Rapid calculation method and device for on-way fluctuation of restrictive long approach channel

Abstract

The invention relates to a rapid calculation method and device for on-way fluctuation of a restrictive long approach channel, and the method comprises the steps: obtaining a fluctuation period after water release of an approach channel ship lock based on a theoretical period calculation formula suitable for the restrictive long approach channel, and fitting a correction coefficient through the maximum amplitude at different water levels, and respectively constructing attenuation formulas of fluctuations caused by ship lock sluicing along with time and propagation distance changes, and finally establishing an approach channel fluctuation process calculation formula after ship lock sluicing by combining an attenuation sine function based on the space-time attenuation formula to obtain restrictive long approach channel on-way fluctuations. According to the method, the water level fluctuation caused by ship lock operation can be rapidly and accurately calculated, and it is ensured that large ships can pass safely.

Description

Technical Field

[0001] The present invention belongs to the field of waterway hydraulics, and particularly relates to a rapid calculation method and device for the along - course fluctuations of a restricted long approach channel. Background Art

[0002] With the growth of water transportation trade volume, the traffic density of the inland waterway network has been continuously rising, and the freight volume of inland waterway shipping has increased explosively. To better meet the demand for the growth of inland waterway shipping freight, inland waterway cargo ships have gradually become larger.

[0003] The enlargement of ships will inevitably lead to an increase in the draft depth of ships. The original designed approach channel is suitable for smaller ship types. To ensure the safe navigation of large ships, it is necessary to ensure that the water - level fluctuations caused by the filling and emptying of the ship lock meet the draft requirements of large ships. The fluctuation amplitudes of the ship lock filling and emptying are different at different water levels. When the water level is low, the fluctuation trough value may not meet the ship draft depth requirements, resulting in the risk of the ship touching the bottom. Therefore, accurately calculating the water - level fluctuations in the approach channel after the ship lock operation and giving early warnings in time for situations that do not meet the safe navigation requirements are important supports for ensuring the safe and efficient operation of the waterway. At present, there are few relevant studies on the fluctuation calculation of restricted long approach channels under the influence of the unsteady flow of ship lock drainage. Usually, numerical simulation is used to obtain the fluctuation data. The accuracies of different numerical simulation methods are different, but the calculation of numerical simulation methods is usually time - consuming and the calculation efficiency is low. Summary of the Invention

[0004] The first object of the present invention is to overcome the deficiencies in the prior art and provide a rapid calculation method for the along - course fluctuations of a restricted long approach channel, which can calculate the fluctuation process in the approach channel after the ship lock operation in a timely and accurate manner and ensure the navigation safety in the approach channel.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A rapid calculation method for the along - course fluctuations of a restricted long approach channel, the method comprising:

[0007] Obtain the length L and water depth h of the approach channel, and calculate the fluctuation period after the ship lock drains water based on the formula where is the acceleration due to gravity; g

[0008] Obtain the maximum flow rate Q corresponding to the ship lock draining water max and the width B of the approach channel, and calculate the fluctuation amplitude correction coefficient obs by combining the measured maximum wave amplitude A ;

[0009] Construct an exponential decay model of the fluctuations caused by the ship lock draining water varying with time during the propagation process , where υ is the kinematic viscosity of the water flow and t is the time; the value of the attenuation coefficient k in the formula is calibrated based on the measured data;

[0010] Construct an attenuation model of the fluctuation amplitude caused by the discharge of the lock varying with the propagation distance x ;

[0011] Construct a calculation model of the fluctuation process in the approach channel after the lock discharges water , and after substituting the obtained data, the fluctuation process in the approach channel is obtained ; In the formula is the fluctuation angular frequency, which is converted based on the fluctuation period Conversion.

[0012] In some embodiments of the present invention, the measured maximum wave amplitude A obs is obtained by setting water level fluctuation measurement points in the approach channel, measuring the water level fluctuation process after the lock discharges water, and obtaining the measured maximum wave amplitude.

[0013] In some embodiments of the present invention, when calculating the correction coefficient α, the maximum wave amplitudes at different water levels in the approach channel are measured, and regression analysis is performed on the multiple measurement results to obtain the correction coefficient. Further, the measurement points for measuring the wave amplitude at least include the water level fluctuation measurement points set at the lock head, and the maximum wave amplitudes at different water levels measured at the lock head are used to fit the correction coefficient; in the case of multiple measurement points, the data of other measurement points can be used to verify the accuracy of the formula calculation results.

[0014] In some embodiments of the present invention, the attenuation coefficient k is obtained by fitting based on multiple sets of measured data.

[0015] In some embodiments of the present invention, the propagation distance x is a normalized propagation distance, and the normalized propagation distance is the ratio of the current propagation distance to the length of the approach channel.

[0016] In some embodiments of the present invention, the method further includes a judgment process for a restrictive long approach channel:

[0017] Set water level fluctuation measurement points in the approach channel to obtain the water level fluctuation process;

[0018] Based on the monitored water level fluctuation process data, determine the measured fluctuation period based on spectrum analysis;

[0019] Calculate the theoretical main period based on the length L and water depth h of the channel , when the error between the measured fluctuation period and the theoretical main period ≤ 5%, it is determined that this approach channel is a restrictive long approach channel.

[0020] In some embodiments of the present invention, the setting positions of the measurement points include the lower lock head of the lock, the middle of the approach channel, and the end of the approach channel.

[0021] The second object of the present invention is to provide a computer device, including a memory, a processor, and a computer program stored on the memory, and the processor executes the computer program to implement the steps of the above method.

[0022] The third object of the present invention is to provide a computer-readable storage medium, on which a computer program / instructions are stored, and when the computer program / instructions are executed by a processor, the steps of the above method are implemented.

[0023] The fourth object of the present invention is to provide a computer program product, including a computer program / instructions, and when the computer program / instructions are executed by a processor, the steps of the above method are implemented.

[0024] The wave calculation method proposed by the present invention is specifically aimed at restrictive long approach channels. It can accurately reflect the wave amplitude and time-varying conditions according to different water level conditions, providing reliable support under different navigation conditions. Using the method of the present invention to calculate waves avoids the real-time analysis of massive data in prototype monitoring and the computational time-consuming required for numerical simulation, thus greatly improving the calculation efficiency of waves along the approach channel and meeting the technical requirements of accurate and rapid wave calculation. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the setting position of the water level observation points in the embodiment of the present invention, and the values in the figure are the bottom elevations (m).

[0026] Figure 2 It is a comparison chart of the maximum wave height calculated by the formula and the maximum wave height calculated by the numerical model in the embodiment of the present invention.

[0027] Figure 3 It is a comparison between the measured wave results and the formula calculation results in the embodiment of the present invention. Detailed Embodiments

[0028] The following further describes the present invention with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0029] The "restrictive long approach channel" is defined as follows:

[0030] In the present invention, the restrictive long approach channel refers to an approach channel that satisfies the following physical and hydraulic characteristics:

[0031] (1) A longitudinal water area located between the lock head and the entrance area, and simultaneously affected by the stable water level jointly under the filling and discharging of the lock head and the mainstream at the entrance;

[0032] (2) The wave type is a low-frequency long wave, caused by the slow filling and discharging of the lock, and the period is generally greater than 10 minutes;

[0033] (3) The water depth and the wavelength satisfy the shallow water wave condition h << λ, that is, λ is significantly greater than the water depth and width of the approach channel;

[0034] (4) The geometry of the channel is approximately long, straight and regular in shape, and the length L usually exceeds 1000 meters;

[0035] (5) There is an approximate relationship among the fluctuation period, the channel length, and the water depth: , that is, the complete time required for the excited wave to travel back and forth.

[0036] If the measured main period of the fluctuation obtained through spectral analysis is close to the calculated value (the error does not exceed 5%), it can be considered to meet the conditions of the "restricted long approach channel", and the fast fluctuation calculation method described in the present invention is applicable.

[0037] Taking the fluctuation caused by the discharge of the No. 2 lock of a certain approach channel as an example, the technical solution of the present invention is further elaborated with the attached drawings. A method for calculating the fluctuation of a restricted long approach channel described in the present invention specifically includes the following steps:

[0038] (1) Characteristic parameters of the approach channel:

[0039] The approach channel is 140 m wide, with a total length of 3570 m, an aspect ratio of about 25:1, a bottom elevation z0 = 34.5 m, a water level z1 = 39 m, a working head of the lock of 27 m, and a corresponding maximum discharge Q max = 614 m 3 / s. Under typical discharge conditions, the main period of the fluctuation is about 30 to 36 minutes. The geometry of the approach channel is approximately a long, straight and regular channel. The main river channel is about 680 m wide. The water level in the approach channel mouth area is restricted by the main river channel water level. After the lock discharge fluctuation propagates to the mouth area, it is affected by the main river water level and reflects. This approach channel meets the low-frequency long-wave conditions.

[0040] (2) Three prototype water level observation points are set up, which are located at the lower head of the No. 2 lock, the middle of the approach channel, and the mouth area respectively, as Figure 1 shown. After measuring the water level fluctuations at the three measuring points after the No. 2 lock discharges water. Measuring the maximum fluctuations at different approach channel water levels, and performing regression analysis on the results of multiple measurements to obtain a correction coefficient α = 0.85. Under the condition of an approach channel water level of 39 m and a working head of 27 m, the fluctuation amplitude near the downstream mooring pier of the No. 2 lock is 0.45 m, and the fluctuation amplitude near the bridge is also 0.45 m; under the condition of an approach channel water level of 42 m and a working head of 24 m, the fluctuation amplitude near the downstream mooring pier of the No. 2 lock is 0.37 m, and the fluctuation amplitude near the bridge is 0.35 m.

[0041] Calculate the fluctuation amplitude A according to the maximum discharge of the lock discharge:

[0042] (1)

[0043] According to the above analysis and data pattern, the calculation formula for the main period of the approach channel fluctuations can be obtained:

[0044] (2)

[0045] In the formula, L is the length of the approach channel, h is the water depth of the approach channel, and the bottom elevation is calculated as 34.5 m.

[0046] The fluctuation periods calculated by the formula under different downstream water level conditions and the periods obtained from the spectrum analysis are shown in Table 1. The results show that the fluctuation periods calculated by the formula have high accuracy.

[0047] Table 1 Calculation results of the fluctuation periods corresponding to different downstream approach channel water levels and the results calculated by the formula

[0048]

[0049] Generally, the attenuation rate of the fluctuations with time is related to the wavelength. In addition, for gravity long waves, its attenuation rate is also related to the gravitational acceleration, water depth, and water surface width. Therefore, the coefficient β in the following formula is a function of these variables. Through data regression analysis, the exponential attenuation law of the fluctuation amplitude with time is:

[0050] (3)

[0051] In the formula, β is the attenuation rate coefficient, t is the time, k is the attenuation coefficient, υ is the kinematic viscosity of the water flow, L is the length of the approach channel, g is the gravitational acceleration, h is the water depth of the approach channel, and B is the width of the approach channel.

[0052] By fitting the exponential law of the fluctuations decaying with time with multiple groups of measured data, the attenuation coefficient k = 105 is obtained. After substituting it into the above formula, the attenuation rate coefficients β of the fluctuation amplitudes under different downstream water levels are shown in Table 2. When the downstream water level in the prototype monitoring data of the approach channel water level is 39.94, the amplitude attenuation rate coefficient is 0.00023, and the calculated value by the formula is 0.00020; when the downstream water level is 40.53 m, the measured amplitude attenuation rate coefficient is 0.00018, and the calculated value by the formula is 0.00018, and the two are exactly the same. This shows that the attenuation process of the fluctuations with time can be accurately calculated using formula (3).

[0053] Table 2 Calculation results of the formula for the attenuation rate coefficient of the approach channel fluctuations with time under different downstream approach channel water level conditions

[0054]

[0055] Judging from the calculation results and the prototype monitoring data, the approach channel fluctuations are typical sine curves with the amplitude decaying with time and position, and its process can be described by the following formula:

[0056] (4)

[0057] Among them, is the amplitude of fluctuation, which includes the variation of amplitude along the way.

[0058] The fluctuation caused by the sluice discharge of the ship lock also decreases with the increase of the propagation distance. The variation of amplitude along the way can be expressed by the following formula:

[0059] (5)

[0060] In the formula, α is the correction coefficient, and x is the ratio of the different positions L1 in the approach channel to the total length L of the approach channel:

[0061] x = L1 / L (6)

[0062] is the angular frequency of the fluctuation process and can be calculated by the following formula:

[0063] (7)

[0064] From the above formulas and the coefficient values, the fluctuation process when the No. 2 ship lock discharges water alone is:

[0065] (8)

[0066] In the formula, B is the width of the approach channel, taking 140 m, H is the working head of the ship lock, h is the depth of the approach channel, x is the ratio of the distance downstream of the mooring pier to the distance from the mooring pier to Miaozui (taking 3200 m), υ is the kinematic viscosity of the water flow, taking 10 -6 , and L is the total length of the approach channel, taking 3570 m.

[0067] Figure 2 The comparison between the calculated values and the measured values of the maximum fluctuation at the lock head under different maximum discharge rates of the ship lock discharge is given, Figure 3 is the prototype monitoring and formula calculation results of the fluctuation process near the mooring pier and the bridge in the approach channel. Figure 3 The comparison results shown in it indicate that the absolute error of the wave height in most working conditions calculated by the formula does not exceed 5 cm, and the maximum error in individual cases is 8 cm.

Claims

1. A rapid calculation method for the fluctuations along a restricted long approach channel, characterized in that, The method includes: Obtain the approach channel length L and water depth h, and based on the formula Calculate the fluctuation period after the lock discharges water , where g is the acceleration due to gravity; Obtain the maximum flow rate Q corresponding to the discharge of the ship lock max and the width B of the approach channel, and combine with the measured maximum wave amplitude A obs Calculate the wave amplitude correction coefficient ; Construct an exponential decay model of the fluctuations caused by the discharge of the ship lock varying with time during the propagation process , where υ is the kinematic viscosity of the water flow and t is the time; calibrate the value of the decay coefficient k in the formula based on the measured data Construct an attenuation model for the variation of the fluctuation amplitude caused by the discharge of the ship lock with the propagation distance x ; Construct a calculation model for the fluctuation process of the approach channel after the ship lock discharges water , and obtain the fluctuation process of the approach channel after substituting the obtained data ; where is the fluctuation angular frequency, which is converted based on the fluctuation period .

2. The method according to claim 1, characterized in that The measured maximum wave amplitude A obs is obtained by setting water level fluctuation measurement points in the approach channel, measuring the water level fluctuation process after the ship lock discharges water, and obtaining the measured maximum wave amplitude.

3. The method according to claim 1, characterized in that, When calculating the correction coefficient α, measure the maximum wave amplitude at different water levels in the approach channel, perform regression analysis on the multiple measurement results, and obtain the correction coefficient.

4. The method according to claim 1, characterized in that The attenuation coefficient k is obtained by fitting based on multiple groups of measured data.

5. The method according to claim 1, characterized in that The propagation distance x is a normalized propagation distance, and the normalized propagation distance is the ratio of the current propagation distance to the length of the approach channel.

6. The method according to claim 1, wherein The method further includes a judgment process for a restrictive long approach channel: Set water level fluctuation measurement points in the approach channel to obtain the water level fluctuation process; Based on the monitored water level fluctuation process data, determine the measured fluctuation period based on spectrum analysis; Calculate the theoretical main period based on the channel length L and water depth h When the error between the measured fluctuation period and the theoretical main period ≤ 5%, it is determined that the approach channel is a restricted long approach channel.

7. The method according to claim 2 or 6, characterized in that The setting positions of the measurement points include the lower lock head of the ship lock, the middle of the approach channel, and the end of the approach channel.

8. A computer device, comprising a memory, a processor, and a computer program stored on the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having computer programs / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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