| This research is based on the axial annular wall surface flowing liquid film of the pintle injector.Simplify it into a semi-free annular liquid film flowing on the outer surface of the cylinder.Through numerical simulation and high-speed photography experiments,the effects of different structural parameters on the flow field,liquid film flow characteristics and surface wave characteristics of the liquid film were studied.It provides a reference for the in-depth study of liquid film flow and the application of liquid film.Firstly,the variation law of the flow field in the liquid film generator was obtained through simulation,and a new model was designed.It is found that cavitation is a dynamic development process.Increasing the outlet angle,back pressure,or reducing the pressure drop can suppress cavitation.The cavitation and the outlet angle of the flow channel are key factors affecting the velocity distribution of the flow field.High-speed thin liquid film can be obtained at large outlet angle.Secondly,for the new model,the flow characteristics of the liquid film were simulated and compared by high-speed photography experiments.It is found that the thickness of the liquid film gradually increases along the path,and the speed gradually decreases.Wall resistance and surface wave of liquid film are the fundamental factors that affect the development of liquid film speed and thickness under different working conditions.And found that the change in liquid film speed is the direct cause of the change in thickness。Finally,through the processing and analysis of the images obtained by high-speed photography,the surface wave and fracture characteristics of the liquid film are obtained.It is found that the fluctuations on the surface of the liquid film are no periodic and disorderly complex fluctuations.As the axial position increases and the pressure drop increases,the degree of liquid film fluctuation becomes larger.As the width of the gap increases,the degree of liquid film fluctuation decreases first and then increases.There is a critical wave steepness of 0.25 and a critical relative wave height of 0.30.It was found that the scale change of the wave and whether the wave is fully developed have an important influence on the fluctuation law of the liquid film. |
