Penetration and Mixing of Fully Modulated Turbulent Jets in Crossflow

摘要: Fully-modulated, incompressible, turbulent transverse jets were studied experimentally over a range of pulsing frequencies, duty-cycles, and at two jet-to-crossflow velocity ratios. The jet flow was completely modulated by operating solenoid valve resulting in the shut off supply during portion cycle. planar laserinduced fluorescence technique used to determine penetration, dilution, structural features pulsed jets. molecular mixing rate quantified through chemical reaction between crossflow fluids. Short injection times resulted creation vortex ring structures whereas long produced axially elongated puffs, similar segment steady jet. latter case only modest enhancement penetration depth dilution. Pulsed dominated had depths significantly greater than with same ratio. Penetration up about 5 value 50 diameters downstream exit observed 200 ms pulses. Duty-cycle significant effect on performance short times. Increasing duty-cycle for fixed time diminished penetration. dilution rates also increased greatest reduction approximately 50% well-separated pulses