| The hovercraft propulsion fan is the main propulsion power source of the hovercraft.When the fan generates axial force,it causes disturbances in the flow field inside the fan and downstream of the fan.Among them,the magnitude of the axial force is directly related to the propulsion performance of the hovercraft,and the non-steady state characteristics of the flow field are directly related to the vibration and noise of the hovercraft.In this paper,numerical simulation is used to analyze the thrust force of the hovercraft fan and the pressure distribution characteristics of the flow field,and then analyze the influence of the surrounding structures of the fan such as the dome,engine,deck,etc.on the thrust and flow field pressure distribution of the fan.On this basis,the influence of the existence of upstream objects and downstream obstacles on the fan thrust and flow field pressure distribution is analyzed.The detailed analysis and findings are as follows:First,a comparative analysis of the influence of the deflector,engine,deck and other structures on the flow field of the fan is carried out.From the calculation results of pressure and speed,it is found that the deflector makes the air flow more concentrated,produces greater blade pressure,and has the greatest impact on the fan flow field.In this way,the numerical simulation of the fan model with only the dome and blades is carried out.Nine cross-sections are selected in the entire flow field area.Eleven monitoring points are set in each cross section along the radial direction.Monitor the radial distribution pressure of different cross-sections of the air inlet and outlet,compare and analyze the pressure distribution curve of the monitoring point,find the pressure value of each section of the air inlet and the outlet,and the distribution law of the pressure fluctuation amplitude with the radial and axial directions.Then,the pulsating pressure of each section is analyzed by fast Fourier transform.After verification,it is found that when the fan is working,the pressure value of each position in the flow field presents a pulsating situation,and as the distance from the blade is farther,the pulsating The smaller the amplitude,the analysis of the pulsation frequency identifies the main source of disturbance in the flow field as the blade.Corresponding comparative analysis was carried out on the peak and valley values of the pressure monitoring curves of each cross-section,and the change rule of the pulsation amplitude in the fan flow field along the axial and radial directions was obtained.Finally,the situation of obstacles in the upstream and downstream of the wind turbine is made.The obstacle is a cylindrical shape.Eleven different positions are selected in the upstream and downstream,and the distances from the blades is 4m,6m,8m,10m,12m,15m,20m,25m,30m,35m and 40m respectively.Three different obstacle sizes are selected at each position,that is,the diameter of the cylinder is 0.4,0.8,and 1.2 times the diameter of the fan.The influence of objects of different positions and sizes on the fan thrust and flow field pressure distribution is compared and analyzed.The hovercraft propulsion fan is the main propulsion power source of the hovercraft.When the fan generates axial force,it causes disturbances in the flow field inside the fan and downstream of the fan.Among them,the magnitude of the axial force is directly related to the propulsion performance of the hovercraft,and the non-steady state characteristics of the flow field are directly related to the vibration and noise of the hovercraft. |
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