Research On The Influencing Factors Of The Efficiency Of The Wall Effect Vacuum Generator

As an important component in pneumatic systems,vacuum ejectors have been widely used in automatic production line.At present,jet vacuum ejectors and vortex vacuum devices have become a mature technology applied to the suction of gas-impervious materials,but they are not compatible with high permeability materials.Based on the Coanda effect,the Coanda vacuum ejector is able to provide high induced flow and has unique advantages in absorbing high permeability materials.However,there are few literatures and experiments focusing on this area,this status has been an obstacle in research and application of the Coanda ejector.Therefore,to solve this problem,the research and study about influence of different factors on the performance of Coanda ejector has academic importance and practical utilization requirements.Focusing on this objective,in this thesis,much work has been made for the mathematical model of Coanda ejector and influence of different factors on the performance of it to provide the theoretical and experimental references for the research in the future.In this thesis,the theoretical model of two-dimension Coanda effect has been studied to derive the velocity expression both in laminar and turbulent flow.Combined with simulation,the gas flow condition and influence of different factors on Coanda model has been described and studied.These have become the foundation for the following work.Based on the internal flow channel of Coanda ejector,the structure of it has been designed and the ejector has been manufactured.Also,the three-dimension simulation model has been established to study distributions of internal flow and analyze influence of different factors through flow velocity inside the Coanda ejector.In order to make principle verification and obtain the influence of different factors of Coanda ejector,much verification and performance testing has been made.Also,a new indirect method to measure the rate of induced flow and primary flow,which is an important parameter of the ejector's working performance.On top of that,the vacuum response time and the air supply of Coanda ejector have been measured.The results show that its vacuum response time is about 0.2s and air supply is 450L/min.The testing of absorbing materials with different permeability has been made to verify the efficiency of Coanda ejector.The result shows that Coanda ejector can realize the suction of high permeability materials and has high efficiency.