Correction method for calculation of movement track of flip water tongue and application of correction method
By introducing a correction coefficient and physical model experiments into the projectile motion formula, the problems of complex and costly calculation of the trajectory of the jet stream were solved, and a simplified and reasonable trajectory calculation was achieved, which improved the flexibility and economy of engineering design.
Patent Information
- Application Number
- CN202511079732.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-01
- Publication Date
- 2025-11-18
AI Technical Summary
In the existing technology, the trajectory calculation method for the jet of water is complex and costly, and there is a lack of simple and reasonable calculation methods, which makes it difficult to meet the economic and flexibility requirements of engineering applications.
Based on the formula for oblique projectile motion, the trajectory of the water tongue is corrected by adding a correction coefficient. Taking into account factors such as air resistance and water body breakage, the upper and lower edge water tongue trajectories are corrected using the drag coefficient and the angle coefficient, and the rationality is verified through physical model experiments.
The process of calculating the water tongue trajectory has been simplified, which has improved the flexibility and rationality of the design of the jet flow energy dissipation structure and reduced the calculation cost.
Smart Images
Figure CN120974972A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of flip bucket energy dissipation of water discharge structures, and particularly relates to a correction method for calculating the trajectory of a flip bucket water jet and application thereof. BACKGROUND
[0002] Flip bucket energy dissipation is a common energy dissipation method for large-scale water conservancy projects, aiming to avoid water flow directly impacting the bottom plate of the energy dissipator by shooting water from the air into the downstream energy dissipator, and the core of the design of the flip bucket water jet trajectory control is the trajectory control of the flip bucket water jet. In the engineering design stage, the trajectory of the flip bucket water jet is generally predicted by theoretical calculation, numerical simulation or model test method, and the research results have certain reference value. However, in the above methods, the theoretical calculation formula is relatively complex, the difficulty of starting is large, the numerical simulation and model test cost is high, and the implementation needs corresponding basic support, which lacks economy and flexibility for engineering application.
[0003] Therefore, at present, there is a lack of simple and reasonable calculation method for the trajectory calculation of the flip bucket water jet in the project. SUMMARY
[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a correction method for calculating the trajectory of a flip bucket water jet and application thereof. On the basis of the oblique throw motion formula, a reasonable water jet trajectory is drawn by increasing a correction coefficient.
[0005] In order to achieve the above technical purpose, the theoretical analysis of the present application is as follows:
[0006] 1. Only considering gravity, the air movement of the flip bucket water jet is oblique throw movement, when calculating its trajectory, the oblique velocity can be decomposed into horizontal and vertical velocities, the movement coordinates of the water body at different times are solved respectively, and the movement positions of the water body at different times are connected to obtain the movement trajectory of the water jet.
[0007] 2. The air movement trajectory of the water jet can be divided into an ascending segment, a highest point and a descending segment.
[0008] 3. In the actual environment, the movement of the water jet in the air is in a non-ideal state, air resistance and water jet fragmentation are two factors that change the actual movement trajectory of the water jet, so the two points can be considered for correction by selecting appropriate parameters to adjust the ideal movement trajectory of the water jet to a reasonable trajectory.
[0009] 4. In engineering application, the water depth is thick, and the air trajectory of the water jet can be distinguished as an obvious upper edge and a lower edge, and the correction of the upper and lower edge water jet trajectories is also different.
[0010] 5. For the upper edge of the water body, in the upward section of the jet, the water flow is relatively stable and has a high velocity because it has just left the spillway. Therefore, it is less affected by air resistance and water body breakage. Theoretically, the trajectory of the upward section of the ideal projectile motion can be referenced. After the jet passes the highest point and enters the downward section, the water flow velocity is low and can no longer support the water body to continue to rise. The water tongue begins to descend. At this time, the influence of air resistance and water body breakage gradually increases, and the resistance to be overcome is greater than that under ideal conditions. The trajectory should be lower than that of the downward section of the ideal projectile motion. At this time, it is advisable to adjust the flow velocity to modify the trajectory.
[0011] 6. For the lower edge water body, the water body is more severely broken in both the rising and falling sections of the jet. At the same time, since the lower edge water body is in contact with the bottom plate of the building in the spillway, the initial flow velocity of the jet water tongue is lower due to the influence of roughness. Considering both factors, the entire motion trajectory of the lower edge water tongue should be lower than the ideal oblique projectile motion. In this case, the trajectory can be corrected by adjusting the launching angle.
[0012] 7. Physical model tests are an important reference for the simulation of prototype engineering. According to the correction method proposed in this invention, its rationality can be verified through physical model tests.
[0013] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:
[0014] The first objective of this invention is to provide a method for correcting the calculation of the trajectory of a jet of water, comprising the following steps:
[0015] 1) Determine the initial conditions: average flow velocity V at the start of the lift, and the angle θ of the lift sill;
[0016] 2) Using the projectile motion formula, select any water body unit between the upper and lower edges of the water tongue and calculate the trajectory of the water tongue under ideal conditions. The ideal conditions are to consider only the effect of gravity and not the factors of air resistance and water body breakage.
[0017] This invention calculates the ideal projectile motion trajectory when the angle θ of the lifting platform is 0° to 50°, with an interval of 5°.
[0018] ① Decompose the average flow velocity V of the water flow into the flow velocity V in the x direction. x and the flow velocity V in the y direction y ;
[0019] ②The x-direction is horizontal, V x Keeping constant, the coordinate in the x-direction at each moment t is X = V. x *t;
[0020] ③The y-direction is the direction of gravity, V y Throughout the entire process, the gravitational acceleration g is applied. At a certain moment t during the ascent phase, the coordinate in the y-direction is Y = V.y t+0.5*g*t 2 , V y is gradually reduced to 0, V y0 = V y -gt max , t max is the highest point, at this time V y0 = 0, Y = Y max ; at a certain time t in the falling section, the coordinate Y in the y direction = Y max -0.5*g*t 2 , until the water body falls to the ground or enters the water pad; wherein the x direction to the right is positive, and the y direction upward is positive;
[0021] (4) The calculation interval of the x direction and the y direction is selected as 0.5s, and the unit body movement position at different time of 0.5s, 1.0s, 1.5s, … is calculated respectively;
[0022] (5) Connecting the movement positions at different time to form the trajectory line of the bucket-type water jet movement;
[0023] 3) Measure the upper and lower edge water jet trajectory on the model test, draw the ideal oblique throw trajectory of the water jet (also known as: theoretical calculation water jet trajectory), and the actual water jet movement trajectory of the model test;
[0024] 4) Upper edge water jet trajectory correction
[0025] Comparing the ideal oblique throw trajectory of the water jet and the actual water jet movement trajectory of the model test, it can be seen that before the water jet moves to the highest point, the upper edge trajectory of the actual water jet is basically consistent with the theoretical calculation value; after moving to the highest point, the actual water jet descending segment trajectory is lower than the theoretical calculation trajectory;
[0026] Consider using the drag coefficient V p to correct the lower edge trajectory of the theoretical calculation, assuming that the water flow is affected by the same size air resistance during the flow process, and the influence of air resistance on flow velocity is V j = V*V p ; after different coefficient comparison, it is determined that when the drag coefficient V p = 0.88, the water jet falling segment trajectory is consistent with the actual movement trajectory;
[0027] 5) Lower edge water jet trajectory correction
[0028] Comparing the ideal oblique throw trajectory of the water jet and the actual water jet movement trajectory of the model test, it can be seen that the actual water jet lower edge movement trajectory is lower than the theoretical calculation trajectory from the beginning (i.e. the beginning of the rising section);
[0029] Consider using the pick angle coefficient θ p to correct, by adjusting the calculation pick angle θ j = θ*θp ; through the comparison and selection of different coefficients, the pick angle coefficient θ is determined p = 0.83, the trajectory of the rising section and the falling section of the water tongue is more consistent with the actual motion trajectory;
[0030] 6) Select different pick angles for test verification
[0031] Different pick angles are selected for verification work, and the actual water tongue trajectory measured by the model test is compared with the corrected theoretical calculation water tongue trajectory, and the consistency is high, and the results show that the verification effect is good.
[0032] The role of the model test in the application is to verify the proposed correction method, and after verification, the correction method of the application is directly used subsequently, and numerical simulation or model test is no longer used, which is a faster and cost-saving method.
[0033] A second object of the application is to provide: an application of a correction method for calculating the trajectory of a pick-up water tongue in a pick-up energy dissipation project of a discharge structure. In practical engineering applications, the correction method calculates the trajectory of the water tongue:
[0034] ① Upper edge water tongue
[0035] The theoretically calculated water tongue trajectory is selected as the rising section of the actual motion trajectory; the resistance coefficient V is determined P = 0.88, and the complete water tongue calculation trajectory is corrected, and the falling section is selected as the falling section of the actual motion of the water tongue.
[0036] ② Lower edge water tongue
[0037] The pick angle coefficient θ is determined p = 0.83, and the complete water tongue calculation trajectory is corrected as the actual motion trajectory of the water tongue.
[0038] The application provides a correction method for the trajectory of a pick-up water tongue by a theoretical calculation method, on the basis of ideal water body oblique throwing motion (only considering gravity), the upper and lower edge trajectories of the water tongue are corrected by using resistance coefficients and pick angle coefficients respectively, and the correction method is reasonable and feasible through physical model test, the calculation process of the real water tongue trajectory is simplified, and the flexibility and rationality of the design of the pick-up energy dissipation structure are improved. BRIEF DESCRIPTION OF DRAWINGS
[0039] Figure 1 The pick-up water tongue trajectory (theoretical calculation) of different pick-up angles in the embodiment is shown in the figure;
[0040] Figure 2 The model test, the theoretical calculation pick-up water tongue trajectory (θ = 35°) in the embodiment is shown in the figure;
[0041] Figure 3Trajectory of upper edge of nappe (θ = 35°) for model test, theoretical calculation (after correction) in the example;
[0042] Figure 4 Trajectory of lower edge of nappe (θ = 35°) for model test, theoretical calculation (after correction) in the example;
[0043] Figure 5 Trajectory of nappe (θ = 20°) for model test, theoretical calculation (before correction) in the example;
[0044] Figure 6 Trajectory of upper edge of nappe (θ = 20°) for model test, theoretical calculation (after correction) in the example;
[0045] Figure 7 Trajectory of lower edge of nappe (θ = 20°) for model test, theoretical calculation (after correction) in the example. DETAILED DESCRIPTION
[0046] A correction method for calculating trajectory of nappe, the specific correction method is as follows:
[0047] First step: collate initial conditions, average flow velocity V of water flow at nappe, and nappe angle θ.
[0048] Second step: use oblique throwing motion formula to select any water unit in upper edge and lower edge of nappe, and calculate trajectory under ideal conditions (only consider gravity, and do not consider air resistance and water body breaking). In the embodiment, ideal oblique throwing trajectories when nappe angle θ is 0°-50° (interval angle is 5°) are calculated, and 35° nappe angle used in JX hydropower station project is taken as an example for calculation demonstration.
[0049] 1) The average flow velocity V of water flow at nappe is decomposed into flow velocity V x x in x direction and flow velocity V y y in y direction, V x x = 20.43 m / s and V y y = 24.35 m / s; at t = 0, X = 0 and Y = 3327.7;
[0050] 2) The x direction is horizontal, V x x remains unchanged, and the coordinate in x direction at each motion time t is X = V x x * t.
[0051] 3) The y direction is gravity direction, V y y is affected by gravity acceleration g all the way, and the coordinate in y direction at a time t in the rising section is Y = V y y * t + 0.5 * g * t 2 , at the same time, V y y gradually decreases to 0, and V y0 y = Vy -gt max , t max At the highest point, V y0 =0, Y=Y max At a certain time t during the descent segment, the coordinate in the y-direction is Y = Y max -0.5gt 2 The water continues until it reaches the ground or enters the water cushion; where x-direction to the right is positive, and y-direction upwards is positive.
[0052] 4) The calculation interval for the x and y directions is set to 0.5s. The unit movement position at 0.5s, 1.0s, 1.5s... is calculated respectively (as shown in Table 1 below);
[0053] Table 1. Calculation of the trajectory of the water jet (θ=35°, V=31.78m / s)
[0054]
[0055]
[0056] 5) Connect the positions of the water jet at different times to form the trajectory line of the jet's movement (e.g., Figure 1 (As shown).
[0057] Step 3: Measure the water jet trajectories at the upper and lower edges of the model test, and plot the ideal projectile motion trajectory of the water jet (i.e., the theoretically calculated water jet trajectory). The actual water jet motion trajectory of the model test is shown below. Figure 2 .
[0058] Step 4: Correction of the upper edge water tongue trajectory
[0059] observe Figure 2 It can be seen that before the water tongue reaches its highest point, the actual trajectory of the upper edge of the water tongue is basically consistent with the theoretical calculation value; after reaching the highest point, the actual trajectory of the descending segment of the water tongue is lower than the theoretical calculation trajectory, which is consistent with the above theoretical analysis.
[0060] Consider using the drag coefficient V p The theoretically calculated lower edge trajectory is corrected by assuming that the water flow is affected by the same amount of air resistance throughout the flow process, and the effect of air resistance on the flow velocity is V. j =V*V p The motion trajectory of the water flow considering resistance was plotted.
[0061] After comparing different coefficients, the drag coefficient V was determined. p When the value is 0.88, the trajectory of the water tongue during its downward fall is relatively consistent with the actual trajectory. Figure 3 ).
[0062] Step 5: Correction of the lower edge water tongue trajectory
[0063] Observation Figure 2 It can be seen that the actual water tongue lower edge trajectory is lower than the theoretical calculation trajectory from the beginning (i.e., the beginning of the rising section), which is consistent with the theoretical analysis.
[0064] Consider using the pick angle coefficient θ p Make corrections by adjusting the calculation pick-up angle θ j = θ * θ p , and draw the corrected water flow lower edge trajectory.
[0065] After comparing different coefficients, it is determined that when the pick angle coefficient θ p = 0.83, the trajectories of the water tongue rising section and the falling section are more consistent with the actual movement trajectory. Figure 4 ).
[0066] Step 6: Select different pick angles for test verification
[0067] Select a 20° pick angle for verification work, Figure 5 The water tongue trajectory before correction, Figure 6 , Figure 7 The corrected water tongue trajectory comparison, the results show that the verification effect is good, the correction method proposed in this embodiment is reasonable and reliable.
[0068] Step 7: Engineering application
[0069] In actual engineering application, the movement trajectory of the water tongue is calculated by the method proposed in this embodiment.
[0070] (1) Upper edge water tongue
[0071] Select the theoretical calculation water tongue trajectory as the rising section of the actual movement trajectory; determine the resistance coefficient VP = 0.88, and correct to obtain the complete water tongue calculation trajectory, and select the falling section as the falling section of the actual movement of the water tongue.
[0072] (2) Lower edge water tongue
[0073] Determine the pick angle coefficient θp = 0.83, and correct to obtain the complete water tongue calculation trajectory as the actual movement trajectory of the water tongue.
Claims
1. A correction method for calculating the trajectory of a jet of water, characterized in that, Includes the following steps: 1) Determine the initial conditions: average flow velocity V at the start of the lift, and the lift angle θ; 2) Using the projectile motion formula, select any water body unit between the upper and lower edges of the water tongue and calculate the trajectory under ideal conditions. The ideal conditions are to consider only the effect of gravity and not the factors of air resistance and water body breakage. 3) Measure the trajectories of the water tongue at the upper and lower edges of the model test, and draw the ideal projectile motion trajectory of the water tongue and the actual water tongue motion trajectory of the model test; 4) Correction of the upper edge water tongue trajectory Comparing the ideal projectile motion trajectory of the water tongue with the actual water tongue motion trajectory of the model test, it can be seen that before the water tongue reaches its highest point, the trajectory of the upper edge of the actual water tongue is basically consistent with the theoretical calculation value; after reaching the highest point, the trajectory of the actual water tongue in the descending segment is lower than the theoretical calculation trajectory. Using the drag coefficient V p The theoretically calculated lower edge trajectory is corrected by assuming that the water flow is affected by the same amount of air resistance throughout the flow process, and the effect of air resistance on the flow velocity is V. j =V*V p ; 5) Correction of the lower edge water tongue trajectory Comparing the ideal projectile motion trajectory of the water jet with the actual water jet trajectory from the model test, it can be seen that the actual lower edge trajectory of the water jet is lower than the theoretically calculated trajectory from the beginning of the rising phase. Therefore, considering the use of the tilt angle coefficient θ... p Make corrections; 6) Select different bend angles for experimental verification. Different angles of the sill were selected for verification. The actual water tongue trajectory measured by the model test was compared with the corrected theoretical water tongue trajectory. The results showed a high degree of agreement, indicating that the verification effect was good.
2. The correction method for calculating the trajectory of a jet of water as described in claim 1, characterized in that, In step 2), the ideal projectile motion trajectory was calculated when the angle θ of the lifting platform was 0° to 50°, with an interval of 5°.
3. The correction method for calculating the trajectory of a jet of water as described in claim 2, characterized in that, In step 2), the calculation method for the ideal projectile motion trajectory is as follows: ① Decompose the average flow velocity V of the water flow into the flow velocity V in the x direction. x and the flow velocity V in the y direction y ; ②The x-direction is horizontal, V x Keeping constant, the coordinate in the x-direction at each moment t is X = V. x *t; ③The y-direction is the direction of gravity, V y Throughout the entire process, the gravitational acceleration g is applied. At a certain moment t during the ascent, the coordinate in the y-direction is Y = V. y *t+0.5*g*t 2 Meanwhile, V y Gradually decrease until 0, V y0 =V y -gt max , t max At the highest point, V y0 =0, Y=Y max At a certain time t during the descent segment, the coordinate in the y-direction is Y = Y max -0.5gt 2 The water continues until it reaches the ground or enters the water cushion; where x-direction to the right is positive, and y-direction upwards is positive. ④ The calculation interval for the x and y directions is set to 0.5s, and the position of the unit body at different times is calculated respectively; ⑤ Connect the positions of the water jet at different times to form the trajectory line of the water jet.
4. The correction method for calculating the trajectory of a jet of water as described in claim 3, characterized in that, In step 4), the drag coefficient V is determined by comparing different coefficients. p When the value is 0.88, the trajectory of the water tongue falling segment is relatively consistent with the actual trajectory.
5. The correction method for calculating the trajectory of a jet of water as described in claim 4, characterized in that, In step 5), the tilt angle coefficient θ is determined by comparing different coefficients. p When the value is 0.83, the trajectories of the rising and falling segments of the water tongue are in good agreement with the actual trajectory.
6. The application of the modified method according to any one of claims 1-5 in the energy dissipation project of the spillway structure.
7. The application according to claim 6, characterized in that, In practical engineering applications, the correction method calculates the trajectory of the water jet: ① Upper edge water tongue The theoretically calculated trajectory of the water jet is selected as the ascending segment of the actual motion trajectory; the drag coefficient V is determined. P =0.88, corrected to obtain the complete calculated trajectory of the water tongue, and its descending segment is selected as the descending segment of the actual movement of the water tongue; ② Lower edge water tongue Determine the angle coefficient θ p =0.83, and the corrected value is used to obtain the complete calculated trajectory of the water tongue as the actual motion trajectory of the water tongue.