Theoretical analysis for dynamic characteristics of liquid swirl injector

The dynamic models of liquid swirl injector were established with the linearized method and the transfer matrix models of swirl injector were deduced for linking with other components to study the functions of swirl injector in the rocket engine dynamic system.The validity of the open swirl injector dynamic model was confirmed by the test data from the reference.The calculation results show that,under the same pressure drop and size,the amplitude of outlet flow rate oscillation of the open swirl injector is much less than the classical swirl injector,but the lagging phase angle is larger.As the injector interacts with its feeding pipe-line,the resonance frequency of outlet flow rate pulsation is determined by the acoustics characteristics of the feeding system,but the resonance peak amplitude is defined by the characteristics of the swirl injector.If the injection pressure drop is increased,the amplitude of the flow oscillation at the outlet must be reduced.In the case of keeping the injector pressure drop in the same level,higher engine system pressure may aggravate the oscillation amplitude of the flow rate at the outlet.