Rapid calculation method and equipment for fluctuation along restrictive long approach channel

Abstract

The present invention relates to a method and apparatus for rapidly calculating fluctuations along a restricted long approach channel. The method comprises obtaining the fluctuation period of the approach channel after the release of water from a ship lock based on a theoretical period calculation formula applicable to the restricted long approach channel. Using the maximum amplitude fitting correction coefficient at different water levels, attenuation formulas are constructed to respectively calculate how the fluctuation caused by the ship lock release changes with time and propagation distance. Finally, based on the spatiotemporal attenuation formula and incorporating a decaying sine function, a calculation formula for the fluctuation process of the approach channel after the ship lock release is established to obtain the fluctuations along the restricted long approach channel. The method of the present invention can quickly and accurately calculate the water level fluctuations caused by ship lock operation, ensuring the safe passage of large ships.

Description

Technical Field

[0001] The invention belongs to the field of waterway hydraulics, and in particular relates to a method and device for quickly calculating the fluctuation along a restrictive long approach channel. Background Art

[0002] With the growth of waterborne trade, the traffic density of inland waterway networks has continued to rise, and inland waterway freight volume has exploded. To better meet the growing demand for inland waterway freight, inland waterway cargo ships have gradually become larger.

[0003] The increase in ship size inevitably leads to an increase in ship draft. The original design of the pilot channel was adapted to smaller ships. To ensure the safe navigation of large ships, it is necessary to ensure that the fluctuation of the channel water level caused by the filling and discharge of the lock meets the draft requirements of large ships. The fluctuation amplitude of the lock filling and discharge water varies at different water levels. When the water level is low, the fluctuation trough may not meet the ship draft requirements, causing the risk of the ship hitting the bottom. Therefore, accurately calculating the water level fluctuation of the pilot channel after the lock is operated and timely warning of situations that do not meet the safe navigation requirements are important supports for ensuring the safe and efficient operation of the waterway. Currently, there is little research on the fluctuation calculation of restrictive long pilot channels under the influence of non-steady flow of lock discharge water. Numerical simulation is usually used to obtain fluctuation data. The accuracy of different numerical simulation methods varies, but the calculation of numerical simulation methods is usually time-consuming and inefficient. Summary of the Invention

[0004] The first purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for quickly calculating the fluctuations along a restrictive long approach channel, which can timely and accurately calculate the fluctuation process in the approach channel after the operation of the lock, thereby ensuring navigation safety in the approach channel.

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

[0006] A method for quickly calculating fluctuations along a restrictive long approach channel, the method comprising:

[0007] Obtain the length L and water depth h of the pilot channel based on the formula Calculate the fluctuation period after the lock releases water ,in g is the acceleration due to gravity;

[0008] Get the maximum flow Q corresponding to the lock release max and the width of the pilot channel B, combined with the measured maximum amplitude A obs Calculate the fluctuation amplitude correction factor ;

[0009] Construct an exponential decay model for the time-varying propagation of the waves caused by the lock discharge , where υ is the kinematic viscosity of the water flow and t is the time; the value of the attenuation coefficient k in the calibration formula is determined based on the measured data;

[0010] Construct an attenuation model for the fluctuation amplitude caused by the lock discharge as the propagation distance x changes ;

[0011] Constructing a computational model for the navigation channel fluctuation process after the ship lock releases water , after substituting the acquired data, the pilot channel fluctuation process is obtained Where is the angular frequency of the fluctuation, based on the fluctuation period Conversion.

[0012] In some embodiments of the present invention, the measured maximum amplitude A obs The method for obtaining it is to set up water level fluctuation measuring points in the pilot channel, measure the water level fluctuation process after the ship lock releases water, and obtain the measured maximum amplitude.

[0013] In some embodiments of the present invention, the correction coefficient α is calculated by measuring the maximum amplitude at different pilot channel water levels, and performing regression analysis on the multiple measurement results to obtain the correction coefficient. Furthermore, the amplitude measurement points include at least a water level fluctuation measurement point located at the gate head, and the correction coefficient is fitted using the maximum amplitude at different water levels measured at the gate head. If multiple measurement points are used, the accuracy of the calculation results can be verified using data from other measurement points.

[0014] In some embodiments of the present invention, the attenuation coefficient k is obtained based on fitting of 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 a ratio of a current propagation distance to a pilot channel length.

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

[0017] Set up water level fluctuation measuring points in the pilot channel to obtain the water level fluctuation process;

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

[0019] 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 is ≤5%, the pilot channel is determined to be a restrictive long pilot channel.

[0020] In some embodiments of the present invention, the measurement points are set at locations including the lower head of the ship lock, the middle of the pilot channel, and the end of the pilot channel.

[0021] A second object of the present invention is to provide a computer device comprising a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0022] A third object of the present invention is to provide a computer-readable storage medium having a computer program / instruction stored thereon, which implements the steps of the above method when the computer program / instruction is executed by a processor.

[0023] A fourth object of the present invention is to provide a computer program product, comprising a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0024] The proposed fluctuation calculation method is specifically designed for restrictive, narrow pilot channels. It accurately reflects the amplitude and time-varying nature of fluctuations based on varying water level conditions, providing reliable support under diverse navigation conditions. Using this method to calculate fluctuations avoids the time-consuming computational effort required for real-time analysis and numerical simulation of massive data from prototype monitoring, significantly improving the efficiency of calculating fluctuations along the pilot channel and meeting the technical requirements for accurate and rapid fluctuation calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the location of the water level observation point in an embodiment of the present invention, where the value is the bottom elevation (m).

[0026] Figure 2 3 is a comparison chart of the maximum wave height calculated by the formula and the maximum wave height calculated by the numerical model in an embodiment of the present invention.

[0027] Figure 3 The figure is a comparison between the actual measurement results of the fluctuations in the embodiment of the present invention and the calculation results of the formula. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0029] The definition of "restricted long approach channel" is as follows:

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

[0031] (1) The longitudinal water area between the ship lock head and the gate area, which is affected by the stable water level under the influence of the filling and discharge of water at the lock head and the main flow at the gate;

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

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

[0034] (4) The channel geometry is approximately long, straight and regular, with a length L usually exceeding 1000 meters;

[0035] (5) The fluctuation period satisfies the approximate relationship with the channel length and water depth: , which is the complete time required for the excitation wave to propagate back and forth.

[0036] If the measured fluctuation main period obtained by spectrum analysis is close to the calculated value (the error does not exceed 5%), it can be regarded as meeting the "restrictive long approach channel" condition and the rapid fluctuation calculation method described in the present invention is applicable.

[0037] This example uses the fluctuation caused by the release of the No. 2 ship lock of a certain approach channel as an example, and the accompanying drawings further illustrate the technical solution of the present invention. The fluctuation calculation method of a restrictive long approach channel described in the present invention specifically includes the following steps:

[0038] (1) Characteristic parameters of pilot channel:

[0039] The pilot channel is 140m wide and 3570m long, with a length-to-width ratio of about 25:1, a bottom elevation of z0=34.5m, a water level of z1=39m, and a working head of 27m, corresponding to a maximum discharge flow of Q max =614m 3 / s. Under typical discharge conditions, the main period of fluctuation is approximately 30 to 36 minutes. The approach channel geometry resembles a long, straight, regular channel, with a main channel width of approximately 680 meters. The water level at the approach channel entrance is constrained by the main channel water level. After the lock discharge fluctuations propagate to the entrance area, they are affected by the mainstream water level and reflected. This approach channel meets the low-frequency long wave conditions.

[0040] (2) Three prototype water level observation points were set up, located at the lower gate of No. 2 ship lock, the middle of the navigation channel and the entrance area, such as Figure 1 As shown in the figure, water level fluctuations at three measuring points were measured after the release of Lock 2#. The maximum fluctuations at different water levels in the approach channel were measured. Regression analysis of the multiple measurement results yielded a correction factor α of 0.85. When the approach channel water level was 39 m, the amplitude of the fluctuation near the downstream pier of Lock 2# was 0.45 m at an applied head of 27 m, and the amplitude was also 0.45 m near the bridge. When the approach channel water level was 42 m, the amplitude of the fluctuation near the downstream pier of Lock 2# was 0.37 m at an applied head of 24 m, and the amplitude was 0.35 m near the bridge.

[0041] Calculate the fluctuation amplitude A based on the maximum discharge flow of the lock:

[0042] (1)

[0043] According to the above analysis and data rules, the calculation formula for the main period of pilot channel fluctuation can be obtained:

[0044] (2)

[0045] Where L is the length of the pilot channel, h is the water depth of the pilot channel, and the bottom elevation is 34.5m.

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

[0047] Table 1 Calculation results of fluctuation period corresponding to different downstream pilot channel water levels and calculation results of formula

[0048]

[0049] Generally, the rate at which waves decay over time is related to their wavelength. Furthermore, for long gravity waves, their decay rate is also related to gravitational acceleration, water depth, and water surface width. Therefore, the coefficient β in the following formula is a function of these variables. Data regression analysis shows that the exponential decay law of the wave amplitude over time is:

[0050] (3)

[0051] Where β is the attenuation velocity coefficient, t is time, k is the attenuation coefficient, υ is the kinematic viscosity of the water flow, L is the length of the pilot channel, g is the acceleration of gravity, h is the water depth of the pilot channel, and B is the width of the pilot channel.

[0052] By fitting multiple sets of measured data to the exponential law of fluctuation attenuation over time, we obtained an attenuation coefficient k = 105. Substituting this into the above formula, we calculated the attenuation rate coefficient β of the fluctuation amplitude at different downstream water levels, as shown in Table 2. In the pilot channel water level prototype monitoring data, when the downstream water level was 39.94 m, the amplitude attenuation rate coefficient was 0.00023, and the calculated value was 0.00020. When the downstream water level was 40.53 m, the measured amplitude attenuation rate coefficient was 0.00018, and the calculated value was 0.00018, which is completely consistent. This shows that formula (3) can accurately calculate the attenuation process of fluctuations over time.

[0053] Table 2 Calculation results of the formula for the decay rate coefficient of the approach channel fluctuation over time under different downstream approach channel water level conditions

[0054]

[0055] From the calculation results and prototype monitoring data, it can be seen that the pilot channel fluctuation is a typical sinusoidal curve with amplitude decaying with time and position. The process can be described by the following formula:

[0056] (4)

[0057] in, is the fluctuation amplitude, including the amplitude change along the process.

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

[0059] (5)

[0060] Where α is the correction coefficient, and x is the ratio of L1 at different positions of the pilot channel to L of the entire pilot channel:

[0061] x=L1 / L (6)

[0062] is the angular frequency of the wave process, which can be calculated by the following formula:

[0063] (7)

[0064] From the above formulas and coefficient values, the fluctuation process when the 2# ship lock releases water alone can be obtained as follows:

[0065] (8)

[0066] Where B is the width of the pilot channel, which is 140m, H is the water head of the ship lock, h is the water depth of the pilot channel, x is the ratio of the downstream distance of the pier to the distance from the pier to the temple (taken as 3200m), υ is the kinematic viscosity of the water, which is 10 -6 , L is the total length of the pilot channel, which is 3570m.

[0067] Figure 2 The comparison between the calculated and measured maximum fluctuations at the lock head under different maximum discharge rates is given. Figure 3 Prototype monitoring and formula calculation results of wave processes near the approach channel piers and bridges. Figure 3 The comparison results shown in the figure show that the absolute error of the wave height calculated by the formula for most working conditions does not exceed 5 cm, and the maximum error in some cases is 8 cm.

Claims

1. A fast calculation method for the fluctuation along the restricted long approach channel, characterized by: The method comprises: Obtain the length L and water depth h of the pilot channel based on the formula Calculate the fluctuation period after the lock releases water ,in g is the acceleration due to gravity; Get the maximum flow Q corresponding to the lock release max and the width of the pilot channel B, combined with the measured maximum amplitude A obs Calculate the fluctuation amplitude correction factor ; Construct an exponential decay model for the time-varying propagation of the waves caused by the lock discharge , where υ is the kinematic viscosity of the water flow and t is the time; the value of the attenuation coefficient k in the calibration formula is determined based on the measured data; Construct an attenuation model for the fluctuation amplitude caused by the lock discharge as the propagation distance x changes ; Constructing a computational model for the navigation channel fluctuation process after the ship lock releases water , after substituting the acquired data, the pilot channel fluctuation process is obtained Where is the angular frequency of the fluctuation, based on the fluctuation period Conversion.

2. The method according to claim 1, characterized in that The measured maximum amplitude A obs The method for obtaining it is to set up water level fluctuation measuring points in the pilot channel, measure the water level fluctuation process after the ship lock releases water, and obtain the measured maximum amplitude.

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

4. The method according to claim 1, wherein The attenuation coefficient k is obtained based on fitting of multiple sets of measured data.

5. The method according to claim 1, wherein The propagation distance x is a normalized propagation distance, which is a ratio of the current propagation distance to the pilot channel length.

6. The method according to claim 1, characterized in that The method also includes a process for determining a restrictive long approach channel: Set up water level fluctuation measuring points in the pilot channel to obtain the water level fluctuation process; Based on the monitored water level fluctuation process data, the measured fluctuation period is determined 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 is ≤5%, the pilot channel is determined to be a restrictive long pilot channel.

7. The method according to claim 2 or 6, characterized in that The measurement points are set at the lower gate of the ship lock, the middle of the pilot channel and the end of the pilot channel.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, wherein: 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 a computer program / instruction stored thereon, characterized in that: When the computer program / instruction is executed by a 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 / instruction is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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