Turbulence Measurements in a Diesel Fuel Spray using Rainbow Schlieren Deflectometry

摘要

Rainbow schlieren deflectometry (RSD) technique is used to optically quantify turbulent features of a n-heptane spray. Experiments are conducted in a constant pressure flow vessel with fuel at 100 MPA injected for 4 ms into an ambient air at various pressures and temperatures. Only the quasi-steady portion of the spray is considered and multiple injections are performed to acquire statistically significant image samples at a framing rates of 20 kHz. Schlieren images are analyzed to quantify the turbulence characteristics of fuel-air mixing in terms of liquid core length statistics, and integral length and time scales at multiple locations. These turbulence parameters and their significance are discussed to explain the overall mixing process of the spray. Results show that RSD is a powerful optical technique for turbulence measurements at engine relevant conditions.