消力池内双层悬栅对消能效果影响试验研究

针对在消力池内布置双层悬栅对消能效果影响鲜有研究,通过在消力池内未布置悬栅、布置单层悬栅和布置双层悬栅进行模型试验,对比分析布置悬栅前后消力池内流态、最大水深以及消能率。结果表明:在设计流量Q为15 L/s时,布置双层悬栅后,消力池内流态更加稳定,最大水深下降更加明显,但改变悬栅布置型式和栅条数,消能率变化不大。     

悬栅布置形式对消力池消能效果的影响试验

悬栅消能工是将栅条悬空布置于泄水陡坡或消力池内的一种新型消能方式,为进一步研究新型悬栅消能工及其消能效果,通过物理模型对影响消力池消能效果的矩形悬栅布置形式进行试验。结果表明:消力池内布置悬栅对稳定水流和降低水深作用明显;由栅高hs、栅距bs、悬栅数量ns对池内最大水深hm影响得出栅高hs的适宜值为10 cm,栅距bs的适宜值为4~5 cm,悬栅数量ns的适宜值为16~20根;在Q=15 L/s下,悬栅hs=10 cm、bs=4 cm、ns=20根的布置形式可将消力池最大水深降低4.97 cm,降幅高达15.84%。     

某水电站泄水陡坡体型优化模型试验研究

根据工程建设的需要对某泄水陡坡进行水工模型试验,验证其总体布置和建筑物结构布置的合理性,分析原设计体型存在的主要问题,对泄水陡坡体型进行优化,且在消力池内设置了消能悬栅,并进行体型优化试验。试验表明,优化后的泄水陡坡过流能力满足要求,消力池内悬栅的设置,改善了消力池内的水流流态,工程总体布置和建筑物结构布置合理。     

基于均匀正交设计的消力池内双层悬栅布置优化试验

由于在消力池内布置双层悬栅对消能效果影响少有研究,考虑到单宽流量、悬栅栅条数、栅距和层距等影响因素,采用均匀正交设计,考察4因素3水平,选择UL9(34)优化方案进行模型试验,对比了不同流量和悬栅布置型式组合下消力池内下降水深及消能率。试验结果表明:不考虑单宽流量时,消力池内布置双层悬栅,下降水深受层距、栅条数以及栅距影响较大,其中层距改变影响最大,消能率受这些影响因素影响较小;单宽流量较小时,层距和栅距均与下降水深成正比关系,单宽流量较大时,层距与下降水深成正比关系。     

隧洞洞内新型消能试验研究

本文通过试验研究,分析悬栅消力池的消能特性,加栅前后消力池的消能率、消力池内水深及消力池下游明流洞内涌浪的变化.     

悬栅消能工均匀正交设计及投影寻踪回归试验研究

为探讨消力池内悬栅消能工试验设计和研究方法,在设计流量Q=8.0 L/s条件下,对悬栅消能工最大水深的3个影响因子栅高hs、栅距bs、数量ns运用均匀正交试验设计,并用投影寻踪回归方法对试验数据结果进行PPR建模分析及计算机仿真优化,得到池内最大水深影响因子的排序是悬栅数量ns、栅距bs和栅高hs;当池内最大水深达优值18.233 cm时,影响因子的优化组合为栅高hs=9 cm、栅距bs=5 cm和ns=16。     

低弗劳德数梯形墩-悬栅消力池水力特性

针对大单宽流量、低弗劳德数消力池内消能问题,通过物理模型试验方法,对比分析消力池内加设梯形墩和悬栅消能工后水力特性和消能效果,优化梯形墩-悬栅消力池布置形式。结果表明：在低弗劳德数水流条件下,梯形墩-悬栅联合消能工断面水深分布均匀,消力池底板沿程压力分布梯度和时均压力分布系数波动幅度较小,整体稳定性较优;动能修正系数基本保持在1<α<2的范围内,可有效改善入池断面流速分布;消能率由传统消力池的52.25%、70.37%、75.89%分别提升至56.74%、75.95%、79.22%;梯形墩-悬栅消力池内悬栅单排等间距、高度与尾坎同高布置时,梯形墩呈双排交错形式布置在距池首0.35L左右处对于整体流态改善明显,消力池出口流速可降至0.4 m/s,消能率提高至59.63%、76.12%、79.37%,研究结果可为同类工程的底流消能问题提供一种新思路。     

底流消力池墩栅联合消能工水力特性数值模拟研究

针对低弗汝德数底流消力池消能不充分、流态紊乱及底板时均动水压强过大而造成失稳破坏的问题,通过采用数值模拟的方法,对传统消力池内分别加设趾墩-悬栅、消力墩-悬栅、T型墩-悬栅联合辅助消能工,分析各联合辅助消能工的水力特性及消能规律。结果表明：消力池内布置3种墩栅联合辅助消能工后,相较于传统消力池,水面流态趋于平稳,消力池底板最大时均动水压强分别减小了50%、25%、12.5%,消能率分别提高了3.13%、6.06%、5.24%;相较于同种墩型消力池（未加悬栅）,消力池底板最大时均动水压强分别减小了20%、25%、12.5%,消能率分别提高了0.17%、3.05%、0.39%;趾墩、消力墩、T型墩与悬栅辅助消能工联合运用具有优势叠加效应。本研究可为解决同类底流消能问题提供参考。     

趾墩-悬栅消力池水力特性分析

为了解决新疆某工程泄洪洞消力池流态紊乱、消能率低的问题,采用数值模拟方法 ,在设计及校核流量下,对传统消力池、悬栅消力池以及趾墩-悬栅消力池3种不同形式消力池水力特性进行系统性分析。结果表明：趾墩-悬栅联合消能工改善了消力池内水流流态,消力池发生淹没式水跃,其池内悬栅与悬栅间隙处涡量分布广泛,池内整体涡量分布比悬栅消力池分布更加均匀。在设计流量下,消能率为74.41%,相较于传统消力池消能率提高2.61%,相较于悬栅消力池消能率提高0.95%;在校核流量下,消能率为78.99%,相较于传统消力池消能率提高5.64%,相较于悬栅消力池消能率提高0.95%。     

双层悬栅消力池的水力特性数值模拟

针对物理模型试验难以得到详细的流速、压强等水力参数数据问题,利用流体力学软件FLUENT建立RNG k-ε双方程紊流模型进行数值模拟,得到消力池内最大水深、流态、流速以及压强等水力参数,通过数学模型计算值与物理模型试验值对比分析以及数值模拟计算值之间对比分析,结果表明:数学模型计算值与物理模型试验值吻合较好,且布置双层悬栅时,计算值与试验值误差较小;双层悬栅使水流产生漩涡的能力较强,从而使水流对护坦冲击较小,护坦处涌浪降低,对压强变化影响较大,说明双层悬栅具有更好的消波稳流作用。     

阶梯溢流坝和宽尾墩及消力池组合消能的水流数值模拟研究

采用两相流模型,辅以Realizable k湍流模型,来模拟阶梯溢流坝和消力池组合以及阶梯溢流坝、宽尾墩和消力池组合两种联合消能工的水力特性,获得了流速场、压强场、紊动动能及紊动动能耗散率等物理参量的分布。网格划分采用了分区域划分:模型中任何形状不规则的复杂部分采用非结构网格划分,对形状规则的部分则采用了结构网格划分,并根据流动梯度的大小安排网格的疏密程度。采用有限体积法对控制方程进行离散。采用了VOF法处理自由水面,使用PISO算法求解速度与压力的耦连方程组。比较分析了两种消能工在速度场、压强场、紊动动能及紊动动能耗散率的差异。研究结果表明:受宽尾墩的影响,坝面及消力池中的流速均小于无宽尾墩的情况,而台阶坝面的压强明显高于无宽尾墩的情况;在消力池中紊动动能及其耗散率均大于无宽尾墩的情况。可见,阶梯溢流坝、宽尾墩和消力池组合消能工的消能优于无宽尾墩的情况。     

热分层流动计算中若干差分格式的比较

本文应用常规的守恒方程及湍流模型，对二维池内热分层流动建立了数学模型，并在Ｐａｔａｎｋａｒ的压力校正法基础上对该数学模型进行了数值计算，计算中的差分格式为乘方格式、一阶迎风、二阶迎风和ＱＵＩＣＫ。通过与实验的比较分析，建议计算应采用ＱＵＩＣＫ格式，并在进行风格独立性试验的基础上使用加密网络。     

Numerical research on flow and thermal transport in cooling pool of electrical power station using three depth-averaged turbulence models

This paper describes a numerical simulation of thermal discharge in the cooling pool of an electrical power station, aiming to develop general-purpose computational programs for grid generation and flow/pollutant transport in the complex domains of natural and artificial waterways. Three depth-averaged two-equation closure turbulence models, k - ε , k - w , and k - ω , were used to close the quasi three-dimensional hydrodynamic model. The k -ω model was recently established by the authors and is still in th...     

非对接分区结构网格中的数值计算方法

利用有限体积方法在非正交网格系统中建立了非对接分区结构网格数值求解模型,给出了分区结构风格交界面的数据结构形式及数值计算方法,采用SIMPLE算法编制了计算程序;对后台阶绕流进行二分区流场计算,并与实验结果比较,具有很好的一致性;同时对无限流场中和非对称平板间的圆柱绕流进行了分区计算。结果表明,本文建立的分区交界面数值计算模型是可靠的,可用于处理几何形状复杂的流场模拟。     

APPLICATION OF A MODIFIED QUICK SCHEME TO DEPTHAVERAGED k-( TURBULENCE MODEL BASED ON UNSTRUCTURED GRIDS

The modified QUICK scheme on unstructured grid was used to improve the advection flux approximation, and the depth-averaged turbulence model with the scheme based on FVM by SIMPLE series algorithm was established and applied to spur-dike flow computation. In this model, the over-relaxed approach was adopted to estimate the diffusion flux in view of its advantages in reducing errors and sustaining numerical stability usually encountered in non-orthogonal meshes. Two spur-dike cases with different defection angles (90oand 135o) were analyzed to validate the model. Computed results show that the predicted velocities and recirculation lengths are in good agreement with the observed data. Moreover, the computations on structured and unstructured grids were compared in terms of the approximately equivalent grid numbers. It can be concluded that the precision with unstructured grids is higher than that with structured grids in spite that the CPU time required is slightly more with unstructured grids. Thus, it is significant to apply the method to numerical simulation of practical hydraulic engineering.     

SIMULATION OF SEDIMENT-LADEN FLOW BY DEPTH-AVERAGED MODEL BASED ON UNSTRUCTURED COLLOCATED GRID

The 2-D depth-averaged mathematical model for sediment-laden flows has been widely used in river control and other related engineering problems, and now it is usually solved on structured grids. Since the natural river is usually very complicated in plane boundary, and unstructured grids are more attractive in solving the problems with complicated domains, the following questions about solving 2-D depth-averaged model were discussed in this article: (1) a modified Bowyer algorithm was suggested to generate unstructured grids for natural rivers, (2) the Finite Volume Method (FVM) is employed to discretize the governing equations of the 2-D depth-averaged model and an implicit scheme was suggested with unstructured collocated grids, (3) the observed hydrological data of the Chenglingji Reach in the Yangtze River are used for verification of the presented method. It seems that the suggested numerical scheme works very well, and the simulation results of both hydraulic characteristics and river bed deformation are in good agreement with the observed ones.     

长江口北支基于混合网格的通量差分裂水流水质计算模式

本文建立了基于三角形四边形混合网格的二维水流水质耦合数值计算模式。网格通过推进阵面法自动生成，控制方程采用有限体积法对守恒变量进行离散，应用通量差分裂格式(FDS)计算边界上的水量、动量和污染物法向数值通量。模型应用于长江口北支崇海公路大桥修建后的流场浓度场的数值模拟。网格根据工程实际需要分区布置．在工程外区域采用有结构的四边形网格布置，既可贴合实际岸线边界，又便于组织数据结构；在工程附近区域采用无结构的三角形网格布置，利用三角形网格的灵活性实现复杂地形边界和局部小尺度流场浓度场的精细模拟。模型计算出的流场和浓度场与实测值对比令人满意，较好地解决了复杂边界和工程网格尺度问题。     

基于多重网格的地表水文与二维水动力动态双向耦合模型研究

针对流域洪涝模拟模型的计算精度、格式稳定性及计算效率等问题,本文提出基于多重网格技术的地表水文与二维水动力动态双向耦合模型(M-DBCM)。地表水文模型采用非线性水库法模拟降雨产流和径流;二维水动力模型采用浅水方程模拟洪水演进过程。采用不同分辨率的网格划分计算区域,在粗网格区域采用地表水文模型模拟降雨径流过程;在细网格区域采用二维水动力模型模拟洪涝积水区的水流运动。地表水文和二维水动力模型通过内部耦合移动界面(Coupling Moving Interface, CMI)实现无缝连接,保证通过CMI的水量和动量等通量守恒,提高模型的模拟精度。采用时间显式格式同时求解地表水文和水动力模型,在不同区域采用不同的计算时间步长,以提高模型的计算效率。通过典型案例验证本文构建的耦合模型的性能,结果表明本文提出的动态双向耦合模型能够在保证模拟精度的同时提高计算效率。     

农网降损措施的探讨

线损率是供电企业一项重要的经济技术指标,农网线损的管理是供电企业一项重要而复杂的管理工作。分析了造成农网严重电损的主要原因,提出应以民为本,以提高供电质量为主要目标,坚持科学规划、适度超前的原则,加强农网改造;采用三相接户线,提高农网降损的效率。     

APPLICATION OF A MODIFIED QUICK SCHEME TO DEPTH- AVERAGED κ-ε TURBULENCE MODEL BASED ON UNSTRUCTURED GRIDS

The modified QUICK scheme on unstructured grid was used to improve the advection flux approximation, and the depth-averaged κ-ε turbulence model with the scheme based on FVM by SIMPLE series algorithm was established and applied to spur-dike flow computation. In this model, the over-relaxed approach was adopted to estimate the diffusion flux in view of its advantages in reducing errors and sustaining numerical stability usually encountered in non-orthogonal meshes. Two spur-dike cases with different defection angles （90°and 135°） were analyzed to validate the model. Computed results show that the predicted velocities and recirculation lengths are in good agreement with the observed data. Moreover, the computations on structured and unstructured grids were compared in terms of the approximately equivalent grid numbers. It can be concluded that the precision with unstructured grids is higher than that with structured grids in spite that the CPU time required is slightly more with unstructured grids Thus, it is significant to apply the method to numerical simulation of practical hydraulic engineering.