Experimentelle Untersuchung der Kontrolle subsonischer und sonic Strahlen mit gefinnten Stabs

The influence of various tab geometry on subsonic and sonic jet mixing control is examined. The tabs, strategically installed at the nozzle exit with the obstruction within 5%, alter the jet flow field. The tab geometries employed include stem-alone, top, and bottom finned stem tabs. The stem alone tab resembles a plain rectangular tab. Finned stem tabs indicate fins configured on the stem tab. The study investigates the effect of fins location on the stem alone tab in mixing of axisymmetric subsonic and sonic jets. The total pressure measurements and the shadowgraph visualization techniques were utilized to estimate the efficacy of the stem-alone tab as well as the top and bottom finned stem tab. Measurements of the total pressure were made in the subsonic and sonic jet flow fields. At the highly underexpanded sonic jet condition with a pressure ratio of 4, the shadowgraph visualization is performed. The measurement of potential core length and the investigation of jet decay is done using axial pressure measurements. The potential core length of stem and finned stem tab-controlled jets was lower than that of uncontrolled jets. The top and bottom finned stem tab controlled sonic jet results in the greatest core length reduction of 78%. Additionally, the tab-controlled jet decays at a faster rate than the uncontrolled jet. The bottom finned stem tab-controlled jet had the highest rate of decay among the tab-controlled jets. The spreading characteristics of the uncontrolled and tab-controlled jets are investigated using radial pressure profiles. The bottom finned stem tab controlled jet achieves the greater spread rate. The differences in the shock cell structures parallel and perpendicular to the stem tab directions were visible in the shadowgraph images taken at highly under expanded sonic jet condition. Furthermore, the bottom finned stem tab produced the comparatively weakest waves, which is advantageous from an aeroacoustics perspective, and the tab insertion produced weaker waves in the jet field. The visualization results align with the data from the pressure profile.