ON MASS ENTRAINMENT BY JETS. PHASE I. PRELIMINARY INVESTIGATIONS.
ASTROMECHANICS RESEARCH DIV GIANNINI CONTROLS CORP MALVERN PA
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This report speculates on the nature of mass entrainment by free jets effluxing into a quiescent medium of equal density. The complex dynamic of the jet boundary at laminar Reynolds numbers is examined. Data has been obtained concerning the frequency of vortex shedding, vortex growth rates, and total roll-up angles. This data was obtained in a water table using pulsed hydrogen bubble generation. An estimate is made of the rate of mass entrained by the scooping-up of the surrounding fluid by the developing vortex structures. The effect of disturbances sound waves on the jet is discussed in the light of the evidence of substantial increase in the entrainment rate of an artificially excited jet. A reattaching jet experiment is proposed to measure the effect of sound on entrainment rates. Preliminary data is presented on the attachment point versus entrainment rate for a ventilated Coanda bubble at Reynolds nos. of 1060, 1380, 2790. Author
- Fluid Mechanics