Spray characteristics of plug type swirl injector

Atomization of liquids is a complicated process. It is a common phenomenon in many industries such as aerospace, automotive, manufacturing (spray drying) and mineral processing. In swirl injectors, swirling motion is spread to the fluid due to the effect of the centrifugal force to spread out in the form of a hollow cone liquid sheet as the fluid leaves the exit orifice. Swirl injector performance and flow behavior at exit will be best understood by the efficient design and dynamics of various types of injector. Combustion chamber efficiency is based on injector performance so minor deviations from its design can significantly affect the performance. The experimental investigation of plug type swirl injector at varying injection pressure is explored in this paper. The injection pressure was varied from 0.5 bar to 4.5 bar and water was used as working fluid. The measured parameters include breakup length of liquid sheet, spray cone angle, coefficient of discharge and volume flow rate. Experimental data shows that breakup length is decreased and spray cone angle is increased with increasing injection pressure. It is also observed that volume flow rate is increased with an increase in injection pressure and the discharge coefficient is decreased with low injection pressure but if injection pressure is increased it remains nearly constant. High spray cone angle and less break up length of plug type swirl injector is important spray characteristics requirement in hybrid rocket motor combustion chamber.