| Popis: |
The structures of ethylene jets injected from orifices of three different diameters at 30 and 90 degrees 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. Raman scattering was used to quantify injectant concentrations in the fuel plumes. The measured ethylene concentrations were compared with the predictions from the revised JETPEN code, which was mainly calibrated with H2 and He gases. Discrepancies were observed between the measurements and the JETPEN predictions for the structures of ethylene fuel plumes. Generally, JETPEN under-predicts the fuel plume size for ethylene jets injected at 90 degrees. The under-prediction worsens at large x/d locations and especially at high jet-to- air momentum flux ratio conditions. The JETPEN code slightly over-predicts the fuel plume size for the 30° jets. For a given injection condition, the predicted fuel plume for the 30° jet is larger than that for the 90° jet, which is not borne out by the experimental observation. Despite the discrepancies between predicted and observed fuel plume structures, the fuel plume penetration heights predicted by the JETPEN code agree well with the measured penetration heights. 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. Based on the present data set, new penetration height correlations were developed to treat cases with injection angles other than 90 degrees. The experimental data generated from the present study can be used to validate the numerical simulations. NOMENCLATURE |
