给排水工程屋顶排水中英文对照外文翻译文献

中英文对照外文翻译
(文档含英文原文和中文翻译)
Short and Long Term Advantage roof drainage design performance Decade has witnessed great changes in the design of the roof drainage system recently, particularly, siphon rainwater drainage system has been gradually improved, and there is likely to be the key application. At the same time these changes, urban drainage system design has undergone tremendous changes, because the scope of a wider urban drainage system design for sustainable development, as well as people for climate change flooding more attention. The main contents of this article is how to design roof drainage systems and make a good performance. Special attention is how to get rid of bad habits already formed the design, but also need to consider innovative roof drainage system, such as green roofs and rainwater harvesting systems.
Practical application: In the past few years, the design of the roof rainwater drainage system has undergone tremendous changes. On large buildings, siphon rainwater drainage technology has been very common, as well as green roofs because it is conducive to green development, being more and more applications. Taking into account the ongoing research, this article focuses on how to effectively design a variety of roof rainwater drainage system, and make it achieve the desired design effect.
1. Introduction
In the past decade, the city and the water drainage system design has been widely accepted thinking about sustainable urban drainage system, or the optimal management direction. The main principles of the design of these systems is both a local level in line with the quality of development, but also to create some economic benefits for the investors. This principle has led to the development of new changes in the sump. Although the application of such a device is
gradually reduced, but the urban environment relatively high demand areas still require 100% waterproof and rapid drainage, such as the roof. Typically roof drainage system in the design, construction and maintenance has not been given due attention. Although the drainage system investment costs account for only a small portion of the total construction investment, but not able to judge the loss caused by poor design.
There are two different forms of roof drainage system design methods, namely the traditional and siphon method. Traditional systems rely on atmospheric pressure work, the drive ram affected sink flow depth. Therefore, the conventional roof drainage systems require a relatively large diameter vertical drop tube, prior to discharge, all devices must be connected to the groundwater collection pipe network. In contrast, siphonic roof drainage pipe systems are generally designed to full flow (turbulent flow means that require less exhaust pipe), which will form a negative pressure, the larger the higher flow rate and pressure head. Typically siphon system requires less down pipe work under negative pressure to the water distribution network can mean higher altitude work, thereby reducing the amount of underground pipe network.
Both systems consists of three parts: the roof, rainwater collection pipes, pipe network.
All of these elements are able to change the water pressure distribution system. This section focuses on the role and performance of each part. Due to the principle of siphon system has not been well understood, resulting argument is relatively small, this article will highlight siphon system.
2. Roof
The roof is usually designed by the architect, designer and not by the drainage design. There are three main roof.
2.1 Flat roof
Flat roofs are used in industrial buildings less rainfall regions and countries. This roof is not completely flat, but lower than the minimum roof slope may require. For example, the United Kingdom require maximum slope of 10 °. Setting minimum slope in order to avoid any unnecessary water.
Despite the flat roof if it is not properly maintained will have more problems, but it will reduce the dead zone within the building, and the ratio of sloping roofs in favor of indoor air.
2.2 sloping roofs
Most residential and commercial buildings are pitched roof, inclined roof is the biggest advantage can quickly drain, thereby reducing leakage. In temperate regions, we need to consider carrying roof snow load. Once it rains, rainfall through the sloping roofs can be determined by calculation. When rainfall data can be used, you can use the kinematic theory to solve such problems.
2.3 green roof (flat or inclined)
It can prove roof is the oldest green roofs, including rainfall can reduce or disperse roof planted with plants. It can be planted with trees and shrubs roof garden, it can also be a vegetated roof light carpet. Wherein the latter technique has been widely used. Some of these applications tend to focus on aesthetic requirements and are often used in green development. Since the aesthetic requirements and pressure requirements, as well as green roofs thermal insulation function, reduce the heat island effect, silencer effect, extend the life of the roof.
Green roofs in Germany, the most widely used, followed in North America, but to consider the impact on the aesthetics. Germany is by far the most experienced countries in the 19th century
have practical application, then as an alternative to reduce the risk of fire tar roof an option in urban areas. Germany is currently the main research question on the cultivation of other issues to consider smaller cities. A study from 1987 to 1989, was found packed with 70 mm thick green roof can be reduced by 60% -80% of heat loss. In a Canadian work computer model based on the roof indicates that as long as the sump, the area can reach 70% of the roof area can be reduced by 60 percent in one year, the same model was also used for artificial rainfall, which the results indicate that rainfall in the catchment season helps to drain away rainwater.
However, none of these studies show that green roofs can play a useful role in the rainfall season, or how high collection efficiency of water supply. The United States did some tests, as long as the green roofs regular watering, can reduce 65 percent of the runoff in a rainfall. America's most authoritative green roof guidelines by the New Jersey state environmental agencies promulgated. The main principle is to solve the structural problems of light, and how can the normal drainage after two years.
Rainfall period is based on the probability of failure is determined. The system is typically based on rainfall during rainstorms two minutes, two minutes, have a choice. Although this model will get more traffic, but there is no other better alternative. Studies have shown that the traditional model is applied to study green roofs are premature.
Loss factor than traditional roof records should be small, about 98.7%.
Peak flow will be reduced, although not penetrate, the surface roughness but also have a significant impact.
Concentrated rainfall than two minutes for a long time, especially for large roof areas, such as public buildings, commercial buildings, industrial buildings.
Urban drainage design should also consider other factors, for a complex system, a green roof in a rain is not enough. Water flow duration curve shows a longer than traditional systems. And two independent and will affect between is possible, which requires a more precise time period. 3. Rainwater Collector
Basic requirements rainwater collector is designed to be able to accommodate rainfall rainstorms. Although it is possible to make a slightly inclined roof drainage purposes, but the nature of the construction industry and building settlement will become flat roof Typically, the tank is placed in a horizontal, sectional view of the water is outwardly inclined, which the role of hydrostatic.
3.1 drain outlet
Analyzing rainwater collector has sufficient volume is the key to the sump outlet external setting conditions. Also affect the flow rate into the storm water drainage system piping, but also affect the depth of the water catchment. Although the depth of the sump will not bring any particular problems, but too deep can cause excessive sump.
Numerous studies in the 1980s showed that the flow of conventional roof drainage system outlet can be divided into two cases. It depends on the size of the depth and size of the outlet. When the water depth is less than half the diameter of the outlet, the flow of the first type, and the outlet of the flow can be calculated by an appropriate equation; water depth increases, exports are slowly clogging the flow will become another form forms, at the same time, the flow of exports can be obtained through other equations. While conventional roof drainage systems are designed to be free-draining, but may cause limitations encountered in the design of the flow is not free. In this case, it will require additional depth.
Siphon roof drainage systems, the outlet is designed to be submerged stream. In this case, the depth of the outlet of the decision is more complicated, because the design of the sump depends on the flow. Recent studies have shown that conventional roof drainage systems use a variety of non-standard catchment, their depth and height, bigger than the diameter of the outlet. This will eventually result in a siphon effect. For a given catchment, the flow depends on the starting end of the drop tube diameter. A similar phenomenon has also been used to study the standard catchment, in these circumstances, only limited siphon action occurs within relatively close distance from the exit.
3.2 tank flow classification
In the complex flow sump outlet flow classification, can be seen from Table 2a, the flow will be uniform layering, regardless of whether the same inlet flow. Table 2b and 2c show, export distribution will greatly influence the flow.
When the outlet is not a free jet, sump outlet complex flow classification is difficult to describe. Because each catchment tank pressures are likely to be merged. For example, the siphon tube system design point is at near full jet outlet flow classification depends on the energy loss of each branch.
3.3 hydrostatic sectional
Sump shape of the water surface in the canal can be classified according to the flow equation. In most cases, a low flow rate means that there is less friction loss, if exports are free jet, the friction loss is negligible cross-section through the hydrostatic equation 1 to determine the horizontal distance.
Where Q-- flow (m3 / s)
T- surface width (m)
g- acceleration of gravity (m / s2)
F- flow area (m2)
Equation 1 can not be ignored when the friction required to correct (or very long pipe velocity is large), or not a free jet.
3.4 The current design methods
The previous discussion has highlighted the main factors that should be considered with sink design. However, without the help of a certain number of models, computing hydrostatic sectional roof drainage system, the volume of the sump is possible. This large commercial and manufacturing industry, is a development opportunity, you can merge several kilometers of water routes. Thus, the conventional drainage system sump design methods are mainly based on experience, and assume that exports are free jet.
Sump location in the building, it may cause the example to fail.
Different interface sump
Except in the case cited above, but also allows designers to use empirical data.
3.5 Digital Model
Large number of digital models can be used to accurately describe the flow of any form of catchment tank, regardless of whether the roof flows stable. An example of this model is a combination of roof space model. This model enables users to classify different aspects of the data indicated, includes: details of the rains, the roof surface drainage and other details. Kinematics have also been used to study rainwater tank to flow from the research collection. A typical method is based on open system to solve a basic problem of spatial mobility. This model automatically
resolve the sump outlet flow situation, but also to deal with the case of free jet can also be simulated space limited mobility and submerged discharge. Output values include depth and flow rate.
Currently, the model is essentially just a variety of research tools, but also through practical engineering test. However, we should face up to the various role models.
4 pipe systems group
Composition in the form and scope of the tube group determines the roof drainage system relies mainly on the traditional system or siphon action.
4.1 Traditional stormwater systems
Conventional roof drainage systems, the ground plane is generally vertical pipe-line network, connected to the sump outlet and underground drainage systems, critical systems as well as compensating tube. It should be emphasized that the angle between the ground and the compensating tube is less than 10 °. Capacity of the entire system relies mainly on the outlet tube instead of down.
Flow vertical tube is usually free-flowing, full of only 33%, the efficiency depends on the excess length of the tube. If the drop tube long enough (typically greater than 5m), there may be an annular flow. Similarly, under normal circumstances flow compensation pipe is free-flowing, full of up to 70%. Such designed process both for the design, various equations can also be used.
4.2 Siphon roof drainage system
In contrast with the traditional drainage systems, Siphon roof drainage system relies on air flow outside the system, and the tube is full pipe flow stream.
The designs are usually made on the assumption that the design of heavy rain, the system can quickly siphon discharge rainwater. This assumption allows the application of hydrostatic siphon system theory. Often used steady flow energy equation. While this approach ignores the small amount of energy loss at the entrance, but after the experiment showed that there are still conducive to practical use.
However, steady-state design methods in the siphon system is exposed to rain when the system does not meet the standard requirements or changes in rainfall intensity is large is not applied. In the first case, there will be some mixing of air quality, annular flow occurs. These problems are not integrated in the system when more serious. Because usually designed rains are common, it is clear now design methodology over time may not apply to siphon system. This is a major disadvantage, because the design of the main problem is the noise and vibration problems.
Despite the disadvantages of the prior design approach, but a lot of the world's very few engineering failure reports. When a failure occurs, most likely for the following reasons: An incorrect understanding of the operation points
Substandard materials list
Installation defects
Maintenance mismanagement
To overcome these disadvantages, we have recently launched a series of research projects, to discuss the siphon system, and the development of digital models. From this work we learn a lot. In contrast with conventional design methods of some assumptions, siphon system mainly has the following aspects:
1) non-flow system of full flow
2) levels of certain pipe-flowing full pipe flow
3) full pipe flow downstream propagation through a vertical pipe, riser, etc.
4) the inner tube flow occurs over the vertical section, the system to reduce the pressure
5) downward tube is full pipe flow, there will be air lock
6) appears completely siphon action until well into the air system is lower than a certain level
Table 4a column data indicate that below the design point, the system will siphon unstable flow, depth of the water collecting tank is insufficient to maintain the siphon action. Table 4b show that the unsteady flow in siphon system when it will appear.
Table 5 lists the data output of a digital model. It can be seen that the model can accurately describe the siphon action, siphon and steady state, the data also show that the model can accurately describe the complex siphon action.
5 Conclusion
This article has illustrated the critical roof drainage systems, but these are often overlooked in the urban drainage system design. This article also shows that the design process is a complex process, rely mainly on the performance of exports. The following conclusions are based on the design summed up:
1) Run depend on three interacting parts: the roof, sump, water pipes
2) Green roofs can reduce traffic and beautify the city
3) the export performance of the system is essential
4) siphon drainage system have a greater advantage in large-scale projects, but must be considered high maintenance costs
5) Design siphon drainage system should consider additional capacity and operational issues
Although the green roof is a more attractive option, but the traditional roof of a building in the country will continue to dominate. Green roofs will be gradually developed, and gradually been widely accepted. Similarly, the roof drainage system shown effective that it will continue to play a huge role in the commercial building drainage systems.
Roof drainage system of the greatest threats from climate change, existing systems tend to be not simply aging; rainfall patterns of change will result in inefficient operation, self-cleaning rate will be reduced. Changes in wind speed and the roof will also accelerate the aging of the roof, it is necessary to carry out maintenance. Taking into account the climate change, the increase in materials, roof collected rainwater will be more extensive. Currently, the amount of rain around the globe per person per day 7-300 liters in the UK, with an average consumption of 145L / h / d, of which only about one liter is used by people, about 30 per cent of the toilet, study shows If water shortage, rainwater collected on the roof of developed and developing countries are recommended approach.
屋顶排水设计性能的近期与远期优势
最近十年见证了屋顶排水系统设计方面的巨大变化，特别的是，虹吸雨水排水系统已经得到逐步改善，并且有可能得到重点应用。

发生这些变化的同时，城市排水系统设计已经发生了巨大的变化，因为适用范围更广的可持续发展城市排水系统设计，还有人们对于气候变化带来的洪水泛滥的更多关注。

这篇文章的主要内容就是，如何设计屋顶雨水排水系统并使之有良好的运行性能。

需要特别注意的是如何改掉已经形成的不良设计习惯，同时还要需要考虑屋顶排水系统的创新，如绿色屋顶和雨水收集系统。

实际应用：在过去几年，屋顶雨水排水系统的设计已经发生了巨大的变化。

在大型建筑物上，虹吸雨水排水技术已经很常见，还有绿色屋顶由于其有利于绿色发展，正得到越来越多的应用。

考虑到正在进行的研究，本文主要介绍如何有效地设计各种不同的屋顶雨水排水系统，并使其达到理想的设计效果。

1.绪论
在过去十年，城市与水排水系统设计已经想着广为接受的可持续发展城市排水系统或者最优管理方向发展。

设计这些系统主要原则是，既要有符合当地发展水平的质量，又要为投资者创造一定的经济效益。

这种原则已经引发了集水池发展方式新的变化。

尽管这种装置的应用正在逐渐减少，但是城市环境要求比较高的地区仍然要求100%防水且排水迅速，例如屋顶。

通常屋顶排水系统在设计、建造和维护时并没有受到应有的重视。

尽管排水系统的投资费用只占建筑总投资的一小部分，但是，并不能据此来判断设计不良带来的损失。

主要有两种不同形式的屋顶排水系统设计方法，分别是传统的和虹吸式方法。

传统的系统依靠大气压力工作，其驱动压头受到水槽流动深度的影响。

因此传统的屋顶排水系统需要一个直径相当大的垂直下降管，在排放之前，所有的装置都必须连接到地下水收集管网。

与此相反，虹吸式屋顶排水系统通常设计成满管流（紊流状态意味着只需要较小的排气管），从而会形成负压，较大的压头和较大的流速。

通常虹吸式系统需要较少的下降管，在负压状态下工作，意味着给
水管网可以较高的高度上工作，从而减少地下管网量。

两种系统都由三部分组成：屋顶，雨水收集管道，系统管网。

所有这些部分都能够改变系统的水压分布。

这部分主要关注各部分的作用和性能。

由于虹吸系统的工作原理并没有得到很好的理解，得到的论证比较少，本文将会重点介绍虹吸系统。

2.屋顶
通常屋顶是由建筑师设计的，而不是由排水设计者设计的。

主要有三种屋顶。

2.1平屋顶
平屋顶主要应用在降雨量比较少的地区和发达国家的工业建筑。

这种屋顶并不完全是平的，而是低于所规定的屋顶最小坡度。

例如，英国规定最大坡度为10°。

设定最小坡度是为了避免任何不必要的积水。

尽管平屋顶如果得不到正确的维护会产生较多的问题，但它会减少建筑物内的死区，且比斜屋顶有利于室内气流组织。

2.2斜屋顶
大多数居住建筑和商业建筑都是斜屋顶，斜屋顶最大的优点是可以迅速排水，从而可以减少漏水。

在温带地区，不需要考虑屋顶承载的降雪载重。

一旦下雨，斜屋顶通过的降雨量就可以通过计算确定。

当有降雨资料可以利用时，可以使用运动学理论来解决这类问题。

2.3绿色屋顶（平的或者是斜的）
可以证明最老的屋顶就是绿色屋顶，它包括可以减少或驱散降雨的种有植物的屋顶。

它可以是种有树和灌木的屋顶花园，也可以是长有植被的轻型屋顶地毯。

其中后一种技术已经得到广泛应用。

其中一些应用趋向于侧重美学要求并经常应用于绿色发展。

由于审美要求和水压要求，绿色屋顶还有热绝缘的功能，减少热岛效应，有消声作用，延长屋顶的使用寿命。

绿色屋顶在德国应用最为广泛，在北美地区次之，但是要考虑美学上的影响。

德国是目前为止最有经验的国家，早在19世纪就有实际应用，当时作为在城市地区替代焦油屋顶降低火灾危险的一种选择。

目前德国主要研究放在种植问题上，对城市的其它问题考虑较少。

从1987年到1989年的一项研究工作，发现装有70毫米厚的绿色屋顶可以减少60%-80%的热损失。

在加拿大的一项基于电脑
模型的工作，表明在屋顶只要集水器是、的面积能够达到屋顶面积的70%，在一年内就能减少60%，同样的模型也被用于人工降雨，其结果都表明集水器在降雨季有助于雨水排走。

但是这些研究都没有表明绿色屋顶在降雨季可以发挥多大的作用，或者给水管的收集效率有多高。

美国做了一些测验，只要对绿色屋顶经常的浇灌，就可以在一次降雨中减少65%的径流量。

美国最有权威的绿色屋顶指导原则是由新泽西州环保部门颁布的。

这项原则主要是解决轻型结构问题，以及如何在两年之后还能正常的排水。

降雨周期是根据是根据失败的概率决定的。

通常的系统是根据暴雨期间两分钟的降雨量，这两分钟是有选择的。

尽管这种模型会得到更高的流量，但是没有其他更好的替代方法。

研究表明，传统模型应用于绿色屋顶的研究是是不成熟的。

流失量系数比传统屋顶记录的要小，大约为98.7%.
峰值流量也会减少，虽然没有渗透，但是表面粗糙度也会产生显著的影响。

集中降雨的时间要比两分钟要长，特别是对面积较大的屋顶，如公共建筑、商业建筑、工业建筑。

城市排水设计还要考虑其他一些因素，对于一个复杂的系统来说，一个绿色屋顶在一场降雨中是不够的。

流量水位曲线显示的持续期要比传统系统长。

并且两场独立的将与之间的影响也是有可能的，这需要更加精确的时间周期。

3.雨水收集器
雨水收集器的基本要求是要能够容纳设计暴雨时的降雨量。

尽管通常情况下可以通过让屋顶稍微倾斜来达到排水的目的，但是建筑工业的性质及建筑物的沉降都会式屋顶变得平坦，在水平放置的水槽中，水的剖面是向外倾斜的，这是流体静力学的作用。

3.1排水沟出口的深度
判断雨水收集器是否具有足够容积的关键是集水器外部出口的设置情况。

还会影响流入雨水排水系统管道的流速，还会影响集水器的积水深度。

尽管集水器的深度不会带来什么特别的问题，但是过深会导致集水器过高。

20世纪80年代的大量研究表明，传统屋顶排水系统的出水口的流动情况可以分为两种情况。

这取决于水深与出口尺寸的大小。

当水深小于出口直径的一半
时，流动情况是第一种类型，并且出口的流动情况可以通过合适的方程计算出；随着水深的增加，出口会被慢慢堵塞，流动形式会变成另一种形式，同时，出口的流动情况可以通过其他方程得出。

尽管传统屋顶排水系统被设计成可以自由排水，但是设计中遇到限制可能会使出流不是自由的。

在这种情况下，就会需要额外的深度。

在虹吸式屋顶排水系统中，出水口被设计成淹没出流，。

在这种情况下，决定出水口的深度比较复杂的，因为集水器的设计取决于流动情况。

近期的研究表明，传统的屋顶雨水排水系统使用各种非标准的集水器，它们的深度和高度，都要比出口的直径大。

这最终会造成虹吸作用。

对于一个给定的集水器，始端的流动情况取决于下降管的直径。

类似的现象也被用于研究标准的集水器，在这些情况下，受限的虹吸作用只发生在离出口比较近的距离内。

3.2槽内的流动分类
在集水槽复杂流动出口的流动分类中，可以从表2a中看出，流动会出现均匀的分层，而不管入口的流动情况是否相同。

表2b和2c表明，出口的分布会极大的影响流动情况。

当出口不是自由射流时，集水槽中复杂出口的流动情况分类是很难描述的。

因为每个集水槽内的压力都有可能是合并的。

例如，虹吸系统中的管子在靠近设计点时是充满射流，出口的流动分类取决于每个支路的能量损失。

3.3静水剖面
集水器中水表面的形状可以根据渠内流动方程进行分类。

在大多数情况下，低流速意味着有较小的摩擦损失，如果出口是自由射流，那么摩擦损失是可以忽略的，静水剖面可以通过方程1来决定水平距离。

式中Q--流量(m3/s)
T—表面宽度（m）
g—重力加速度（m/s2）
F—流动面积（m2）
方程1在摩擦力不可忽略时需要进行修正（管道很长或流速很大时），或者不是自由射流。

3.4现行的设计方法
先前的讨论已经强调了设计与水槽时应该考虑的主要因素。

然而如果不借助于一定的数量模型，计算屋顶排水系统的静水剖面、集水槽容积是不可能的。

这对大型商业和制造业来说，是一个发展机会，可以合并几千米的水管路线。

因此，传统的排水系统的集水槽的设计方法主要是根据经验，并假定出口是自由射流。

集水槽在建筑物中的位置，可能会造成失败的例子。

不同的集水槽界面
除了上面列举的情况外，还允许设计者采用经验数据。

3.5数字模型
大量的数字模型可以用来准确描述任何形式的集水槽内的流动情况，不管屋顶流量是否稳定。

这种组合模型的一个例子是屋顶网模型。

这种模型使用户能够对不同方面的数据进行分类说明，包括：雨季降雨情况的详细情况，屋顶表面排水的详细情况等。

运动学也被用于研究雨水从流动到集水槽中的研究。

一种典型的方法是基于解决开式系统中一位空间流动基本问题。

这种模型自动解决集水槽出口流动情况，还能处理自由射流的情况，也能模拟空间中的受限流动以及淹没出流。

输出值包括深度、流速等。

目前，各种模型本质上还只是研究工具，还需要经过实际工程的检验。

然而，我们应该正视模型的各种作用。

4系统管组
管组的组成形式和范围决定了屋顶排水系统主要依靠的是传统系统还是虹吸作用。

4.1传统雨水系统
传统屋顶雨水系统中，地面管网上面通常是垂直管网，连接着集水槽的出口和地下排水系统，重要的系统中还有补偿管。

应该强调的是，补偿管与地面夹角小于10°。

整个系统的能力主要依靠的是出水口而不是下降管。

垂直管内的流动通常是自由流动，充满度只有33%，其效率取决于多余的管长。

如果下降管足够长（通常大于5m），就有可能出现环形流动。

同样的，补偿管内的流动通常情况下也是自由流动，充满度可达70%。

这样设计的管路既可以
用于设计，也可以用各种方程。

4.2虹吸式屋顶排水系统
与传统排水系统相反，虹吸式屋顶排水系统依靠系统外的空气流动，并且管内流动是满管流。

通常的设计都做了这样的假设，对于设计的暴雨，虹吸系统能够迅速排出雨水。

这种假设可以让虹吸系统应用水静压理论。

经常用到稳定流能量方程。

尽管这种方法忽略了进口处少量的能量损失，但经过实验表明还是有利于实际应用。

然而稳定状态的设计方法在虹吸系统暴露在雨水系统时的标准不符合要求或者降雨强度的变化很大时是不能应用的。

在第一种情况中，将会有一定质量的空气混入，出现环状流。

这些问题在系统不是一个整体时更为严重。

由于通常设计的降雨都是普通的，很明显现在的设计方法随着时间的推移可能会不适用于虹吸式系统。

这是一个主要的缺点，因为设计中的主要问题是噪声和振动问题。

尽管现有的设计方法有缺点，但世界上大量的工程却很少有失败的报告。

当出现失败时，很有可能是下面的原因：
对操作要点理解不正确
不合格的原材料明细表
安装缺陷
维护管理不当
为了克服这些缺点，最近已经开展了一系列研究工程，来讨论虹吸式系统，并发展数字模型。

从这项工作中我们学到很多。

与现有设计方法相反的一些假设，虹吸式系统主要有以下几个方面：
1) 系统中的流动是非充满流动
2) 水平流动的某些管段存在满管流
3)满管流向下游传播，通过垂直管，上升管等
4) 满管流出现在垂直段，系统内压力降低
5）下降管内是满管流，将会出现气塞
6）出现完全的虹吸作用，直到进入系统的空气低于一定的水平
表4a列的数据表明，在低于设计点时，虹吸式系统会出现不稳定的流动，集水槽内的深度不足以维持虹吸作用。

表4b表明非稳定流在虹吸式系统中何时
会出现。

表5列举了一个数字模型输出的数据。

可以看出，这种模型能够准确描述虹吸作用，以及稳定虹吸状态，数据也表明该模型能够准确描述复杂的虹吸作用。

5结论
本文已经图示说明了屋顶排水系统的关键，但这些在城市排水系统设计中往往被人们忽视。

本文也表明设计过程是一个复杂的过程，主要依靠出口的性能。

下面这些结论是根据设计总结出来的：
1）运行依靠三个相互作用的部分：屋顶、集水槽、水管
2）绿色屋顶可以减少流量，美化城市
3）出口对系统的性能至关重要
4）虹吸式排水系统在大型工程中有较大的优势，但是必须考虑高昂的维修费用
5）设计虹吸式排水系统应该考虑额外的容量和操作问题
尽管绿色屋顶是比较有吸引力的一种选择，但是传统屋顶在国内建筑物中将会持续占统治地位。

绿色屋顶将会逐步发展，并逐步被人们广泛接受。

同样的，屋顶排水系统所显示的高效表明它将会在商业建筑的排水系统中持续发挥巨大的作用。

屋顶排水系统的最大威胁来自气候变化，现有的系统并不是简单的趋向于老化；降雨形式的变化将会导致低效的运行，自我清洁的速率也会降低。

而且屋顶风速的变化也会加速屋顶的老化，因此十分有必要进行维修保养。

考虑到气候的变化，材料的增多，收集屋顶的雨水将会更为广泛。

目前，全球的雨水量大约为7到300升每人每天，在英国，平均消耗量为145L/h/d，这其中只有大约1升是人使用的，有大约30%用于厕所，研究表明，如果水资源短缺，收集屋顶雨水对发达国家和发展中国家都是值得推荐的方法。