梯形琴键堰泄流能力影响因素及其敏感性研究

The Piano Key Weirs (PKW) have the advantages of great discharge capacity and less occupied space. Compared with the traditional sharp-crested weir and ogee-crested weir, the Piano Key Weirs can improve discharge capacity manifoldly. Conventional rectangular key weir has been extensively studied. However, trapezoidal key weir which has greater discharge capacity obtained only few related research results. In this project, the method of model experiment is adopted to study the flow field characteristics of trapezoidal piano key weirs and to distinguish characteristics of free outflow, critical outflow and submerged outflow quantitatively. By studying the response relationship between drainage efficiency of trapezoidal Piano Key Weirs and the upstream head, the internal law of the action is revealed and bad flow patterns generated under different working conditions are summarized. Through series of multi-group model tests, the sensitivity of related parameters which affect trapezoidal piano key weir flow coefficient, including geometric parameters and flow conditions etc. is studied. By studying these parameters, we can extract the influence factors with the most significant effects thus reveal the action mechanism of single influence factor. Combine the experimental data and hydraulics theory, to establish the flow calculation method of trapezoidal key weirs. Identify the high efficiency areas of discharge coefficient curve based on the engineering quantity, structural safety and bad flow patterns in order to propose other multi-objective coupled trapezoidal key weir design method to provide the trapezoidal piano key weir construction with technical support.

琴键堰有泄流能力强、占用空间少的优势，和薄壁堰、实用堰相比，琴键堰能成倍地提高溢洪道的泄流能力。常规的矩形琴键堰已得到了广泛的研究，而梯形琴键堰作为一种拥有更强泄流能力的堰型却鲜有相关研究成果。本项目拟采用模型实验的方法，精细地研究梯形琴键堰运行时的流场特性，明确量化区分自由出流、临界出流和淹没出流三种特征流态的指标，研究梯形琴键堰泄流效率与上游水头变化之间的响应关系，阐明其内在作用规律，并归纳不同工况下产生的不良流态；通过多组次的系列模型试验对影响梯形琴键堰流量系数的相关参数进行敏感性研究，包括几何参数以及来流条件，提炼出起显著作用的影响因子，并揭示单个影响因子的作用机理；结合系列实验数据和水力学理论，建立梯形琴键堰的流量计算方法；基于工程量、结构安全和不良流态等因素甄别流量系数曲线的高效区域，提出多目标耦合的梯形琴键堰的设计方法。从而为梯形琴键堰的建造与应用提供技术支撑。

琴键堰有泄流能力强、占用空间少的优势，和薄壁堰、实用堰相比，琴键堰能成倍地提高溢洪道的泄流能力。常规的矩形琴键堰已得到了广泛的研究，而梯形琴键堰作为一种拥有更强泄流能力的堰型却鲜有相关研究成果。.本项目采用模型实验的方法，精细地研究了梯形琴键堰运行时的流场特性，明确量化区分自由出流、过渡出流和淹没出流三种特征流态的指标，研究了梯形琴键堰泄流效率与上游水头变化之间的响应关系，阐明了其内在作用规律，并归纳了不同工况下产生的不良流态；通过多组次的系列模型试验对影响梯形琴键堰流量系数的相关参数进行了敏感性研究，包括几何参数以及来流条件，提炼出了起显著作用的影响因子，并揭示了单个影响因子的作用机理；结合系列试验数据和水力学理论，建立了梯形琴键堰的流量计算方法；基于工程量、结构安全和不良流态等因素甄别流量系数曲线的高效区域，提出了多目标耦合的梯形琴键堰的设计方法。从而为梯形琴键堰的建造与应用提供了技术支撑。