Accession Number:

ADA409828

Title:

Raman Scattering Measurement in the Initial Region of Sub- and Supercritical Jets

Descriptive Note:

Technical paper

Corporate Author:

ENERGY RESEARCH CONSULTANTS INC LAGUNA HILLS CA

Report Date:

2000-07-19

Pagination or Media Count:

12.0

Abstract:

A high-pressure chamber is used to investigate and further enhance our knowledge and physical understanding on effects of thermodynamical subcritical-to-supercritical transition of ambient condition on cryogenic liquid injection using two-dimensional scattering. Pure liquid N2 is injected into N2. The injector is a 508-micron diameter straight hole having a long length-to-diameter ratio of 100. The optical setup uses a pulsed NdYag laser frequency-doubled to 532 nm. Difficulties arise with optical breakdown of the N2 molecules in drops and ligaments by local focusing of the laser beam dominating the Raman signal particularly at sub- and near-critical regions. The severity of this problem is reduced by stretching the laser pulse width using a double-loop design with mirrors and beam splitters. Careful and painstaking alignment is needed to take advantage of this pulse-stretcher design. Two-dimensional images are taken near the injector and results interpreted in terms of density plots. At subcritical ambient conditions a small number of images are needed for averaging and strong Raman signal is obtained.

Subject Categories:

  • Fluid Mechanics
  • Combustion and Ignition
  • Liquid Propellant Rocket Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE