On the Inner Jet Spread Angles of Coaxial Jets from Subcritical to Supercritical Conditions with Preliminary Numerical Results
Abstract
A study is performed to analyze the behavior of the inner jet spread angles in a coaxial jet flow configuration similar to those used in liquid rocket engines. These angles are measured from back-lit images. Data is presented for sub-, near-, and supercritical non-reactive N2 coaxial jets. In the subcritical regime, the effects of an externally-imposed transverse acoustic field are also analyzed. The acoustic field is generated using two piezo-sirens and driven at a frequency of 3.0 - 0.1 kHz. Pressure oscillations vary from 16 to 22 kPa, peak to peak, at the location of the jet with background pressure of 1.5 MPa. For all cases, by varying the inner and outer jet temperatures and mass flowrates, outer to inner jet velocity ratios from 0.25 to 23 and outer to inner jet momentum flux ratios (J) from 0.02 to 23 are achieved. In the case where no acoustic excitation is applied the angles for the near- and supercritical cases show more spread compared to their subcritical counterparts for 1.0<J<2.5, attaining values up to 18-deg. However, at higher J values, the spread angles for subcritical pressures are larger than those for near- and supercritical pressures. When acoustics are applied at subcritical pressures, the largest spread angles occur for 2<J<10, reaching values as high as 38-deg. Also, preliminary numerical results are presented for two supercritical cases with only one acoustic source present.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 23, 2008
- Accession Number
- ADA502385
Entities
People
- Douglas G. Talley
- Hsin-yuan Lyu
- Ivett Leyva
- Jeffrey J. Graham
- Juan I. Rodriguez
Organizations
- Air Force Research Laboratory