https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&feed=atom&action=history Abstr:AC6-15 - Revision history 2024-03-28T09:48:15Z Revision history for this page on the wiki MediaWiki 1.39.2 https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36598&oldid=prev Dave.Ellacott: /* Abstract */ 2019-03-12T11:34:18Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:34, 12 March 2019</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l20">Line 20:</td> <td colspan="2" class="diff-lineno">Line 20:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>----</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>----</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{ACContribs</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{ACContribs</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|authors=A. Minakov [1,2], D. Platonov [1,2], I. Litvinov [<del style="font-weight: bold; text-decoration: none;">2</del>], S. Shtork [<del style="font-weight: bold; text-decoration: none;">2</del>], K. Hanjalić [3]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|authors=A. Minakov [1,2], D. Platonov [1,2], I. Litvinov [<ins style="font-weight: bold; text-decoration: none;">1</ins>], S. Shtork [<ins style="font-weight: bold; text-decoration: none;">1</ins>], K. Hanjalić [3]</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|organisation=</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|organisation=</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;p style=&quot;text-indent: 40px&quot;&gt;[1] Institute of Thermophysics SB RAS, Novosibirsk, Russia,&lt;/p&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;p style=&quot;text-indent: 40px&quot;&gt;[1] Institute of Thermophysics SB RAS, Novosibirsk, Russia,&lt;/p&gt;</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36581&oldid=prev Dave.Ellacott: Dave.Ellacott moved page Lib:AC6-15 to Abstr:AC6-15 2019-02-25T12:08:18Z <p>Dave.Ellacott moved page <a href="/w/index.php/Lib:AC6-15" class="mw-redirect" title="Lib:AC6-15">Lib:AC6-15</a> to <a href="/w/index.php/Abstr:AC6-15" title="Abstr:AC6-15">Abstr:AC6-15</a></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <tr class="diff-title" lang="en"> <td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:08, 25 February 2019</td> </tr><tr><td colspan="2" class="diff-notice" lang="en"><div class="mw-diff-empty">(No difference)</div> </td></tr></table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36562&oldid=prev Wolfgang.Rodi: /* Abstract */ 2019-02-01T10:56:47Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:56, 1 February 2019</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l8">Line 8:</td> <td colspan="2" class="diff-lineno">Line 8:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Application Challenge AC6-15===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Application Challenge AC6-15===</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal <del style="font-weight: bold; text-decoration: none;">flowrate</del>, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia ([[Best_Practice_Advice_AC6-15#10|Minakov&amp;nbsp;A.&amp;nbsp;''et&amp;nbsp;al.'',&amp;nbsp;2017]]).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal <ins style="font-weight: bold; text-decoration: none;">flow rate</ins>, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia ([[Best_Practice_Advice_AC6-15#10|Minakov&amp;nbsp;A.&amp;nbsp;''et&amp;nbsp;al.'',&amp;nbsp;2017]]).</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The experiments were carried out in a 60:1 scaled-down laboratory model (see [[AC6-15#figure0|figure below]]), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable ''k-&amp;epsilon;'' and ''k-&amp;omega;''-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The experiments were carried out in a 60:1 scaled-down laboratory model (see [[AC6-15#figure0|figure below]]), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable ''k-&amp;epsilon;'' and ''k-&amp;omega;''-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36450&oldid=prev Dave.Ellacott at 14:26, 22 January 2019 2019-01-22T14:26:26Z <p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:26, 22 January 2019</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l30">Line 30:</td> <td colspan="2" class="diff-lineno">Line 30:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|number=15</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|number=15</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>}}</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">© copyright ERCOFTAC 2019</ins></div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36236&oldid=prev Dave.Ellacott: /* Abstract */ 2018-11-26T12:26:00Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:26, 26 November 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l9">Line 9:</td> <td colspan="2" class="diff-lineno">Line 9:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia ([[Best_Practice_Advice_AC6-15#10|Minakov&amp;nbsp;A.&amp;nbsp;''et&amp;nbsp;al.'',&amp;nbsp;2017]]).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia ([[Best_Practice_Advice_AC6-15#10|Minakov&amp;nbsp;A.&amp;nbsp;''et&amp;nbsp;al.'',&amp;nbsp;2017]]).</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable ''k-&amp;epsilon;'' and ''k-&amp;omega;''-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The experiments were carried out in a 60:1 scaled-down laboratory model (see <ins style="font-weight: bold; text-decoration: none;">[[AC6-15#figure0|</ins>figure below<ins style="font-weight: bold; text-decoration: none;">]]</ins>), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable ''k-&amp;epsilon;'' and ''k-&amp;omega;''-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36235&oldid=prev Dave.Ellacott: /* Abstract */ 2018-11-26T12:25:04Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:25, 26 November 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l8">Line 8:</td> <td colspan="2" class="diff-lineno">Line 8:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Application Challenge AC6-15===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Application Challenge AC6-15===</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia (Minakov A. <del style="font-weight: bold; text-decoration: none;">etÿal</del>., 2017). The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable ''k-&amp;epsilon;'' and ''k-&amp;omega;''-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia (<ins style="font-weight: bold; text-decoration: none;">[[Best_Practice_Advice_AC6-15#10|</ins>Minakov<ins style="font-weight: bold; text-decoration: none;">&amp;nbsp;</ins>A.<ins style="font-weight: bold; text-decoration: none;">&amp;nbsp;''et&amp;nbsp;al</ins>.<ins style="font-weight: bold; text-decoration: none;">''</ins>,<ins style="font-weight: bold; text-decoration: none;">&amp;nbsp;</ins>2017<ins style="font-weight: bold; text-decoration: none;">]]</ins>).</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable ''k-&amp;epsilon;'' and ''k-&amp;omega;''-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36234&oldid=prev Dave.Ellacott: /* Abstract */ 2018-11-26T12:23:07Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:23, 26 November 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l8">Line 8:</td> <td colspan="2" class="diff-lineno">Line 8:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Application Challenge AC6-15===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Application Challenge AC6-15===</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=Abstract=</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia (Minakov A. etÿal., 2017). The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable k-<del style="font-weight: bold; text-decoration: none;">? </del>and k-<del style="font-weight: bold; text-decoration: none;">?</del>-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia (Minakov A. etÿal., 2017). The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable <ins style="font-weight: bold; text-decoration: none;">''</ins>k-<ins style="font-weight: bold; text-decoration: none;">&amp;epsilon;'' </ins>and <ins style="font-weight: bold; text-decoration: none;">''</ins>k-<ins style="font-weight: bold; text-decoration: none;">&amp;omega;''</ins>-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36233&oldid=prev Dave.Ellacott: /* Abstract */ 2018-11-26T12:21:39Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:21, 26 November 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l11">Line 11:</td> <td colspan="2" class="diff-lineno">Line 11:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>{|</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>{|<ins style="font-weight: bold; text-decoration: none;">align=&quot;center&quot; border=&quot;0&quot;</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|[[Image:AC6-15_figure0.png|600px]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|[[Image:AC6-15_figure0.png|600px]]</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|-</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|align="center"|Schematic view of the laboratory turbine with its draft tube and a blow-up of the swirler set</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">Schematic view of the laboratory turbine with its draft tube and a blow-up of the swirler set</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;br/&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;br/&gt;</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>----</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>----</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36232&oldid=prev Dave.Ellacott: /* Abstract */ 2018-11-26T12:20:45Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:20, 26 November 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l12">Line 12:</td> <td colspan="2" class="diff-lineno">Line 12:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{|</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{|</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|[[Image:AC6-15_figure0]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|[[Image:AC6-15_figure0<ins style="font-weight: bold; text-decoration: none;">.png|600px</ins>]]</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Schematic view of the laboratory turbine with its draft tube and a blow-up of the swirler set</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Schematic view of the laboratory turbine with its draft tube and a blow-up of the swirler set</div></td></tr> </table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=Abstr:AC6-15&diff=36230&oldid=prev Dave.Ellacott: /* Abstract */ 2018-11-26T12:18:55Z <p><span dir="auto"><span class="autocomment">Abstract</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 12:18, 26 November 2018</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l10">Line 10:</td> <td colspan="2" class="diff-lineno">Line 10:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia (Minakov A. etÿal., 2017). The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable k-? and k-?-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This test case deals with flow unsteadiness in the draft tube of a laboratory model of a Kaplan turbine operating at an off-design load with only 39% of the nominal flowrate, studied experimentally and by computational modelling and simulations in the Institute of Thermal Physics in Novosibirsk, Russia (Minakov A. etÿal., 2017). The experiments were carried out in a 60:1 scaled-down laboratory model (see figure below), in which the turbine was mimicked by a set of fixed and rotating swirlers, designed to generate the draft-tube entry flow conditions as in a real turbine. The complementing computational studies were performed using several RANS models: the realizable k-? and k-?-SST linear eddy-viscosity models (LEVM), and the basic (LRR) Reynolds-stress model (RSM), then DES (detached-eddy simulations) and LES (large-eddy simulations). The RANS and DES computations were done on numerical grids with 2 and 6 M (million) cells, and LES on 6 and 19.3M grids, the latter serving as the reference fine-grid simulations. The flow patterns, vortical structure and turbulence statistics in the turbine draft tube (DT), their effect on flow stability and pressure pulsations at a low load, appear to be governed by the conspicuous unsteady twin helix ropes. All these features are well reproduced by the LRR RANS model, DES and LES, but to a large extent remained intractable to the considered LEVMs.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">&lt;div id=&quot;figure0&quot;&gt;&lt;/div&gt;</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">{|</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|[[Image:AC6-15_figure0]]</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">|}</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Schematic view of the laboratory turbine with its draft tube and a blow-up of the swirler set</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Schematic view of the laboratory turbine with its draft tube and a blow-up of the swirler set</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> </table> Dave.Ellacott