Investigation on the Impact of Divergent Corrugated Lobe Length on Supersonic Flow

A numerical study on supersonic flow from convergent–divergent (CD) lobed nozzles without corrugation (0%) and with corrugation of 30, 60, and 90% of the diverging section was performed. The study maintained the following parameters to be identical, viz., exit area, lobe count, throat diameter, length of the convergent region, length of the divergent region, and nozzle pressure ratio (NPR). The predictions were compared with experimental values of the conical CD nozzle for NPR 3.7 and 5. The study revealed that varying the corrugation lobe lengths led to changes in the structure of jet flow and shock waves. Initially, a “double-diamond” shock pattern was observed in the corrugated CD lobed nozzle, which merged into a single-diamond shock pattern downstream. Additionally, decreasing corrugation lobe length led to higher dissipation rates. However, shorter corrugation lengths resulted in a higher diverging cone angle, leading to flow separation. Thus, the 60% corrugation length is optimal for achieving a higher mixing rate. These findings provide valuable insights into the flow dynamics of supersonic nozzles and highlight the impact of corrugation lobe length on jet behavior.