CHARACTERIZATION OF IMPINGING DIESEL SPRAYS WITH A REDUCED-ORDER MODEL AND GAS JET EXPERIMENTS

Open Access
Author:
Ruth, Daniel Johnson
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Jacqueline Antonia O'connor, Thesis Supervisor
Keywords:
  • combustion
  • diesel
  • sprays
  • impingement
  • mixing
  • gas jets
Abstract:
The mixing of a diesel spray with in-cylinder gases is driven by both turbulent mixing during the free-jet penetration phase and by mixing during its impingement on surfaces such as the piston bowl. Current reduced order models, and many experiments, focus solely on the free-jet penetration phase, although jet-wall interaction occurs during a significant portion of the duration of a fuel injection in both small-bore and large-bore engines. A control volume-based model for the spreading of an impinging spray along a flat wall is presented as a first step towards capturing key jet processes during the impingement phase of fuel injection. Schlieren measurements of impinging gaseous jets are used to evaluate the model, and a strategy of accounting for the varying density in gas jet injections is introduced. The model, coupled with the free jet model of Musculus and Kattke, is shown to predict published impinging diesel data as well. The model is then used to compare global entrainment effects at various diesel conditions, providing a means for evaluating the effects of combustion parameters on entrainment with more realistic engine geometries. Finally, mixing phenomena relating to advanced combustion techniques, including rate-shaping and the use of multiple injections, are investigated with the model.