Local Void Fractions and Bubble Velocity in Vertical Air-Water Two-Phase Flows Measured by Needle-Contact Capacitance Probe

<table class="figure-group"><tr class="fig-image" id="a"><td><object data="https://static-preview.hindawi.com/articles/stni/volume-2018/7532618/figures/7532618.fig.0018a.svgz" name="7532618.fig.0018a" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(a) </b>Raw signal (<svg height="14.8173pt" id="M104" style="vertical-align:-5.52897pt" version="1.1" viewbox="-0.0498162 -9.28833 52.9136 14.8173" width="52.9136pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M360 -163L167 270L360 703H298L106 273V267L298 -163H360Z" id="g113-61"></path></g><g transform="matrix(.013,0,0,-0.013,5.369,0)"><path d="M219 86C216 168 211 250 206 337C201 410 189 448 163 448C131 448 79 396 43 344L60 322C91 359 110 375 118 375S132 358 136 298C141 238 152 81 155 -12H182C242 62 331 177 390 258C435 321 451 360 451 391C450 424 432 448 408 448C390 448 372 435 366 419C362 410 362 401 366 394C373 383 376 367 376 350C376 283 262 138 221 86H219Z" id="g185-40"></path></g><g transform="matrix(.0091,0,0,-0.0091,11.18,3.132)"><path d="M554 433L549 437C539 437 513 441 503 443C481 447 456 451 436 451C354 451 268 415 216 368C150 308 99 205 99 106C99 24 136 -12 165 -12C196 -12 243 14 268 33C318 70 374 118 415 181H419L395 39C374 -84 332 -149 295 -175C269 -193 245 -197 212 -197C137 -197 93 -156 76 -102C71 -87 61 -87 51 -96C36 -110 24 -130 24 -147C24 -183 76 -257 171 -257C226 -257 285 -227 323 -200C387 -155 455 -76 480 94C499 225 538 391 554 433ZM460 386C457 361 438 287 426 254C408 218 373 176 332 133C294 93 246 61 217 61C198 61 186 80 186 122C186 167 206 250 231 294C262 349 288 375 317 387C334 394 358 400 381 400C413 400 439 393 460 386Z" id="g50-104"></path></g><g transform="matrix(.013,0,0,-0.013,16.958,0)"><path d="M307 267V273L115 703H53L246 270L53 -163H115L307 267Z" id="g113-63"></path></g><g transform="matrix(.013,0,0,-0.013,25.958,0)"><path d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z" id="g117-34"></path></g><g transform="matrix(.013,0,0,-0.013,37.221,0)"><path d="M412 140C382 77 369 73 315 73H129L270 222C362 320 402 379 402 466C402 571 322 635 234 635C177 635 130 609 99 576L42 495L64 475C90 514 133 568 201 568C274 568 318 519 318 435C318 349 255 267 193 193C144 135 87 78 32 23V0H405C417 45 427 89 440 131L412 140Z" id="g113-51"></path></g><g transform="matrix(.013,0,0,-0.013,43.461,0)"><path d="M113 -12C146 -12 170 11 170 46C170 78 146 103 114 103S58 78 58 46C58 11 82 -12 113 -12Z" id="g113-47"></path></g><g transform="matrix(.013,0,0,-0.013,46.425,0)"><path d="M241 635C89 635 35 457 35 312C35 153 89 -12 240 -12C390 -12 443 166 443 312C443 466 390 635 241 635ZM238 602C329 602 354 454 354 312C354 172 330 22 240 22C152 22 124 173 124 313S148 602 238 602Z" id="g113-49"></path></g></svg> m/s, <svg height="12.5794pt" id="M105" style="vertical-align:-3.29107pt" version="1.1" viewbox="-0.0498162 -9.28833 62.6362 12.5794" width="62.6362pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M360 -163L167 270L360 703H298L106 273V267L298 -163H360Z" id="g113-61"></path></g><g transform="matrix(.013,0,0,-0.013,5.369,0)"><path d="M219 86C216 168 211 250 206 337C201 410 189 448 163 448C131 448 79 396 43 344L60 322C91 359 110 375 118 375S132 358 136 298C141 238 152 81 155 -12H182C242 62 331 177 390 258C435 321 451 360 451 391C450 424 432 448 408 448C390 448 372 435 366 419C362 410 362 401 366 394C373 383 376 367 376 350C376 283 262 138 221 86H219Z" id="g185-40"></path></g><g transform="matrix(.0091,0,0,-0.0091,11.18,3.132)"><path d="M238 675C244 702 241 710 231 710C220 710 155 682 74 673L70 643H101C147 643 151 635 142 594L39 111C18 11 36 -12 55 -12C89 -12 170 38 223 103L207 129C176 98 130 68 118 68C113 68 108 72 114 102L238 675Z" id="g50-109"></path></g><g transform="matrix(.013,0,0,-0.013,14.154,0)"><path d="M307 267V273L115 703H53L246 270L53 -163H115L307 267Z" id="g113-63"></path></g><g transform="matrix(.013,0,0,-0.013,23.154,0)"><path d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z" id="g117-34"></path></g><g transform="matrix(.013,0,0,-0.013,34.417,0)"><path d="M241 635C89 635 35 457 35 312C35 153 89 -12 240 -12C390 -12 443 166 443 312C443 466 390 635 241 635ZM238 602C329 602 354 454 354 312C354 172 330 22 240 22C152 22 124 173 124 313S148 602 238 602Z" id="g113-49"></path></g><g transform="matrix(.013,0,0,-0.013,40.657,0)"><path d="M113 -12C146 -12 170 11 170 46C170 78 146 103 114 103S58 78 58 46C58 11 82 -12 113 -12Z" id="g113-47"></path></g><g transform="matrix(.013,0,0,-0.013,43.621,0)"><path d="M241 635C89 635 35 457 35 312C35 153 89 -12 240 -12C390 -12 443 166 443 312C443 466 390 635 241 635ZM238 602C329 602 354 454 354 312C354 172 330 22 240 22C152 22 124 173 124 313S148 602 238 602Z" id="g113-49"></path></g><g transform="matrix(.013,0,0,-0.013,49.861,0)"><path d="M153 550H386L412 615L406 623H120L82 318C104 327 142 338 184 338C294 338 347 275 347 187C347 112 305 39 221 39C160 39 119 71 97 89C88 97 80 96 71 90C59 80 50 67 49 57C48 45 52 36 66 23C80 9 123 -12 169 -12C221 -11 288 15 342 59C403 109 431 165 431 225C431 308 366 395 238 395C212 395 165 379 127 364L153 550Z" id="g113-54"></path></g><g transform="matrix(.013,0,0,-0.013,56.102,0)"><path d="M153 550H386L412 615L406 623H120L82 318C104 327 142 338 184 338C294 338 347 275 347 187C347 112 305 39 221 39C160 39 119 71 97 89C88 97 80 96 71 90C59 80 50 67 49 57C48 45 52 36 66 23C80 9 123 -12 169 -12C221 -11 288 15 342 59C403 109 431 165 431 225C431 308 366 395 238 395C212 395 165 379 127 364L153 550Z" id="g113-54"></path></g></svg> m/s)</td></tr><tr class="fig-image" id="b"><td><object data="https://static-preview.hindawi.com/articles/stni/volume-2018/7532618/figures/7532618.fig.0018b.svgz" name="7532618.fig.0018b" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(b) </b>Threshold method</td></tr><tr class="fig-image" id="c"><td><object data="https://static-preview.hindawi.com/articles/stni/volume-2018/7532618/figures/7532618.fig.0018c.svgz" name="7532618.fig.0018c" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(c) </b>Slope method</td></tr><tr class="fig-image" id="d"><td><object data="https://static-preview.hindawi.com/articles/stni/volume-2018/7532618/figures/7532618.fig.0018d.svgz" name="7532618.fig.0018d" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(d) </b>Trigger-level method</td></tr><tr class="fig-image" id="e"><td><object data="https://static-preview.hindawi.com/articles/stni/volume-2018/7532618/figures/7532618.fig.0018e.svgz" name="7532618.fig.0018e" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(e) </b>Fourier transform frequency distribution (statistical method)</td></tr></table>

<div>Raw signal and data processing results.</div>

Science and Technology of Nuclear Installations

fig18

Figure 18

Figure 18: Local Void Fractions and Bubble Velocity in Vertical Air-Water Two-Phase Flows Measured by Needle-Contact Capacitance Probe 