阶梯水流的水力与绕流特性
发布时间：2019-06-06 06:37
【摘要】：在地下空间的大规模建设开发、城市极端降水事件频繁发生情况下,地下空间遭受水侵风险极高,地下空间水侵灾害事件已不容忽视。地下空间出入口阶梯是泛滥河水或暴雨积水入侵时被困人员撤离的关键通道,已成为威胁行人安全撤离的风险极高的区域。为了探讨地下空间水侵灾害时被困人员疏散时的安全性,本文针对性地研究了水侵灾害时用于行人行走的阶梯上水流的水力特性及人体(简化为柱体)的绕流特性,主要内容如下： 首先,总结了阶梯掺气水流的类型和水流掺气的原因,将掺气水流划分为含清水层的掺气水流和不含清水层的掺气水流,分析了掺气水流的运动规律,归纳了不同数量水气交界面的掺气水流的掺气运动机理,并根据水流掺气的相关理论,推导出了两个气相线(面)源(两个水气交界面)掺气浓度分布的基本形式及水力特性参数的计算方法。 其次,根据选定的地下空间出入口形态及水力学模型试验原理,设计制作出带中间休息平台的地下空间出入口阶梯综合试验平台,试验研究了地下空间受洪水入侵灾害时含休息平台的阶梯水流的水力特性,得到了阶梯水流流场、初始掺气点、掺气浓度分布、水气混合速度及阶梯平台挑流等特性,并验证了不含清水层的两个水气交界面掺气水流掺气浓度分布的基本形式。 再次,根据试验结果和数值模型的相关理论,构建并验证了阶梯水流流场数值模拟模型,并基于数值模型的灵活性和可变性,模拟了休息平台、阶梯坡度和阶梯形态对水流流场的影响,分析了有无休息平台、不同阶梯坡度和不同阶梯形态下阶梯水流流态、流速分布及其对被困人员的安全撤离的影响。 最后,提出了复杂水流工况下突出自由液面的柱体绕流作用力的测量方法,制作出测量装置,并通过三种方式验证了该装置测力时的精度；简化人体绕流为柱体绕流,并考虑单人或多人同时撤离的不同情况,试验研究了单柱体在不同入侵水深和在阶梯不同位置工况下、多柱体在不同的排列状况下的绕流流场与水流作用力,并据此计算分析绕流阻力系数。 论文的创新点在于：针对阶梯水流的高掺气率、且在休息平台后的挑流含有两个水气交界面的特点,推导出含两个气相线(面)源(两个水气交界面)的掺气水流浓度分布的基本形式,并结合试验数据进行了验证；结合物理试验与数值模拟,研究了休息平台、阶梯坡度与阶梯形态(直线型、90°转弯L型与1800转弯U型)对阶梯水流水力特性的影响；针对复杂水流工况下突出自由液面的竖直及斜置柱体在恒定及非恒定水流工况下作用力的测量问题,提出并制作出相应的测量装置,且应用于阶梯上柱体绕流作用力的测量；试验研究了阶梯上的单柱与多柱绕流特性,总结分析了阶梯上柱体的绕流阻力系数。
[Abstract]:With the large-scale construction and development of underground space and the frequent occurrence of extreme precipitation events in cities, the risk of water invasion in underground space is very high, and the disaster event of water invasion in underground space can not be ignored. The entrance and exit ladder of underground space is the key channel for the evacuation of trapped people when flooding the river or heavy rain and water intrusion, and has become a very high risk area to threaten the safe evacuation of pedestrians. In order to explore the safety of evacuation of trapped people in underground space water invasion disaster, this paper studies the hydraulic characteristics of water flow on the ladder used for pedestrian walking during water invasion disaster and the flow characteristics of human body (simplified as cylinder). The main contents are as follows: firstly, the types of step aerated flow and the causes of aerated flow are summarized. The aerated flow is divided into aerated flow in clear water layer and aerated flow without clear water layer, and the movement law of aerated flow is analyzed. The aeration movement mechanism of aerated flow at different water-gas interface is summarized, and according to the related theory of flow aeration, The basic form of aeration concentration distribution of two gas line (surface) sources (two water-gas interface) and the calculation method of hydraulic characteristic parameters are derived. Secondly, according to the selected underground space entrance and exit shape and hydraulic model test principle, the underground space entrance and exit ladder comprehensive test platform with intermediate rest platform is designed and manufactured. The hydraulic characteristics of stepped flow with rest platform in underground space subjected to flood invasion are studied experimentally. the characteristics of stepped flow field, initial aeration point, aeration concentration distribution, water and gas mixing velocity and ladder platform flow are obtained. The basic form of aeration concentration distribution of two water-gas interface aerated flow without clear water layer is verified. Thirdly, according to the experimental results and the related theories of the numerical model, the numerical simulation model of stepped flow field is constructed and verified, and the rest platform is simulated based on the flexibility and variability of the numerical model. The influence of ladder slope and ladder shape on the flow field is analyzed, and the flow pattern, velocity distribution and its influence on the safe evacuation of trapped people with or without rest platform, different ladder slope and different ladder form are analyzed. Finally, the measurement method of the flow force around the cylinder protruding the free liquid level under complex flow conditions is put forward, and the measuring device is made, and the accuracy of the device is verified by three ways. The flow around the human body is simplified as the flow around the cylinder, and considering the different situations of single or multiple people evacuating at the same time, the single cylinder is tested and studied under different invasive water depths and different positions of the ladder. The flow field and flow force around the multi-cylinder under different arrangement conditions, and the resistance coefficient around the flow is calculated and analyzed. The innovation of this paper is that in view of the high aeration rate of stepped flow, and the flow carrying after the rest platform contains the characteristics of two water-gas interface. The basic form of aerated flow concentration distribution with two gas line (surface) sources (two water-gas interface) is derived and verified by the experimental data. Combined with physical test and numerical simulation, the effects of rest platform, ladder slope and ladder shape (linear, 90 掳turning L-shaped and 1800 U-shaped) on the hydraulic characteristics of stepped flow are studied. In order to solve the problem of measuring the vertical and oblique cylinder force of protruding free liquid level under constant and unstable flow conditions under complex flow conditions, the corresponding measuring device is put forward and made, and applied to the measurement of flow force around the cylinder on the ladder. The flow characteristics of single column and multi-column on the ladder are studied, and the flow resistance coefficient around the cylinder on the ladder is summarized and analyzed.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV131.3
本文编号：2494143
[Abstract]:With the large-scale construction and development of underground space and the frequent occurrence of extreme precipitation events in cities, the risk of water invasion in underground space is very high, and the disaster event of water invasion in underground space can not be ignored. The entrance and exit ladder of underground space is the key channel for the evacuation of trapped people when flooding the river or heavy rain and water intrusion, and has become a very high risk area to threaten the safe evacuation of pedestrians. In order to explore the safety of evacuation of trapped people in underground space water invasion disaster, this paper studies the hydraulic characteristics of water flow on the ladder used for pedestrian walking during water invasion disaster and the flow characteristics of human body (simplified as cylinder). The main contents are as follows: firstly, the types of step aerated flow and the causes of aerated flow are summarized. The aerated flow is divided into aerated flow in clear water layer and aerated flow without clear water layer, and the movement law of aerated flow is analyzed. The aeration movement mechanism of aerated flow at different water-gas interface is summarized, and according to the related theory of flow aeration, The basic form of aeration concentration distribution of two gas line (surface) sources (two water-gas interface) and the calculation method of hydraulic characteristic parameters are derived. Secondly, according to the selected underground space entrance and exit shape and hydraulic model test principle, the underground space entrance and exit ladder comprehensive test platform with intermediate rest platform is designed and manufactured. The hydraulic characteristics of stepped flow with rest platform in underground space subjected to flood invasion are studied experimentally. the characteristics of stepped flow field, initial aeration point, aeration concentration distribution, water and gas mixing velocity and ladder platform flow are obtained. The basic form of aeration concentration distribution of two water-gas interface aerated flow without clear water layer is verified. Thirdly, according to the experimental results and the related theories of the numerical model, the numerical simulation model of stepped flow field is constructed and verified, and the rest platform is simulated based on the flexibility and variability of the numerical model. The influence of ladder slope and ladder shape on the flow field is analyzed, and the flow pattern, velocity distribution and its influence on the safe evacuation of trapped people with or without rest platform, different ladder slope and different ladder form are analyzed. Finally, the measurement method of the flow force around the cylinder protruding the free liquid level under complex flow conditions is put forward, and the measuring device is made, and the accuracy of the device is verified by three ways. The flow around the human body is simplified as the flow around the cylinder, and considering the different situations of single or multiple people evacuating at the same time, the single cylinder is tested and studied under different invasive water depths and different positions of the ladder. The flow field and flow force around the multi-cylinder under different arrangement conditions, and the resistance coefficient around the flow is calculated and analyzed. The innovation of this paper is that in view of the high aeration rate of stepped flow, and the flow carrying after the rest platform contains the characteristics of two water-gas interface. The basic form of aerated flow concentration distribution with two gas line (surface) sources (two water-gas interface) is derived and verified by the experimental data. Combined with physical test and numerical simulation, the effects of rest platform, ladder slope and ladder shape (linear, 90 掳turning L-shaped and 1800 U-shaped) on the hydraulic characteristics of stepped flow are studied. In order to solve the problem of measuring the vertical and oblique cylinder force of protruding free liquid level under constant and unstable flow conditions under complex flow conditions, the corresponding measuring device is put forward and made, and applied to the measurement of flow force around the cylinder on the ladder. The flow characteristics of single column and multi-column on the ladder are studied, and the flow resistance coefficient around the cylinder on the ladder is summarized and analyzed.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV131.3
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