Study On Atomization Characteristics Of High-pressure Jet And Pulsed Jet In Supersonic Flow

The injection atomization characteristics of transverse liquid high-pressure jet and pulse jet into mach 2.1 cold supersonic crossflow were investigated by experiments and numerical simulation.The effects of pulse frequency,injection pressure and nozzle diameter on the injection atomization characteristics of transverse liquid jet and distribution of droplet motion were analyzed.Pulse jet frequency was adjusted by controlling opening and closing time of the valve for transverse liquid low-pulse jet into mach 2.1 cold supersonic crossflow.The optical measurements such as high speed photography,shadowgraphy were employed to study transient jet structures,jet dynamic characteristics and pennetration depth under different conditions.The results show: jet pennetration depth oscillation frequency is equal to characteristic frequency of injection pressure.The pressure pulsation could effectively increase jet penetration depth.Jet penetration depth could be increased by reducing the pulse width of the jet and increasing the jet pulse frequency.With jet injection pressure increasing,response time of the penetration depth reaching peak point become smaller.Mechanical flow pulsation device which were designed by our project team were made use of to adjust the pulse frequency to study high pulse jet into mach 2.1 cold supersonic crossflow.The results show: penetration depth curve of high pulse jet is lower than low pulse jet.Besides,penetration depth and pulse frequency is not linear relationship.The increase of nozzle diameter is good to jet penetration depth curves significantly uplift.High-pressure experimental platform including BOSCH manual high-pressure pump,BOSCH electrical pulse nozzle,nozzle control device and high-pressure pipeline were builded to study transverse liquid high-pressure jet into mach 2.1 cold supersonic crossflow.The results were obtained by experimental analysis and DPM model simulation: With jet injection pressure rising,jet penetration depth and its growth rate tend to increase.With jet injection pressure rising,atomizing area amd air flow area which exist in high injection pressure jet become larger,liquid droplet size become smaller.With the increase of nozzle diameter,penetration depth and lateral extension area increase obviously and jet atomizing effect enhanced.It could be obtained that high-pressure jet penetration depth formula correction coefficient is small and the power value of momentum flux ratio is large which is twice of the power value of the low pressure jet momentum flux ratio values.