不同网孔与筒体模型对Y型网式过滤器性能的影响

Y型网式过滤器广泛运用于微灌系统,其良好的水力性能是保证微灌系统稳定运行的关键,为了分析其水力性能,该研究采用数值模拟和物理试验相结合的方法,分析了网式过滤器在3种滤网网孔（正方形、圆形、菱形）以及3种筒体弧线角度（0°、15°、30°）下,过滤器内压降系数、滤芯网面流量分布、内部流场、压力分布等水力特性的变化。结果表明：物理试验与数值模拟之间的水头损失系数平均差异为9%,表明了数值模拟的可靠性,其中圆形网孔过滤器水头损失系数最大,正方形次之,菱形最小;滤网网孔形状对过滤器网面过流量分布的影响较大,正方形网孔过滤器的中速过流量区域占比最高达到了47.5%,圆形次之,菱形最小仅为26.5%。过滤器的水头损失随着筒体弧线角度的增加而逐渐减小,35°的压降系数较0°的减小了73.15%,网面流量的分布也随着角度的增加变得更为均匀,其中35°的中速过流量区域面积较0°增大了71.48%,水力性能明显提高;此外随着筒体弧线角度的增加,出口侧中上段滤网处的内外压差明显减小。因此在实际微灌系统中,选择网孔为正方形、筒体弧线角度30°的过滤器,其内部流场缓和、网面流量分布均匀,提高了过滤器的水力性能和使用寿命。该研究成果可为网式过滤器结构优化提供设计方案与理论依据。     

参窝水库溢流坝闸墩裂缝加固处理效果分析

参窝水库运行以来,溢流坝闸墩出现竖向活动裂缝,危及结构安全,提出适宜的修补加固技术,并对修补加固处理后的结构采用ANSYS软件进行受力状态有限元计算分析,得出闸墩混凝土裂缝修补加固后安全可靠,裂缝不再继续扩展,工程可安全运行,继续发挥其效益。     

Differential mixing action effects on functional properties and polymeric protein size distribution of wheat dough

A micro Z-arm mixer and a 2g-Mixograph were used to compare the effect of pin and Z-arm-type mixing actions on mixing properties of wheat flour dough. Although the two mixing curves obtained with pin- and Z-arm-type mixing action showed a very similar mixing trace, no significant correlation was found between the two mixers other than the number of revolutions required for optimal dough consistency (peak resistance). Mixing requirement was described by a rate-independent parameter, the number of revolutions to peak dough development and was found to be greater in a Z-arm mixer than in a pin mixer. Mixing requirement showed significant correlation with stability, which is therefore a dough strength parameter. The change in the polymeric structure of gluten proteins of dough as indicated by %UPP (unextractable polymeric protein percentage) was monitored and showed a smaller decrease with Z-arm mixing than with pin mixing. Therefore, pin-mixing action is more energetic than Z-arm mixing. At peak resistance, Z-arm mixing gives a larger quantity of polymeric protein content in the dough relative to pin mixing. The degree of dough development at maximum resistance in the different mixers was shown to be different. A new parameter, delta-_UPPMZ${\mathrm{UPP}}_{\mathrm{MZ}}$ (the difference between %UPP of dough obtained with pin vs Z-arm mixing actions) was identified and proposed to have some relationship to the stability of the polymeric proteins in the dough.     

Gauging weirs impede the upstream migration of adult river lamprey Lampetra fluviatilis

Abstract The ability of individual and groups of 30 migrating adult river lamprey Lampetra fluviatilis L. to pass a Crump or flat‐v gauging weir under two discharge regimes (moderate and low) was assessed in an experimental channel. Despite repeated attempts by the lamprey, the Crump weir remained impassable during all trials. Lamprey passage over the flat‐v weir occurred only during group trials at low discharge (5.73 ± 0.19 L s^?1) and only as a single burst swimming event via the deeper water passing over the centre of the weir. Lampreys generally approached the weirs along the channel walls and particularly favoured the true right wall associated with elevated velocities during low discharge and reverse currents at moderate discharge (68.06 ± 2.41 L s^?1). Time spent immediately below the weir was lower than expected compared with further downstream. Rate of weir approach, attempts to pass (absolute number and as a proportion of the total approaches) and time spent immediately downstream of the weir were highest for the Crump weir at low discharge and the flat‐v weir at moderate discharge. The present study suggests that gauging weirs may severely impede the movements of migrating adult river lamprey under low to moderate discharges.     

两相流分离鳃与浑水水力分离清水装置的集成试验研究

将两相流分离鳃与浑水水力分离清水装置(以下简称装置)进行集成试验研究.研究表明,把分离鳃沿径向悬挂在装置柱体中后,装置在溢流清水浊度相同的情况下,溢流流量增加了1.5～2.0倍.而且分离鳃的数量对其溢流也有一定的影响,随着分离鳃数量的增加,溢流相同浊度清水的流量也随之增加.     

水工模型试验中薄壁堰缩尺效应分析

缩尺效应是影响水工模型试验精度的重要因素之一。本文通过矩形薄壁堰试验，验证了缩尺效应的存在，分析了缩尺效应对矩形薄壁堰泄水能力的影响，推荐了计算精度较高的计算公式，提出了减小缩尺效应的措施及建议。     

高堰式双螺旋分级机螺旋轴组焊新工艺的研究

以2FG12高堰式双螺旋分级机为例,介绍螺旋轴组焊制造新工艺,在保证产品质量要求的前提下,用在空心轴上氧割三条槽,并在槽上焊装螺母来调整圆跳动再分段焊接的工艺方案,替代细长轴装配焊接的传统制作工艺,解决了传统工艺制造中存在的同轴度要求高、圆跳动大、制造困难的问题.     

自然和人工模拟降雨条件下紫色土坡地的磷素迁移

采用人工降雨和自然降雨的方法对紫色土坡地磷素迁移进行比较研究。研究结果表明：紫色土坡地产生地表径流和壤中流两种径流模式，壤中流其径流动态过程受降雨强度和表层作物覆盖度的影响；持续性变化的大雨强更容易引起土壤磷非点源输出，导致水体富营养化；在中到暴雨条件下，壤中流累积迁移流量低于地表径流，差幅决定于土壤表层界面（植被覆盖）特征，地表径流中的磷迁移量是壤中流迁移的3～4倍。     

三维无压渗流分析的溢出面迭代法及其应用

全面考虑三维无压渗流问题中溢出面上的边界条件，将渗流自由面的确定问题转化为确定溢出面，同时结合使用渗透矩阵调整方法和丢单元技巧，给出了三维无压渗流问题的溢出面迭代方法。算例和工程应用表明该方法有效可行，而且具有较高的计算精度，最大误差为2．06％。     

混合堰的设计与应用技术研究

小型过水建筑物的堰型，因各种原因需要，可分段设计成两种或两种以上的混合堰型。提出了两种混合堰计算流量的方法，并通过水工模型试验及原型观测进行了验证，可供同类型工程参考。