Effect of Lip Thickness on Under-expanded Coaxial Sonic Jet Mixing

A detailed numerical analysis was carried out to study the behaviour of an under-expanded coaxial jet at nozzle pressure ratio of 3. The primary nozzle exit lip thickness considered in this study was 0.7mm, 2.65mm and 4.9mm. Centreline pressure decay, Mach contour and density contour were examined to understand the under-expanded coaxial jet characteristics. The findings demonstrated that the mixing of lip 4.9mm is superior when compared to the other lip thicknesses. The study also found that the core length reduces as the lip thickness is increased. The result also reveals that the shock crossover in the primary core of the under-expanded coaxial jet is strongly influenced by the nozzle lip thickness.