SU448350A1 - Gauge for parabolic trays - Google Patents

Description

one

The invention relates to the field of irrigated farming for water accounting in canals from parabolic reinforced concrete trays.

The known water metering device is characterized by the deposition of bottom and suspended pumps in front of it, which violates the flow characteristic established by calibration.

In the proposed water metering device, the aperture threshold is located at the bottom of the tray channel, the diaphragm cutout is made in the form of a parabola, the parameter of which is chosen from the condition of uniform lateral compression of the flow but the entire depth necessary to form a deflected wave jump.

Due to this, it is possible to skip bottom pumps and obtain a stable flow characteristic.

The drawing shows a diagram of the device.

With a pre-critical flow rate in the channel and outflow through the diaphragm 1 with a pointed edge in the pools of the water meter, a nonrepair of levels is established, which is determined by the difference in readings of the water rails 2 and 3. The flow of water depends on the area of the living cross section of the flow in upstream and downstream and the flow coefficient determined by the calibration of the device. Dependence for determining the flow of water, the passage w, through the diaphragm, has

following view:

Q 1.33 / HA3 / 2 | / 2gA / yp,

Q - water consumption in the trough channel;

where P is the parameter of a parabola, characterizing the shape of the cut-out of the diaphragm; consumption coefficient determined by calibration;

0

H aya

depth of flow above the weir threshold in the upstream; the difference in water levels in the upper and lower pools;

g - free fall acceleration.

5 In channels with supercritical velocity, a discharged wave jump occurs in the lower pool when it flows through the diaphragm. The flow in this case is determined by the formula

0

Q l, 33mHy2gP.

Subject invention

Water gauge parabolic device

The 5 trays, containing the diaphragm and two gauges, are distinguished by the fact that, in order to ensure the flow of bottom sediments and to obtain a stable flow characteristic, the aperture threshold is located at the bottom of the trough channel, catching uniform lateral compression of the hyute and the aperture cut is the shape over the entire depth required for the image of the parabola, the parameter of which is chosen from the depth of the driven away wave jump.

448350

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