Air induction nozzles possess good anti-drift performance,the throat and orifice sizes of the nozzles are the main design parameters that affecting atomization.Therefore,Venturi tube nozzles and conventional flat fan ...Air induction nozzles possess good anti-drift performance,the throat and orifice sizes of the nozzles are the main design parameters that affecting atomization.Therefore,Venturi tube nozzles and conventional flat fan nozzles were assembled together to investigate the flow rate,droplet size,the quantity of air in droplets affected by a single design parameter of nozzles with applying high speed camera and Spraytec laser diffraction system.The results showed that:the flow rate of the air induction nozzle depended only on the throat size of Venturi tube and pressure,and it was proportional to the throat size of Venturi tube at the same pressure;The flat fan nozzle’s orifice size and Venturi tube size significantly affected volume median diameter of droplets,which generally increased after adding surfactant;A new model was established after optimizing classical equation for calculating the percentage of intake air in droplets and studying the effects of throat and orifice size of air induction nozzles on spray characteristics.By variance analysis,it was verified that the new model of quantity of air in droplets produced by all connected nozzles was correct.The calculation showed that the bubbles sizes ranged at 200-900μm and were in proportion to the droplet size with the percentage of intake air of 10%to 90%.Contrast to the change of volume median diameter and droplet velocity,the existence of intake air could influence their change degree to some extent.展开更多
A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bu...A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bubble lubrication technique utilizes the negative pressure region above the upper surface of the hydrofoil as the ship moves forward to drive air to the skin of the hull. In the present study, the reduction rate of the drag by applying the WAIP device is numerically investigated with the open source toolbox OpenFOAM. The generated air layer and the bubbles are observed. The numerical results indicate that the reduction rate of the drag closely depends on the depth of the submergence of the hydrofoil, the angle of attack of the hydrofoil, and the pressure in the air inlet. It is also proportional to the air flow rate. The underlying physics of the fluid dynamics is explored.展开更多
基金supported by National Key Research and Development Program(No.2016YFD0200706)Heilongjiang Bayi Agricultural University Academic Achievement Introduction Project(No.XDB2013-08)+1 种基金Natural Science Outstanding Youth Project of Heilongjiang Province of China(No.YQ2019E032)University Level Key Project of Heilongjiang Bayi Agricultural University(No.XA2015-01).
文摘Air induction nozzles possess good anti-drift performance,the throat and orifice sizes of the nozzles are the main design parameters that affecting atomization.Therefore,Venturi tube nozzles and conventional flat fan nozzles were assembled together to investigate the flow rate,droplet size,the quantity of air in droplets affected by a single design parameter of nozzles with applying high speed camera and Spraytec laser diffraction system.The results showed that:the flow rate of the air induction nozzle depended only on the throat size of Venturi tube and pressure,and it was proportional to the throat size of Venturi tube at the same pressure;The flat fan nozzle’s orifice size and Venturi tube size significantly affected volume median diameter of droplets,which generally increased after adding surfactant;A new model was established after optimizing classical equation for calculating the percentage of intake air in droplets and studying the effects of throat and orifice size of air induction nozzles on spray characteristics.By variance analysis,it was verified that the new model of quantity of air in droplets produced by all connected nozzles was correct.The calculation showed that the bubbles sizes ranged at 200-900μm and were in proportion to the droplet size with the percentage of intake air of 10%to 90%.Contrast to the change of volume median diameter and droplet velocity,the existence of intake air could influence their change degree to some extent.
基金Project supported by the National Natural Science Youth Foundation of China(Grant No.11902125).
文摘A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bubble lubrication technique utilizes the negative pressure region above the upper surface of the hydrofoil as the ship moves forward to drive air to the skin of the hull. In the present study, the reduction rate of the drag by applying the WAIP device is numerically investigated with the open source toolbox OpenFOAM. The generated air layer and the bubbles are observed. The numerical results indicate that the reduction rate of the drag closely depends on the depth of the submergence of the hydrofoil, the angle of attack of the hydrofoil, and the pressure in the air inlet. It is also proportional to the air flow rate. The underlying physics of the fluid dynamics is explored.
