如何测量水电项目中的水头和流量

测量头and Flow

头部和流量是您需要了解您网站的两个最重要的事实。没有这些测量，你根本就无法前进。您的头部和流量将确定有关水电系统管道尺寸，涡轮机类型，转速，发电机尺寸的一切 - 一切。甚至艰难的成本估计是不可能的，直到你测量的头部和流量。还要记住，准确性很重要。除非您的测量准确，否则您最终可能最终设计为错误的规格，以更高的价格生产更少的功率，而不是否则可能的瓦特。

测量头

头的压力,由避署的差异vation between the intake of your pipeline, and your water turbine. Head can be measured as vertical distance (feet or meters) or as pressure (pounds per square inch, newtons per square meter, etc.). Regardless of the size of your stream, higher HEAD will produce greater pressure – and therefore power – at the turbine.

The following conversions may be helpful:

1垂直脚=每平方英寸0.433磅（PSI）压力

1 psi = 2.31 vertical feet

Accuracy is critical when measuring HEAD. It not only affects power, but also determines the type of turbine to use (such as a Francis or Pelton design), as well as the hydrodynamic design of the turbine buckets or blades. An altimeter can be useful in estimating Head for preliminary site evaluation, but should not be used for the final measurement. It is quite common for low-cost barometric altimeters to reflect errors of 150 feet or more, even when calibrated. GPS altimeters are often even less accurate.

测量头部有两种准确的方法：直接距离测量和水压。

直接测量

You can use a surveyor’s transit, a contractor's level on a tripod, or a level taped to a straight board to measure头。您还需要一个具有刻度测量的杆。（粘贴到PVC管的20'部分的测量胶带运行良好。）直接测量需要助理。使用运输水平和垂直测量杆制作一系列垂直测量。确保每个运输设置正好级别，确保测量杆是垂直的。在每个步骤中保持详细说明，然后加上一系列测量（A，B，C，D等）以找到总头。

水压测量如果距离足够短，则可以使用一个或多个花园软管来测量头部。该方法依赖于头部每个垂直脚的恒定产生0.433 psi的水压。（10个垂直脚会产生4.33 psi。）通过测量软管中的压力，您可以计算系统的高程变化。从您所提出的进气场运行软管（或软管）到所提出的涡轮机位置。如果将多个软管连接在一起，请确保每个连接都紧密且无泄漏。将精确的压力表连接到软管的底端，并用水完全填充软管。确保软管中没有高点，可以捕获空气。如有必要，可以通过移动软管并采取多个读数来测量总头在更长的距离上。然而，请记住，每个垂直脚都有少于半psi差异。除了非常陡峭的山坡外，甚至一百只脚软管也可能只掉下几英尺。 The chance for error significantly increases with a series of low-Head readings. Use the longest possible hose, along with a highly accurate pressure meter, to measure HEAD.The pressure meter must be graduated so that measurements are taken in the middle of the pressure gauge's range. Don't use a 0 - 800 PSI gauge to measure 5 -15 PSI pressure. Select instead a 0 - 30 PSI gauge.

GrossHead vs.净Head

通过记录这些实际测量，您已经确定了总头。然而，如稍后在计算网头中所述，由于管道（Penstock）摩擦，喷嘴处的有效头实际上实际降低。适当设计的管道将产生净头的净头约为您衡量的总头部。

Measuring Flow

流级别通过季节改变，因此在一年中的各个时间来衡量流量非常重要。如果是不可能的，则尝试通过与邻居讨论流来确定各种年度流量，或者为您的流或附近的较大的流找到政府地质调查流量数据。还要记住，鱼，鸟类，植物和其他生活依赖于您的生存流。

Especially during low water seasons, avoid using all the water for your hydro system.

流动通常表示为每秒或分钟的一定体积的水。常见的例子是每秒加仑或升（或分钟），立方英尺或立方米（或分钟）：每个可以很容易地转换为另一个，如下：

1立方英尺= 7.481加仑

1 cubic meter = 35.31 cubic feet

1 cubic meter = 1,000 liters

There are three popular methods for measuring FLOW: using a Container, Float, or Weir. Each will be described in detail below. Once again, accuracy is important to ensure correct system design and optimum power generation.

Method 1: Measuring Time to Fill Container The Container Fill method works only for very small systems. Build a temporary dam that forces all the water to flow through a single outlet pipe, Using a bucket or larger container of a known volume0.625 gps / 7.481 = 0.0835 cubic feet per second (cfs).

Method 2: Measuring with a Float

The Float method is useful for large streams if you can locate a section about 10 feet long where the stream is fairly consistent in width and depth.

STEP 1: Measure the average depth of the stream. Select a board able to span the width of the stream and mark it at one-foot intervals. Lay the board across the stream, and measure the stream depth at each one-foot interval. To compute the average depth, add all of your measurements together and divide by the number of measurements you made.

STEP 2: Compute the area of the cross section you just measured. Multiply the average depth you just computed by the width of the stream. For example, a 6-foot wide stream with an average depth of 1.5 feet would yield a cross section area of 9 square feet.

STEP 3: Measure the Speed. A good way to measure speed is to mark off about a 10-foot length of the stream that includes the point where you measured the cross section. Remember, you only want to know the speed of the water where measured the cross section, so the shorter the length of stream you measure, the better. Using a weighted float that can be clearly seen (an orange works well), place it in the stream well upstream of your measurement area, and then use a stopwatch to time how long it takes to cover thelength of your measurement section (e.g. 10 feet). The stream speed probably varies across its width, so record the times for various locations and average them. With these time and distance measurements, you can now compute the water speed.

例如，让我们假设浮动需要5秒钟，以便旅行10英尺：

10英尺/ 5秒=每秒2英尺，或

2 feet per second x 60 = 120 feet per minute

然后，您可以通过乘以横截面区域行进的脚来计算流量。使用我们的横截面区域和速度示例：

每分钟120英尺x 9平方英尺=每分钟1,080立方英尺（CFM）流动

STEP 4: Correct for Friction. Because the stream bed creates friction against the moving water, the bottom of the stream tends to move a little slower than the top.This means actual flow is a little less than what we computed. By multiplying our result by 0.83, we get a closer approximation of actual flow:

1,080 CFM X 0.83 = 896.4 CFM（立方英尺/分钟），或896.4 CFM / 60 = 14.94 CFS（立方英尺/秒）

Method 3: Measuring with a Weir.

A Weir is perhaps the most accurate way to measure small and medium sized streams. All the water is directed through an area that is exactly rectangular, making it very easy to measure the height and width of the water to compute FLOW. A Weir is a temporary dam with a rectangular slot, or Gate. The bottom of the Gate should be exactly level, and the width of the Gate should allow all the water to pass through without spilling over the top of the dam. A narrower Gate will increase the depth of the water as it passes through, making it easier to measure.

值得注意的是，由于水深在移动通过栅极时，您的深度测量不会截取。相反，在堰门的上游插入股份，并使桩的底部与智力门的底部完全水平。从桩的顶部释放水的深度。