CN112052425B - Automatic and accurate manual multi-sediment open channel flow metering method - Google Patents

Abstract

The invention discloses an automatic and accurate manual multi-sediment open channel flow metering method, which specifically comprises the following steps: s1, silting is judged; s2, obtaining the deposition thickness delta h; and S3, accurately metering the flow in a layered mode after the siltation is removed. The invention is suitable for a channel with much silt, fully considers the influence of siltation on flow calculation, and can measure the siltation thickness of the channel and automatically and accurately measure the flow after siltation is removed.

Description

Automatic and accurate manual multi-sediment open channel flow metering method

Technical Field

The invention relates to the field of hydraulic engineering, in particular to an automatic and accurate measuring method for the flow of a sediment-laden channel.

Background

The conventional liquid flow metering device comprises a radar flow meter and a laser/radar/ultrasonic liquid level meter, is mainly used for on-line automatic monitoring of channel flow, and is characterized in that a flow rate-liquid level measuring device is formed by utilizing an upper computer, a cable and monitoring equipment, and the instantaneous flow and the accumulated flow of an open channel are calculated and monitored by combining the channel section shape and time information and through a related theoretical formula. However, for a channel with much silt or a channel with a channel deposition section which changes too fast, the traditional flow velocity-liquid level measuring device cannot accurately measure the flow of the open channel, and two problems exist: 1. the silt deposit change condition of a multi-silt channel and the silt deposit thickness cannot be monitored. 2. The automatic and accurate measurement of the flow after the sediment deposition of the multi-sediment channel is removed can not be realized.

The channel bottom coefficient is related to the wet circumference and roughness of the channel, and the specific value is fitted by an algorithm and determined together with actual measurement.

The method for calculating the surface flow of the open channel is common knowledge in the technical field, and specifically, the surface flow is calculated by the water depth of the channel surface and the surface flow velocity together, and the surface flow velocity is calculated by a trend extrapolation method from v₁,v₂,..,v_nAnd (4) jointly determining.

The channel layering requirements are that each layer has the same fixed interval, and the layering number is related to the actual channel bottom width b, the layering interval delta H, the open channel slope length l, the actual water depth H, and the included angle alpha between the side slope and the channel bottom.

The calculation relationship is as follows:

and then judging the relation between the oxide layer and the bottom b of the channel, wherein the oxide layer is larger than b, the delamination is larger than 4 and smaller than b, the delamination is smaller than 4, the oxide layer is divided into 8 layers at most, and the oxide layer is divided into 2 layers at least.

Disclosure of Invention

The invention aims to provide an automatic and accurate flow metering method for a silt-laden channel, which can meter the silt deposition thickness in the channel and automatically and accurately meter the flow after deposition removal.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: the automatic and accurate flow metering method for the silt-laden channel specifically comprises the following steps:

s1, judging whether the siltation reaches a preset threshold value delta;

s2, obtaining the deposition thickness delta h;

and S3, accurately metering the flow in a layered mode after the siltation is removed.

Further, the specific method for determining fouling in step S1 is as follows: obtaining theoretical liquid level height h of channel water passing section₁Measuring the actual liquid level h of the channel water passing section by using a drop-in liquid level sensor₂The input liquid level sensor is kept on the upper surface of the deposit layer and moves at a constant speed perpendicular to the flow direction when h is₂And h₁Is less than or equal to a preset threshold value delta, the siltation is judged to occur, and when h is less than or equal to the preset threshold value delta₂And h₁If the ratio of (d) is greater than a preset threshold value delta, it is determined that silting does not occur.

Further, the calculation formula of the deposition thickness obtained in step S2 is Δ h ═ h₁-h₂ (1)

Wherein h is₁＝Lsinα (2)

Wherein L is the length of the side slope of the channel, and alpha is the included angle between the side slope and the bottom of the channel.

Further, the specific steps of accurately measuring the flow rate after the siltation removal in step S3 are as follows:

s3-1, dividing the water passing section into n layers, wherein the first layer is arranged at the lowest part;

s3-2, acquiring actual flow velocity v of different layering heights of water cross section_{1,2,3,..,n-1,n}；

S3-3, obtaining the height H between the upper bottom of each layer and the bottom of the channel according to the actual layering_{1,2,3,...,n-1,n}And calculating the width B of the upper bottom of each layer_{1,2,3,...,n-1,n}The calculation formula is

And calculating the width B of the upper bottom edge of the deposit_{Silting up}The calculation formula is

Wherein s is the slope ratio of the side slope of the original channel, and b is the width of the channel bottom of the original channel;

s3-4, obtaining the channel bottom coefficient K according to the actual situation of the channel section_B；

S3-5, calculating the layered flow Q of each layer_{1,2,3,...,n-1,n}The formula for n is 1

The calculation formula of n is more than or equal to 2

Flow Q corresponding to the same sedimentation layer_{Silting up}The corresponding calculation formula is

S3-6, the formula for accurately measuring the flow after removing the siltation is Q ═ Q₁+Q₂+...+Q_n-1+Q_n-Q_{Silting up}+Q_{Surface layer} (8)。

Furthermore, when the channel bottom width b is less than or equal to 25m, the number of layers is n less than or equal to 4.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: the invention is suitable for a channel with much silt, fully considers the influence of siltation on flow calculation, and can measure the siltation thickness of the channel and automatically and accurately measure the flow after siltation is removed.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a schematic diagram of the method of measuring fouling in a silt-laden channel of the present invention;

FIG. 2 is a functional diagram of the present invention;

FIG. 3 is a schematic view of the channel hierarchy of the present invention;

fig. 4 is a flow chart of the operation of the present invention.

Detailed Description

The invention comprises the following steps:

s1, judging whether the siltation reaches a preset threshold value delta;

s2, obtaining the deposition thickness delta h;

and S3, accurately metering the flow in a layered mode after the siltation is removed.

The specific method for determining silting in step S1 is as follows: obtaining theoretical liquid level height h of channel water passing section₁Measuring the actual liquid level h of the channel water passing section by using a drop-in liquid level sensor₂The input liquid level sensor is kept on the upper surface of the deposit layer and moves at a constant speed perpendicular to the flow direction when h is₂And h₁Is less than or equal to a preset threshold value delta, the siltation is judged to occur, and when h is less than or equal to the preset threshold value delta₂And h₁If the ratio of (d) is greater than a preset threshold value delta, it is determined that silting does not occur.

The calculation formula of the deposition thickness obtained in step S2 is Δ h ═ h₁-h₂ (1)

Wherein h is₁＝Lsinα (2)

Wherein L is the length of the side slope of the channel, and alpha is the included angle between the side slope and the bottom of the channel.

The specific steps of accurately measuring the flow rate after the siltation removal in step S3 are as follows:

s3-1, dividing the water passing section into 4 layers, wherein the first layer is arranged at the lowest part;

s3-2, acquiring actual flow velocity v of different layering heights of water cross section₁，v₂，v₃And v₄；

S3-3, obtaining the height H between the upper bottom of each layer and the bottom of the channel according to the actual layering_{1,2,3,...,n-1,n}And calculating the width B of the upper bottom of each layer_{1,2,3,...,n-1,n}The calculation formula is

And calculating the width B of the upper bottom edge of the deposit_{Silting up}Calculating the formulaIs composed of

Wherein s is the slope ratio of the side slope of the original channel, and b is the width of the channel bottom of the original channel;

s3-4, obtaining the channel bottom coefficient K according to the actual situation of the channel section_B；

S3-5, calculating the layered flow Q of each layer_{1,2,3,...,n-1,n}The calculation formula is

Layer 1 stratified flow:

layer 2 stratified flow:

layer 3 stratified flow:

layer 4 stratified flow:

flow Q corresponding to the same sedimentation layer_{Silting up}The corresponding calculation formula is

S3-6, the formula for accurately measuring the flow after removing the siltation is Q ═ Q₁+Q₂+Q₃+Q₄-Q_{Silting up}+Q_{Surface layer} (8)。

The above description is only presented as an enabling solution for the present invention and should not be taken as a sole limitation on the solution itself.

Claims (2)

1. The automatic and accurate manual multi-sediment open channel flow metering method is characterized by comprising the following steps of: the method specifically comprises the following steps:

s1, judging whether the siltation reaches a preset threshold value delta;

s2, obtaining the deposition thickness delta h;

s3, accurately measuring the flow rate in a layering mode after the siltation is removed;

the specific method for determining silting in step S1 is as follows: obtaining theoretical liquid level height h of channel water passing section₁Measuring the actual liquid level h of the channel water passing section by using a drop-in liquid level sensor₂The input liquid level sensor is kept on the upper surface of the deposit layer and moves at a constant speed perpendicular to the flow direction when h is₂And h₁Is less than or equal to a preset threshold value delta, the siltation is judged to occur, and when h is less than or equal to the preset threshold value delta₂And h₁When the ratio of (d) is greater than a preset threshold value delta, determining that siltation does not occur;

the calculation formula of the deposition thickness obtained in step S2 is Δ h ═ h₁-h₂ (1)

Wherein h is₁＝Lsinα (2)

Wherein L is the length of the side slope of the channel, and alpha is the included angle between the side slope and the bottom of the channel;

the specific steps of accurately measuring the flow rate after the siltation removal in step S3 are as follows:

s3-1, dividing the water passing section into n layers, wherein the first layer is arranged at the lowest part;

s3-2, acquiring actual flow velocity v of different layering heights of water cross section_{1,2,3,..,n-1,n}；

S3-3, obtaining the height H between the upper bottom of each layer and the bottom of the channel according to the actual layering_{1,2,3,...,n-1,n}And calculating the width B of the upper bottom of each layer_{1,2,3,...,n-1,n}The calculation formula is

And calculating the width B of the upper bottom edge of the deposit_{Silting up}The calculation formula is

Wherein s is the slope ratio of the side slope of the original channel, and b is the width of the channel bottom of the original channel;

s3-4, obtaining the channel bottom coefficient K according to the actual situation of the channel section_B；

S3-5, calculating the layered flow Q of each layer_{1,2,3,...,n-1,n}The formula for n is 1

The calculation formula of n is more than or equal to 2

Flow Q corresponding to the same sedimentation layer_{Silting up}The corresponding calculation formula is

S3-6, the formula for accurately measuring the flow after removing the siltation is Q ═ Q₁+Q₂+...+Q_n-1+Q_n-Q_{Silting up}+Q_{Surface layer} (8)。

2. The automated and accurate flow metering method for a silt-laden channel of claim 1, which is characterized in that: for the channel bottom width b less than or equal to 25m, the number of layers is n less than or equal to 4.

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