A STUDY ON THE ATOMIZATION AND SPRAY CHARACTERISTICS OF GELLED SIMULANTS FORMED BY TWO IMPINGING JETS

Open Access
Author:
Fakhri, Syed Abdul Khader
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Richard A Yetter, Thesis Advisor
  • Jongguen Lee, Thesis Advisor
Keywords:
  • GHP
  • Hypergolic
  • Proplellants
  • Gelled Hypergolic Propellants
  • Atomization
  • Spray
  • Nozzle
  • Sheet
  • Simulant
  • Nozzle Jet
Abstract:
The atomization mechanism of Gelled Hypergolic Propellants (GHPs) in an impinging jet flow field is significantly different from that of non-gelled liquid propellants and is not clearly understood. In this study, rheologically matched non-Newtonian fluids which are non-reactive and non-toxic were used to act as a simulants for the gelled hypergolic propellants. A Newtonian fluid has been used as a simulant for liquid propellants and to act as a comparison standard for the non-Newtonian simulants. This study explored the effect of nozzle geometry such as orifice inlet shape and aspect ratio on the jet stream surface dynamics and the break up process before and after doublet jet impingement, respectively. Gels produced, using polymer or particle gellants, displayed less disturbed surfaces than non-gelled fluids, due to increased viscosity. As a result, for a given flow rate the sheet formed by impinging jets was much more stable and the sheet break up length was greater for gelled-water than non-gelled water jets. The nozzle aspect ratio has more noticeable effects on the near-field jet stream characteristics for both fluids than the orifice inlet shape. The longer nozzles form a more stable jet stream which delays the break-up of the sheet, leading to greater break up lengths than the shorter nozzles. For similar Reynolds number, droplet size for gelled water is much smaller than that for non-gelled water. Also, impinging jets employing gelled water produce sprays which are distributed over a wider space and in a wider range of droplet sizes than the jets with non-gelled water.