for the design and improving of cone-shaped helical pump.

Throttle characteristics of multi-stage circumfluence nozzle during the separate-layer injection of CO_(2)

Separate-layer injection of CO2 is an important method to improve oil and gas production and recovery.Conventional single-stage nozzle is usually blocked by impurities,and the ice-barrier phenomenon is very common.To solve this problem,large-diameter multi-stage circumfluence nozzle was designed to release pressure stage by stage.In order to illuminate the throttle characteristics of the CO2 multi-stage circumfluence nozzles,numerical simulation was performed to test several nozzles with different diameters and stage numbers.Furthermore,we tested the throttle characteristics through laboratory experiments and obtained the effects of several critical parameters such as nozzle diameter,number of stage and pressure drop on the throttle characteristics.The results show that the flow rate decreases as the nozzle stage increases on the condition of constant pressure and nozzle diameter.And pressure difference increases as nozzle stage number increases under the constant flow rate.The throttle capability of multi-stage circumfluence nozzles was much better than the concentric nozzles.Large-diameter multi-stage nozzle is recommended rather than small-diameter single-stage nozzle during the process of separate-layer injection,which can efficiently prevent impurities and ice blocking.The results are expected to provide a theoretical support for the nozzle choice of separate-layer injection of CO2.