CFD Jet Wake thermal characteristics of heated turbulent jets in cross flow.pdf
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JET-WAKE THERMAL TURBULENT s . A. Sherif Assistant Professor Member AIAA Department of Mechanical Engineering University of Miami Coral Gables Florida 33124 Abstract jets The This paper is one in a series reporting on discharging to cross-flowing water streams. experiments were carried out in the 0.6 1 m x 1.067 m semi-closed circuit water channel at Iowa State Universit y. Hot water was injected vertically up- ward from a circular pipe located near the channel bottom to simulate the turbulent heated jet. Con - tours of mean and RMS temperatures both across and along the jet are reported up to late~al nd downstream distances of 1.15 and 37 jet diameters, respectively, and for velocity ratios of 1. 2, 4 , and 7. The contours were used to explain the com- plex interaction mechanism between the free stream and the jet in both the jet and wake region s. Nomenclature jet diameter at discharge jet- to-f ree stream velocity ratio, Uj /U m mean temperature fluctuati ng temperature jet disc harge temperature free stream temperature jet dis charge veloci ty free st ream velocity streamwise distance transverse (spanwise) distance vertical distance Introduction In most practical situations jets and plumes are either discharged vertically or at an angle to a cross flow. This is the case in exhaust gases dis- charging into the atmosphere, condenser cooling water pouring into rivers, and the jet in the V/STOL aircraft. The words jet and plume are sometimes used in- terchangeably. A plume is in general a free shear flow in which the primary source of kinetic energy and momentum flux arises through body forces. In a jet the kinetic energy and momentum are large at discharge, having been imparted to the flow by a pressure drop through an orifice , nozzle, or tube. A forced plume or a buoyant jet are flows whose motion is in transition from a jet to a plume (Rodi) l Experimental work on the behavior of plumes in flowing ambients is numerous. Bryant and cowdrey2 studied the trajectory of heated gir plumes in a wind tunnel. Slawson and Csanady conducted ex- periments to determine the mean path of buoyant bent -over chimney plumes. l4alitsky4 visualize smoke plumes with a single camera. Hewett et al. CHARACTERISTICS OF HEATED JETS IN CROSS FLOW R. H. Pletcher rrofessor Member AIAA Department of ~echanical ngineering Ioba State University Ams Iowa SO 11 and ~ewett~ tudied smokesta ck plumes in a statle atmosphere. ~rin~felt~ easured plume rise at in- dustrial chimneys. The same problem was also studied by Leavtbt et akl, Carpenter et al. and Th om as et al .. We il and ~ a r i l l a ' ' inj ect ed ferric chloride into a water towing tank in order to model a plume in a laminar cross flow. Barilla varied the initial angle of the issuing plume and the bending angle of the discharge nozzle for dif- ferent Reynolds numbers and observed that far downstream of the discharge nozzle the plume rise is independent of the orientation of the discharge. Experiments on round turbulent nonbuoyant jets where the main thrust was on velocity an d/o r tur - bulence i ensity measurements w re conducted by .JordinsonJr, ~ha~~ov,~~ ordier ~effer I6 Kef fer and ain es, gfatte,18 Pratte and Ba nes. Gerend atrick. P1 ten and Keffer, ar- ' ' Bergeles et al. lt Storms elb and Mar- gas0'6127 in Crowe and Rieseb eter :28 Chassaing et al. : and Chan and Kennedy. 5 Experiments on round turbulent buoyant jets in which the main thrust was on velocity, concentra- tion, temperature or tr ectory measurements carried gut by Fan l 1 br ham ant7Eysink. Abraham. ~urner adot . 3b Ayoub, Cavola. and Cavola and Davis. 9 Experiments on round turbulent heated nonbuoyant jets in which the main thrust was on trajectory. velocity, temperature, or penetration measur e were carried out by 4yll aghan and Ruggeri, P i Callaghan and Bowden, Ruggeri Ruggeri Campbet$ and Schetz, ~chetz,~~ amsey, Ra sey and Goldstein, Kamotani and Greber. 1,53 ' Experiments on turbulent nonbuoyant jets in which the main thrust was on studying the structure of the jet wake , jet cross-secti on, vortex shedding in the jet, or measuring the vorticity in the jet or wa e were arried out Chang-Lu and Hsiu- Chen," Rous e. " McAll ister Pratte a d ~ e f fer, McMahon et a1. 57 F a d Weston,' ~cston,~~ ~oussa,~~ nd Moussa et al. Experiments on round turbulent nonbuoyant jets in which the main thrust was on ments were carried out by Vogle bury6pd Wooler et al. d5 H Lett and Mi ler, McMah n and Mosher. 67 Mosher Wu et a1. Mikolowsky 8 and Mikolowsky and McMahon. Measurements on round or plane, heated or un- heated, turbulent jets in which the main emphasis was on studying the turbulence structure in terms of Reynolds stresses, turbulent heat flux, higher-orde r ments, were carried out by Crabb, Crabb t 11. " Andreopoulos 74*75 Andreopoulos and 7 8 Rodi. 78, tmap rian and lIa ni u. j7 and She rif and Pl et- cher Although the measurements reported in the literature seem to be numerous, few studies went Copyright @ 1988 by S. A. Sherif. Published by the American Institute of Aeronautics and Astronautics. Inc. with permission.
