某水库溢洪道方形消力竖井优化研究
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摘要
某水库工程侧槽式溢洪道方形消力竖井水工模型试验表明,由于竖井断面尺寸和深度较小,宣泄校核洪水时部分水流直接冲击泄洪洞段进口底板,造成洞进口段流态恶劣。宣泄校核洪水时竖井段各测点的计算空化数介于0. 13～0. 82之间,井壁处个别位置的空化数略小于初生空化数,可能产生空蚀。设计洪水和校核洪水时消能竖井消能率约为53%。应用RNG k-ε模型并结合VOF方法通过系列数值模拟试验对消力井的设计方案进行修改优化,提出了增加消力井深度至8 m、方井宽度增加至8 m的方案,其余尺寸不变。数值模拟数据表明,消力井的尺寸满足设计和校核洪水的安全泄流要求,校核流量工况消能率达到65. 55%,消力井最大负压相对于原方案降低了约为50%,最小空化数由原方案的0. 13提高到了0. 38。
The hydraulic model test of the square-shaped stilling shaft of a side channel spillway of a reservoir project showed that part of the water flow directly impacted the inlet floor of the flood discharge tunnel section during the flood discharge check due to the small size and depth of the shaft section,which resulted in poor flow in the inlet section of the tunnel. The calculated cavitation numbers of each measuring point in the shaft section during the venting of the nuclear flood were between 0. 13 and 0. 82. The cavitation number at the individual position of the well wall was slightly smaller than the initial cavitation number,which may cause cavitation. The energy dissipation rate of the energy dissipation shaft during design floods and check floods was approximately 53%. The RNG k-ε model combining with the VOF method was used to modify and optimize the design of the stilling well through a series of numerical simulation experiments. The scheme of increasing the depth of the well to 8 m and the square well width to 8 m was proposed,whereas the remaining dimensionsdid not change. The numerical simulation showed that the sizes of the stilling well meet the safety discharge requirements of design and check flood,the energy dissipation rate of the checked flow condition reached 65. 55%,and the maximum negative pressure of the stilling well reduced about 50% compared with the original scheme. The minimum cavitation number of the original scheme 0. 13 increased to 0. 38.
The hydraulic model test of the square-shaped stilling shaft of a side channel spillway of a reservoir project showed that part of the water flow directly impacted the inlet floor of the flood discharge tunnel section during the flood discharge check due to the small size and depth of the shaft section,which resulted in poor flow in the inlet section of the tunnel. The calculated cavitation numbers of each measuring point in the shaft section during the venting of the nuclear flood were between 0. 13 and 0. 82. The cavitation number at the individual position of the well wall was slightly smaller than the initial cavitation number,which may cause cavitation. The energy dissipation rate of the energy dissipation shaft during design floods and check floods was approximately 53%. The RNG k-ε model combining with the VOF method was used to modify and optimize the design of the stilling well through a series of numerical simulation experiments. The scheme of increasing the depth of the well to 8 m and the square well width to 8 m was proposed,whereas the remaining dimensionsdid not change. The numerical simulation showed that the sizes of the stilling well meet the safety discharge requirements of design and check flood,the energy dissipation rate of the checked flow condition reached 65. 55%,and the maximum negative pressure of the stilling well reduced about 50% compared with the original scheme. The minimum cavitation number of the original scheme 0. 13 increased to 0. 38.
引文
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[10]李炜.水力计算手册[M].北京:中国水利水电出版社,2006.
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[15]YAKHOT V,ORSZAG S A. Renormalization group analysis of turbulence. I. Basic theory[J]. Journal of Scientific Computing,1986,1(1):3-51.
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