Subsonic turbulent round and plane twin jets

Abstract

Multiple jets appear in many engineering applications such as engines of launch vehicles and aircraft, fuel injectors and other mixing devices. Twin jets are models to understand the differences from single jets that can aid the design of multiple jet configurations. This thesis is a study of two canonical configurations, round and plane twin jets. Flow are subsonic and turbulent. The study investigates the flow-field and interactions of the twin jets with different flow parameters. The investigation was carried out using a computational tool, specifically large eddy simulation (LES), which has been demonstrated to be sufficient/adequate to capture the development of such flows and scaling that depend on large scale dynamics. The LES employs explicit filtering as its subgrid scale model. Although there is a lack of authoritative and comprehensive studies of such flow interactions, especially subsonic twin round jets, in the existing literature, suitable experiments exist for twin round jets and twin plane jets for comparisons. LES of seven different flow configurations; four twin round jets and three twin plane jets were carried out. The jets emerge from round or slot nozzles normal to a wall into the ambient. The new parameter is S/d, which is the initial separation between the two jets and#119878; scaled with d, the initial diameter (round jets), or width (plane jets). In addition, LES of single round and plane jets were also performed for comparison. LES was employed to compute the unsteady flow-field evolution of the interactions between the jets. For both configurations, stationary turbulent flows were obtained, from which statistics were collected. Profiles of velocity and fluctuations, pressure, spectra and correlations were examined. Close quantitative agreement with all experiments were examined. In both flows, after merging into a single jet, profiles collapse on local scales (configuration centerline velocity and half widths)...