Raman Scattering Measurements of Gaseous Ethylene Jets in Mach 2 Supersonic Crossflow

The structures of sonic ethylene jets delivered from orifices of three different diameters and two injection angles (30 and 90 deg) into a Mach 2 supersonic crossflow were studied experimentally. The ratio of the cross-sectional areas of the largest and smallest injectors is 25:1. Time-averaged spontaneous vibrational Raman scattering was used to quantify injectant concentrations by constructing two-dimensional spanwise concentration images from the one-dimensional linewise Raman scattering images. Based on the present data set, new penetration height correlations were developed to treat cases with injection angles of both 30 and 90 deg. Excluding the influence of wall boundary layer, the present measurements show that the properties of fuel plume structures, such as shape, size, and concentration profiles, are scalable with the injector size. The measured ethylene concentrations were also compared with predictions from the revised jet penetration code, which was calibrated primarily with hydrogen and helium. Discrepancies were observed between the measurements and the jet penetration code predictions for the structures of ethylene fuel plumes. The experimental data generated from the present study can be used to validate the numerical simulations.