Method for estimating flow by means of radar wave flow meter

[0077] The present invention will be further introduced below in conjunction with the drawings, but the present invention is not limited by specific embodiments.

[0078] 1. Surface velocity measurement

[0079] Such as figure 2 As shown, the radar wave flow meter generally has multiple probes. Let’s take three probes as an example. These three probes will measure three surface velocities at a certain moment, which we denote as V1, V2, and V3. , These three probes will measure multiple sets of data, which we denote as 1(V1, V2, V3), 2(V1, V2, V3),..., n(V1, V2, V3), of which 1, 2,... , N represents different moments.

[0080] 2. Calculation of synthetic surface velocity

[0081] For the three surface velocities at a certain moment, we take the first moment 1 (V1, V2, V3) as an example. We can artificially set three probes according to the height and position of each probe and the relevant conditions of the river itself. For example, the weight values ​​corresponding to the three flow rates are respectively P1, P2, and P3, where P1+P2+P3=1. Then we can get the synthetic surface velocity at this moment according to the three surface velocity, as shown in the following formula: V Combine 1 =V1*P1+V2*P2+V3*P3. In the same way, the synthetic surface velocity V at n times can be calculated In 1 , V In 2 ,..., V Close.

[0082] 3. Calculation of average flow rate

[0083] (1) Compile data

[0084] Through steps 1 and 2, we have obtained the synthesized surface velocity value (V In 1 , V In 2 ,..., V Close ), at the same time, we measured the actual average flow velocity (V Average 1 , V Average 2 ,..., V Average n ). Therefore, we have obtained n sets of average velocity and synthetic surface velocity data (V In 1 , V Average 1 ), (V In 2 , V Average 2 ), ..., (V Close , V Average n ). We organize the data into the above format.

[0085] (2) Derivation of functional relationship

[0086] With multiple sets of average flow velocity and synthetic surface flow velocity data, we can use curve fitting related principles to derive the functional relationship between the two. The present invention provides three types of functional relationships between binary linear equations, polynomial equations and exponential equations as The assumed correlation between the average flow velocity and the synthetic surface flow velocity, and then the undetermined parameters are obtained by the least square method. Take the unary linear function as an example to briefly explain this process:

[0087] It is assumed that there is a one-dimensional linear function relationship between the average velocity and the composite surface velocity, that is, the linear function V average = AV Combine +b. But the parameters a and b are to be determined. According to the principle of least square method, the measured value V Average i And calculated value V Calculate i= aV 合i The sum of squared deviations of +b is the smallest that is Φ=∑(V Average i -V Calculate i ) 2 The smallest is the optimal one-variable linear equation, that is, the most accurate basis for judging the functional relationship between the average velocity and the composite surface velocity, when ∑(V Average i -V Calculate i ) 2 At the minimum, the partial derivative of the Φ function with respect to a and b can be obtained, and the partial derivative is equal to 0 to obtain the values ​​of a and b, as shown below:

[0088] ∑2V 合i (V Average i -aV 合i -b)=0 (15)

[0089] ∑2(V Average i -aV 合i -b)=0 (16)

[0090] Then the n sets of data (V In 1 , V Average 1 ), (V In 2 , V Average 2 ), ..., (V Close , V Average n ) Bring in the above two formulas to obtain the values ​​of the parameters a and b, so that the functional relationship between the average flow velocity and the synthetic surface flow velocity is established. Of course, the two-variable linear function relation, the one-variable quadratic function relation, the one-variable cubic function relation, and the exponential function relation can be obtained in the same way.

[0091] (3) Obtain the optimal relationship

[0092] After (2) we have obtained a variety of functional relations between the two, we choose the best one as the final functional relation between the average flow velocity and the synthetic surface flow velocity. The optimal judgment basis is the mean square error of the calculation result. The formula is as follows:

[0093]

[0094] 4. Flow calculation

[0095] After step (3), we can use the synthetic surface flow rate to calculate the average flow rate V through a functional relationship, such as image 3 As shown, we are calculating the section ( image 3 Two sections are set at a certain distance upstream and downstream of the interrupted surface in the middle, and then the average of the three section areas is used as the final average section area A of the calculated section, and finally the flow value is calculated by Q=A*V.

[0096] The above description is only for the preferred embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the scope of the claims of the present invention shall fall within the protection scope of the present invention.