What is a weir contraction?

What is a weir contraction?

A contracted weir means that the ditch or canal leading up to the weir is wider than the weir opening itself. The water before the weir should be held in a relatively calm and smooth pool.

What is Francis formula?

The Francis (1883) equation is convenient for weirs operating under favorable prescribed conditions. The Francis equation is: Q = 3.33h13/2(L-0.2h1) (7-4)

What is the difference between weir and notch?

Basically there is no difference between a notch and a weir, except that a notch is of small size while a weir is of large size. A notch is usually made of metal plate whereas a weir is made of masonry or concrete. The bottom edge over which the water flows is called the sill or the crest of water the notch.

What is sharp crested weir?

Sharp crested weirs (also called thin-plate weirs or notches) are used to obtain discharge in open channels by solely measuring the water head upstream of the weir. Weirs are extensively used in irrigation practices, laboratories and industry.

What is depressed nappe?

A depressed nappe is partially ventilated, which creates negative pressure beneath the nappe. The negative pressure leads to a 6% to 7% increase in discharged water compared to a free nappe. Clinging nappes have no air beneath, and the stream flows along the face of the weir.

What is crest of a triangular notch?

For V-notch weirs, the point of the triangle is the crest. The lowest elevation of the notch over which water flows is the zero reference elevation against which head is measured.

What is triangular weir?

Triangular weirs are sharp crested thin plates with V-shaped opening (or notch). These plates are installed at the exit of a channel, tank, or basin in order to measure the real-time flow of water. For a given weir profile size and shape, the flow of water is related to the head of water at the weir.

What is weir flow?

A flow measuring weir is simply a structure over which water flows in such a way that volumetric flow rate can be calculated…. it lets you know how much water is flowing. Many times a flow measuring weir is simply a thin plate across a flow stream, but weirs can also be broad, thick structures.

What is end contraction in notches?

An end contraction is when the length of the weir (L) is less than the width of the Channel and a nappe contracts either one or both sides of the weir.

What is V notch?

Triangular weirs are sharp crested thin plates with V-shaped opening (or notch). These plates are installed at the exit of a channel, tank, or basin in order to measure the real-time flow of water. A typical application for these plates consists in measuring the flow of water on the downstream side of a dam.

What is rectangular weir?

A sharp crested, rectangular weir is simply a flat plate obstruction in an open channel flow path, with a straight, level opening to allow water flow over the weir, as shown in the pictures and diagrams in the rest of this article.

What is Crest in weir?

A weir is an overflow structure placed across the flow. The edge over which the flow occurs is called the crest of the weir. Stage is generally measured relative to the weir crest. The crest of a weir may be sharp (metal plates) or broad (small dams or humps).

What does the D in the end of a contraction mean?

Most contractions ending in ‘d and ‘s are ambiguous. The ‘d can represent either had or would ; ‘s can represent either has or is. All the same, the meaning of these contractions is usually clear from their context.

What do you mean by end contraction in weirs?

Based on how the expression is used there, I gather that it really refers to the reduction in width of the sheet of water flowing over the weir. That is, the ends contract inward (because there is a flow inwards along the walls across the flow leading in to the weir).

What does it mean when contractions don’t get longer?

Contractions that are not getting longer, stronger and closer together. This may mean that the contractions are not opening the cervix. It usually means that other work is being done, such as turning your baby to a different position, softening or thinning the cervix.

When do you use contractions in English grammar?

What Are Contractions in English Grammar? In English, contractions are used to combine words in casual speech or writing by dropping one or more letters. In English, contractions are used to combine words in casual speech or writing by dropping one or more letters. Menu. Home.