Mixture Formation in a Spray Observed by Spontaneous Raman Spectroscopy

Diesel-like fuels (n-heptane and heptamethylnonane) were injected into a high pressure (45 bar) and high temperature (500 °C) chamber. Spontaneous Raman spectroscopy allowed the determination of fuel-air ratios at different times after injection and at several locations inside the spray. Nearly 100,000 single point measurements were evaluated to investigate space and time dependence of the mixture. Different steps of mixture formation in the propagating spray could be recognized.