Experimental and Numerical Study of Swirling ... - Solid Mechanics

More documents

Recommendations

Info

Experi imental and Numerical N Stud dy of Swirling g Flow in Scaveenging Processs for 2-Stroke Marin ne Diesel Engin nes Figu ure 2.9: Vorte ex Breakdown Ty ypes: (a) Bubble (b) Spiral. (Alek kseenko et al., 2007). The vortex breakdow wn is often nnot only asym dependent in nature e (Lucca-Negrro et al., 2000 high sp peed camera, conducted viisualization o Reynold ds number in the range of 110 of singl le and double e spiral breakd Sarpkay ya et al. (1995 5) to be a co speed camera. c This conical c shape high ro otational spee eds of 1000 re (2000) show s that at high h Reynolds at the center c line nev ver becomes n show th hat for high Reynolds numb celled bubble b form an nd bursts into 5 mmetric but al 0). Novak et a f vortex brea . The observvations reveal kdowns whichh previously w onical shape uusing a comp is observed ddue to rotatio ev/s. The measurements b s number of 3 x 10 negative/ rever bers the spiral o turbulence. 5 lso highly timme al. (2000) usinng kdown at higgh ed the existence was observed bby paratively lowwer ons of spirals at by Novak et aal. the meaan axial velociity rsed. Additionnally, the resullts breakdown bbypasses the twwo At high h Reynolds numbers, n a llarge three ddimensional tiime dependent instability is develope ed called as ‘PPrecessing vorttex core (PVC)’ (Yazdabadi et al., 1994 4). This is the result of the forced vortex region of the flow becominng unstable and displace ed from the ax axis of symmettry and start tto precess about the axis s (Lucca-Negr ro et al., 20000). The PVC has a regular frequency annd amplitu ude and in som me cases can caause many prooblems by locking onto othher system instabilities and a resonatingg with them (Yazdabadi eet al., 1994). AAt high Re eynolds numb bers, the vorteex breakdown is also observved to dart bacck and fort th along the axis a (Novak et al., 2000). 2.3.6 (a) (b) Helical Vortex V Structures Chapter 2 In swirl flows with filament f type vortices, the vvortex filamennt almost nevver has a straight/ rectilinear axis ddue to differrent instabilitties and wavves 24 Swirling Flows
Experi imental and Numerical N Stud dy of Swirling g Flow in Scaveenging Processs for 2-Stroke Marin ne Diesel Engin nes Figure F 2.10: Vortex Vo Filament in n a ch hamber with rota ating bo ottom (Alekseenk ko et al l., 2007). Figure 2.11 1: Streamlines (Proj ojections) in a cross-section nal plane for f a helical vort tex Filament in a tu ube (Alekseenko et al., 1999). Chapter 2 propaga ating along it (Alekseenko et al., 2007). IInstead the voortex filament is radially y displaced fro om the axis off the containerr (pipe/ cylindder in this casse) and tak kes the shape of a helix wrrapped aroundd the cylinderr axis along thhe flow. Sw wirl/ vortex flo ows exhibitingg this characteeristic are calleed ‘helical swirrl/ vortex flows’ f (Figure 2.10) (Alekseeenko et al., 20007). Helical swirl flows, like axis-symmmetric and nnon-helical asyymmetric swiirl flows, involves i the characteristicss e.g. wave ppropagation oon vortex corre, vortex breakdown and a PVC etc., that have been discusseed in previouus sections s. However, the t helical sttructure of thhe vortex corre brings moore complexity to the ov verall flow strructure and iits consequent behavior. For example in case of a helical h swirl fllow confined iin a device likke pipe/ cylindder etc., Fi igure 2.11 shows the streammlines (projecttions) when thhe vortex core is radially y displaced (fo or further posssible structurees see Alekseennko et al., 19999 & 2007 7). The conseq quent effect off cylinder walll is like a ‘miirror vortex’ i. .e. the actu ual vortex feel ls that there iis another vorrtex of identiccal properties at the sam me radial dista ance from the wall but rootating in oppposite directioon (Figure 2.12). 25 Swirling Flows
Page 1: Experimental and Numerical Study of
Page 5 and 6: Experimental and Numerical Study of
Page 23 and 24: Experi imental and Numerical N Stud
Page 43: Experimental and Numerical Study of
Page 95 and 96:
Experi imental and Numerical N Stud
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Experimental and Numerical Study of
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Manuscript J Mar Sci Technol manus
Page 247 and 248:
00000000 11111111 piston screen con
Page 249 and 250:
50 % and 75 % partially closed inta
Page 251 and 252:
V θ / V b V θ / V b V θ / V b 1.
Page 253 and 254:
V θ / V b V θ / V b V θ / V b 1.
Page 256:
DTU Mechanical Engineering Section
show all

Experimental and Numerical Study of Swirling ... - Solid Mechanics

Create successful ePaper yourself

Delete template?

Save as template?