How
to tell if a stream will develop the horsepower to generate
electricity.How
to tell if a stream will develop the horsepower to generate
electricity.
First find out how many gallons per minute of water will flow past a given point in the stream.
To do this put up a temporary board dam with a notch or weir cut into the top board.
...
To figure out the amount of water flowing through the weir, use this formula.
Three times the width of a weir, times the square root of t...
he depth of the water.
As a example, a weir notch 25 inches wide with 4 inches of water flow going over it will equal 400 gallons per minute (25 x 16 (4x 4) flow.
(Note my math is subject to analysis and correction by those better then mathematics then I)
Now to determine horsepower available multiply the gallons per minute water flow times the height of your dam (The number of feet the water will fall from the top of the dam breast to the water surface below )
In the case of a 400 gallon per minute flow and 10 foot head you will get about 1 horsepower of usable work from the water flow following the formula (rate of flow times height divided by 4000 equals the horsepower of work available from the water flow.).
Another method to determine the horsepower available from a given stream of water is called the float method.
Take a weighted piece of wood. Let it float down the stream in a strait stretch in the middle. Measure how far it floats in a minute. (you must weight the float by tying a weighted line to it so that the surface current and the wind will not push the float along faster then the water current is actually going.).
If the float moves 25 feet in a minute that will be your velocity.
Multiply your velocity by .75 to get your average stream flow. (25 x .75 = 18.75 feet per minute true stream velocity)
Now calculate the average width and depth of the stream. Multiply this by the velocity to give the cubic volume of water flow.
For example Average width of 6 ft by average depth of 3.5 ft with a velocity of 18.75 feet per minute flow to get a average flow of 393.75 feet per minute. Now say you have a drop of 9 feet. Multiply this equals 3543.75.
Horsepower available equals the weight in pounds of a cubic foot of water (62.5 pounds per cubic foot of water) times the flow of water in cubic feet per minute times the fall of the water, divided by the constant of 33,000 (3543.75 x 62.5 = divided by 33,000 = 6.7 horsepower.
Now multiply that by .8 because the the falling water is reckoned to be only 80% efficient in converting power. (6.7 x .8 = a practical actual horsepower rating of 5.36 for that streams head of water.
My grandpa taught me this and I never thought I would be able to use it, now, it may be the "High Tech" of a grid down future.
For those of you near moving water this is the math to make it useful to you.
More such articles at
https://www.facebook.com/Survivalist.and.Preppers.Haven
First find out how many gallons per minute of water will flow past a given point in the stream.
To do this put up a temporary board dam with a notch or weir cut into the top board.
...
To figure out the amount of water flowing through the weir, use this formula.
Three times the width of a weir, times the square root of t...
he depth of the water.
As a example, a weir notch 25 inches wide with 4 inches of water flow going over it will equal 400 gallons per minute (25 x 16 (4x 4) flow.
(Note my math is subject to analysis and correction by those better then mathematics then I)
Now to determine horsepower available multiply the gallons per minute water flow times the height of your dam (The number of feet the water will fall from the top of the dam breast to the water surface below )
In the case of a 400 gallon per minute flow and 10 foot head you will get about 1 horsepower of usable work from the water flow following the formula (rate of flow times height divided by 4000 equals the horsepower of work available from the water flow.).
Another method to determine the horsepower available from a given stream of water is called the float method.
Take a weighted piece of wood. Let it float down the stream in a strait stretch in the middle. Measure how far it floats in a minute. (you must weight the float by tying a weighted line to it so that the surface current and the wind will not push the float along faster then the water current is actually going.).
If the float moves 25 feet in a minute that will be your velocity.
Multiply your velocity by .75 to get your average stream flow. (25 x .75 = 18.75 feet per minute true stream velocity)
Now calculate the average width and depth of the stream. Multiply this by the velocity to give the cubic volume of water flow.
For example Average width of 6 ft by average depth of 3.5 ft with a velocity of 18.75 feet per minute flow to get a average flow of 393.75 feet per minute. Now say you have a drop of 9 feet. Multiply this equals 3543.75.
Horsepower available equals the weight in pounds of a cubic foot of water (62.5 pounds per cubic foot of water) times the flow of water in cubic feet per minute times the fall of the water, divided by the constant of 33,000 (3543.75 x 62.5 = divided by 33,000 = 6.7 horsepower.
Now multiply that by .8 because the the falling water is reckoned to be only 80% efficient in converting power. (6.7 x .8 = a practical actual horsepower rating of 5.36 for that streams head of water.
My grandpa taught me this and I never thought I would be able to use it, now, it may be the "High Tech" of a grid down future.
For those of you near moving water this is the math to make it useful to you.
More such articles at
https://www.facebook.com/Survivalist.and.Preppers.Haven
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