Experimental observations have shown that precessing jets have two distinct flow regimes. At "subcritical" Strouhal numbers, the jet continues to move away from the axis of precession. At "supercritical" Strouhal numbers, the jet bends back towards the axis of precession and eventually appears axisymmetric downstream. The objective of this study is to numerically determine the critical Strouhal number for the transition between the two flow regimes and to observe the nature of a precessing jet. A three-dimensional Navier Stokes solver employing the artificial compressibility method and a four-stage Runge-Kutta scheme has been used. Two Reynolds numbers, 125 and 250 were considered. The precessing jet was found to have a pressure gradient acting across it which caused it to spiral and bend back towards the axis of precession. The critical Strouhal number was independent of the Reynolds number and determined to be ∼ 5×10-3. This conclusion compared favorably with experimental observations at high Reynolds numbers.
|Original language||English (US)|
|Number of pages||8|
|Journal||American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED|
|State||Published - Dec 1 1996|
All Science Journal Classification (ASJC) codes