ID 215

EFFECT OF AMBIENT PRESSURE ON THE SHEET EXITING A GAS CENTERED SWIRL COAXIAL (GCSC) INJECTOR

 

Abstract:

We report an experimental study on the near injector structure of spray exiting a Gas Centered Swirl Co-axial (GCSC) injector, where the effect of ambient pressure has been investigated. Cold flow tests were conducted with a conventional GCSC injector in an optically accessible high-pressure chamber. Water and gaseous Nitrogen were the fluids used. The parameters varied during the study were the gas Reynolds number ($0 - 46908$) and ambient pressure ($1 - 9bar$). The liquid Reynolds number was kept constant at $2275$. Spray characteristics have been analyzed at different operating conditions with the aid of high-speed visualization. Qualitative analysis shows that ambient pressure exerts a strong influence on the morphology of the annular sheet. Mean spray cone angle increases and intact sheet length decreases with increase in ambient pressure at a particular gas Reynolds number. A higher flapping of the annular sheet is observed at elevated ambient pressures. The non-intrusive method of Feature Correlation Velocimetry (FCV) has been used for quantitatively characterizing the liquid sheet at a particular spatial location. This method relies on the advection of naturally formed features/corrugations on the surface of the annular sheet for retrieving the sheet velocity. The axial and swirl velocities remain relatively unchanged at high ambient pressures. In conclusion, the sheet thickness based on axial velocity values obtained from FCV analysis remains unaltered at elevated ambient conditions.