Shock Wave Characteristics of Twin-Supersonic Jet Interaction in a Confined Duct

This study investigates the evolution of shock structures during the interaction of two rectangular parallel underexpanded jets in a confined duct. A comparison of shock structures during the interaction of twin jets in confined as well as with open boundaries were also investigated. An experimental study has been conducted in which a primary straight duct is opened into a suddenly expanding section forming a backward facing step (BFS) on the top and bottom sides of the duct outlet. A secondary underexpanded jet is issued, parallel to the primary jet, from the top BFS wall. The two supersonic jet interacts and merges, forming a single jet, which sticks to the nearest duct wall due to the Coanda effect. Optical flow visualization using the time-resolved shadowgraph method has been performed to investigate the evolution of shock reflection characteristics. Two interaction shocks are formed when the jets interact, which terminates at the triple point of the Mach reflections formed in the primary and secondary jet. The reflected shock waves from the Mach reflection of primary and secondary jet interacts with each other forming an Edney Type-V kind of reflection.