Method for preventing icing of open water supply trunk

Abstract

The application discloses an open water conveying trunk ice-preventing method, which prevents the water surface of the open water conveying trunk from icing through an open water conveying trunk ice-preventing device; the open water conveying trunk ice-preventing device is distributed in a matrix in the open water conveying trunk; when the transverse wind force bypasses the upper free unrestrained end, the leeward side of the upper free unrestrained end forms a Karman vortex type vibration to generate a vortex shedding frequency range; when the transverse wind force blows the upper free unrestrained end, the upper free unrestrained end generates a vertical rod self-vibration under the restraint of the restraint device to generate a vertical rod self-vibration frequency range; when the vortex shedding frequency range and the self-vibration frequency range overlap, vortex-induced resonance is generated; the air damping characteristics of the cylindrical vertical rod are changed through the restraint device to form a vibration amplification torque; the vibration amplification torque is transmitted to the lower free unrestrained end along the length direction of the cylindrical vertical rod; and vibration is generated by overcoming the hydraulic restraint of the water surface, so that the water surface of the open water conveying trunk is prevented from icing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy, in particular to an ice-preventing method for an open water conveyance main channel. BACKGROUND

[0002] The water conveyance main channel, especially the artificial water conveyance main channel, generally adopts the gravity flow mode to convey water and has the characteristics of wide channel and long distance. Such a main channel is prone to freezing due to a large latitude span.

[0003] At present, the above-mentioned main channel adopts the ice-cover water conveyance mode during the ice period and uses the ice-blocking cable as a safety measure.

[0004] However, the ice-cover water conveyance mode has the following disadvantages: first, the water conveyance efficiency during the ice period is about half of that during the normal period, and the water conveyance amount is seriously low; second, the ice cover is difficult to form in actual operation due to the flow rate and other reasons, and disasters such as ice jam and ice dam are easily formed; and third, the freezing of the main channel will bring serious safety hazards to the control facilities such as the gate and even cause permanent damage. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides an ice-preventing method for an open water conveyance main channel. The cylindrical vertical rods are arranged in the water surface of the open water conveyance main channel, so that the cylindrical vertical rods form a state of a free and unrestrained upper end, a free and unrestrained lower end, and a fixed and restrained point at a certain point in the middle. Through the vortex-induced resonance of the lateral wind force on the cylindrical vertical rods, a torque of vibration amplification is formed to overcome the vibration of the water surface caused by the hydraulic constraint and prevent the water surface from freezing.

[0006] To achieve the above-mentioned purpose, the ice-preventing method for the open water conveyance main channel designed by the present application has the following special features: the ice-preventing method prevents the water surface of the open water conveyance main channel from freezing through the ice-preventing device of the open water conveyance main channel, and the ice-preventing device of the open water conveyance main channel is distributed in a matrix in the open water conveyance main channel.

[0007] The ice-preventing device of the open water conveyance main channel includes cylindrical vertical rods vertically inserted in the water surface of the open water conveyance main channel. The lower part of the cylindrical vertical rods is located below the water surface to form a lower free and unrestrained end in the water. The upper part of the cylindrical vertical rods is located above the water surface to form an upper free and unrestrained end in the air. A fixed restraint point with adjustable height is arranged on the rod body of the cylindrical vertical rods above the water surface. The fixed restraint point is located between the upper free and unrestrained end and the lower free and unrestrained end, and a restraint device for fixing the cylindrical vertical rods is arranged at the position of the fixed restraint point.

[0008] When the lateral wind force passes around the upper free and unrestrained end, the leeward side of the upper free and unrestrained end forms a Karman vortex type vibration to generate a vortex shedding frequency range.

[0009] When the upper free end is blown by the transverse wind force, the upper free end generates a self-vibration of the vertical pole under the constraint of the constraint device, and a self-vibration frequency range is generated;

[0010] When the vortex shedding frequency range overlaps with the self-vibration frequency range, vortex-induced resonance is generated, the vortex-induced resonance is transmitted to the water surface through the damping interface of the air-water two media, and vibration is generated by overcoming the hydraulic constraint of the water surface, so that the open water supply trunk is prevented from icing.

[0011] Further, the constraint device comprises a plurality of perforations arranged radially on the cylindrical vertical pole body, a cable is inserted into the perforations, and the cable is connected with the perforations in an interference fit, both ends of the cable are connected with cable anchor fixing devices, and the two cable anchor fixing devices are located on opposite banks of the open water supply trunk.

[0012] Further, the perforations are a plurality of perforations arranged at different distances along the length direction of the cylindrical vertical pole, so as to form moments with different amplification multiples.

[0013] Further, the cable anchor fixing device is a movable fixing device.

[0014] Further, the cylindrical vertical pole is a lightweight hollow cylinder, and the top end of the cylinder is a reverse conical cylinder for receiving more wind force.

[0015] Further, the bottom end of the cylindrical vertical pole is wrapped with a self-floating body, the self-floating body is immersed in the water body, and the cylindrical vertical pole is maintained in a vertical state at all times.

[0016] Further, the self-floating body is embedded with a cylindrical lifting seat, and the lifting seat is sleeved on the bottom end of the cylindrical vertical pole.

[0017] Further, the length ratio of the upper free end to the lower free end is 7:1-9:1.

[0018] Further, the vortex shedding frequency is calculated by the following formula

[0019] f s =S t ×U / D

[0020] In the formula,

[0021] f s is the vortex shedding frequency, unit Hz,

[0022] S t is the Strohals number,

[0023] U is the transverse wind speed, unit m / s,

[0024] D is the diameter of the vertical rod, unit m;

[0025] The natural frequency of the vertical rod is calculated by the following formula

[0026]

[0027] In the formula,

[0028] f0 is the natural frequency, unit Hz,

[0029] K is the stiffness coefficient of the vertical rod,

[0030] m is the mass of the vertical rod, unit kg.

[0031] Further, the fixed constraint point is at a position of 0.4-1.4 m above the water surface, and the specific position is adjusted according to the transverse wind speed.

[0032] The advantages of the present application are:

[0033] 1. The vortex-induced resonance generation condition in the present application is: when the vortex shedding frequency range generated by the Karman vortex type vibration overlaps with the natural frequency range of the vertical rod generated by the natural vibration of the vertical rod, the generated vortex-induced resonance is transmitted to the water surface through the damping interface of the air-water body two media, and the vibration is generated by overcoming the hydraulic constraint of the water surface, thereby preventing the water surface of the open water supply channel from freezing, effectively preventing the growth of ice and ice flowers on the water surface in various ice period environments and engineering conditions, and achieving the purpose of protecting the water body from freezing. Especially for open water diversion channels, ice freezing often occurs during ice period water supply, which generally occurs during cold waves or at night, often accompanied by weather conditions such as strong winds and temperature drops. The open channel is extremely superior in terms of wind conditions and timing, which can greatly improve the efficiency of the channel water supply.

[0034] 2. The present application transmits vibration through the whole process of wind power without external power, is clean and environmentally friendly, has no effect on water quality, can ensure the safety of the channel ice period facilities, and has significant social and economic benefits;

[0035] 3. The cylindrical vertical rod in the present application is placed and anchored in a self-floating body + cable mode according to the width of the channel surface. Since the number and anchoring point height can be flexibly adjusted, and no external power is required, the cylindrical vertical rod can be flexibly configured during the ice period operation according to the specific conditions and positions of the channel.

[0036] The ice prevention method of the open water conveying trunk canal of the application utilizes the natural meteorological conditions of the open water conveying trunk canal in winter, and adopts floating and fixed type to vertically insert the cylindrical vertical rods into the water surface of the open water conveying trunk canal, so that the cylindrical vertical rods form a state of free unrestrained upper end, free unrestrained lower end and fixed constraint at a certain point in the middle, and through vortex-induced resonance of the lateral wind force on the cylindrical vertical rods, a torque of vibration amplification is formed to overcome the vibration of the water surface and prevent the water surface from freezing. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 Schematic diagram of wake structure when different Reynolds number fluid passes by non-streamlined object;

[0038] Figure 2 Schematic diagram of the cross-sectional structure of the open water conveying trunk canal to which the ice prevention method of the open water conveying trunk canal of the application is applied;

[0039] Figure 3 Schematic diagram of the planar structure of the open water conveying trunk canal to which the ice prevention method of the open water conveying trunk canal of the application is applied;

[0040] Figure 4 Schematic diagram of the structure of the cylindrical vertical rod in the ice prevention method of the open water conveying trunk canal of the application;

[0041] In the figure: open water conveying trunk canal 1, cylindrical vertical rod 2, constraint device 3, self-floating body 4;

[0042] The constraint device 3 comprises: perforation 3-1, inhaul cable 3-2, and anchor fixing device 3-3.

[0043] The self-floating body 4 comprises: elevated seat 4-1. DETAILED DESCRIPTION

[0044] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0045] In the description of the application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0046] As Figures 2 to 4As shown, taking the South-to-North Water Diversion Project's central route main canal as an example, the present invention provides an anti-icing method for open water conveyance canals. This method uses an anti-icing device in the open water conveyance canal to prevent the water surface of the open water conveyance canal 1 from freezing. The anti-icing device in the open water conveyance canal is only used during the ice-period water conveyance conditions and is distributed in a matrix in the open water conveyance canal 1.

[0047] The anti-icing device for the open water conveyance canal includes a cylindrical pole 2 vertically inserted into the water surface of the open water conveyance canal 1. The lower part of the cylindrical pole 2 is located below the water surface, forming a lower free and unrestrained end in the water. The upper part of the cylindrical pole 2 is located above the water surface, forming an upper free and unrestrained end in the air. The cylindrical pole 2 above the water surface is provided with a height-adjustable fixed constraint point. The fixed constraint point is located between the upper free and unrestrained end and the lower free and unrestrained end, and a constraint device 3 for fixing the cylindrical pole 2 is provided at the fixed constraint point.

[0048] When the lateral wind passes around the upper free and unconstrained end, the leeward side of the upper free and unconstrained end forms a Karman vortex-type vibration, generating a range of vortex shedding frequencies.

[0049] When the lateral wind blows the upper free and unrestrained end, the upper free and unrestrained end generates the pole's natural vibration under the constraint of the constraint device 3, generating the pole's natural vibration frequency range.

[0050] When the frequency range of vortex shedding overlaps with the natural frequency range, vortex-induced resonance is generated. The generated vortex-induced resonance is transmitted to the water surface through the damping interface between the air and water media, overcoming the hydraulic constraints of the water surface to generate vibration, thereby preventing the surface of the open water conveyance canal 1 from freezing.

[0051] The principle behind the formation of Kármán vortex-type vibration in this invention is as follows: When transverse wind passes around a non-streamlined object (cylindrical pole), paired, alternating anti-symmetrical vortices with opposite rotation directions are generated on both sides of the wake of the cylindrical pole, i.e., Kármán vortex streets. For a cylindrical hollow pole structure, the leeward vortex form and crosswind vibration state are closely related to the Reynolds number of the incoming flow. When the Reynolds number Re < 3.0 × 10⁻⁶... 5 When Re ≥ 3.0 × 10⁻⁶, subcritical aerobatic vibrations will occur; when Re ≥ 3.0 × 10⁻⁶, these vibrations will occur. 6 Transcritical strong wind resonance occurs frequently. Schematic diagrams of the wake structures of fluids at different Reynolds numbers bypassing non-streamlined objects are shown below. Figure 1 As shown.

[0052] Specifically, the main canal of the South-to-North Water Diversion Project is an artificial concrete-lined channel with no overhead cover. The sides of the lined channel are equipped with walkways for operation, inspection, transportation, and maintenance equipment. The walkways are generally made of concrete or asphalt. Buffer protection forest belts are also usually set up on both sides of the walkways for closed management and to ensure water quality safety.

[0053] The length of the cylindrical vertical rod 2 can be set and adjusted according to the deep excavation, high fill channel form and weather conditions such as winter wind force at the channel location to meet the purpose of using natural wind force to transfer vibration to disturb ice in dry channel ice period, prevent ice formation.

[0054] Taking the deep excavation dry channel as an example, the outer diameter of the cylindrical vertical rod 2 is 40mm-50mm, and the length is 3m-4m.

[0055] Preferably, the constraint device 3 comprises a through hole 3-1 arranged on the rod body of the cylindrical vertical rod 2 and arranged radially, a cable 3-2 is inserted into the through hole 3-1, and the cable 3-2 is connected with the through hole 3-1 in interference fit, and the two ends of the cable 3-2 are respectively connected with a pull anchor fixing device 3-3, and the two pull anchor fixing devices 3-3 are located on the opposite banks of the open water conveying dry channel 1, and the cable 3-2 is suspended and pulled up through the two pull anchor fixing devices 3-3 on the opposite banks of the open water conveying dry channel 1, so as to fix the cylindrical vertical rod 2.

[0056] The constraint device 3 is used to maintain the vertical state of the cylindrical vertical rod 2 and anchor in the channel, so as to ensure that the cylindrical vertical rod 2 does not move along the water flow; in addition, the constraint device 3 is also used to provide a unique fixed constraint point in the length direction of the cylindrical vertical rod 2, so as to form an upper free unconstrained end in the air and a lower free unconstrained end in the water body.

[0057] Preferably, the through hole 3-1 is a plurality of through holes arranged at unequal distances along the length direction of the cylindrical vertical rod 2, so as to form moments with different magnification. The cable 3-2 is inserted into the plurality of through holes 3-1 arranged at unequal distances, so as to adjust the height of the fixed constraint point, which is used to adjust the damping characteristics and natural frequency of the cylindrical vertical rod 2 according to the wind speed, and form vortex-induced resonance.

[0058] The vortex-induced resonance generation condition in the application is that when the vortex shedding frequency range generated by the Karman vortex type vibration generation overlaps with the vertical rod self-vibration frequency range generated by the vertical rod self-vibration, the generated vortex-induced resonance is transmitted to the water surface through the damping interface of the air-water body two media, overcomes the hydraulic constraint of the water surface to generate vibration, prevents the water surface of the open water conveying dry channel from freezing, effectively prevents the growth of flowing ice and ice flowers on the water surface in various ice period environments and engineering conditions, and achieves the purpose of protecting the water body from freezing, especially for the open water diversion dry channel. When ice period water conveying is prone to freezing, it generally occurs during cold wave or at night, often accompanied by weather conditions such as strong wind and low temperature, and the open dry channel is extremely superior in wind force condition and timing, which can greatly improve the water conveying efficiency of the dry channel.

[0059] The pull anchor fixing device 3-3 is a movable fixing device, which is convenient to arrange on the horse path on both sides of the open water conveying dry channel 1 channel in a movable manner.

[0060] Preferably, the cylindrical vertical rod 2 is a uniform light cavity cylinder, and the top end of the cylinder is a reverse tapered cylinder for receiving more wind power. Preferably, a plurality of wind holes are arranged in the reverse tapered cylinder, the wind hole diameter is 5-10 mm, the number of wind holes is 10-20, which are uniformly distributed, for collecting more wind power when the wind power is small, and forming airflow acceleration in the wind hole. In the embodiment, the effective area for receiving wind power is about 150-350 cm 2 , forming an easy high-frequency vibration structure.

[0061] The whole process of transmitting vibration by wind power in the application does not need external power, is clean and environmentally friendly, has no any influence on water quality, can guarantee the safety of dry channel ice period facilities, and has remarkable social and economic benefits.

[0062] Preferably, the bottom end of the cylindrical vertical rod 2 is wrapped with a self-floating body 4, the self-floating body 4 is submerged in the water body in a vertical posture, and maintains the cylindrical vertical rod 2 in a vertical state all the time. The self-floating body 4 is a sphere or a hemisphere.

[0063] The self-floating body 4 is embedded with a cylindrical lifting seat 4-1, and the lifting seat 4-1 is sleeved at the bottom end of the cylindrical vertical rod 2.

[0064] The cylindrical vertical rod in the application is placed and anchored by using the self-floating body type + cable way according to the width of the channel surface. Since the number and anchoring point height can be flexibly adjusted, and any external power is not needed, the cylindrical vertical rod can be flexibly configured during the ice period operation according to the specific situation and position of the channel. After the ice period ends, the whole set of devices can be retrieved, cleaned outside the channel, packaged and stored, and used in the next ice period.

[0065] The length ratio of the upper free unconstrained end to the lower free unconstrained end is 7:1-9:1, and in the embodiment, 90% of the cylindrical vertical rod 2 is located above the water surface, and 10% is located below the water surface.

[0066] The vortex shedding frequency is calculated by the following formula

[0067] f s =S t ×U / D

[0068] In the formula,

[0069] f s is the vortex shedding frequency, unit Hz,

[0070] S t is the Strouhal number,

[0071] U is the transverse flow wind speed, unit m / s,

[0072] D is the rod diameter, unit m.

[0073] f in this embodiment s is near the range of 30.57 Hz, D is the diameter of the vertical rod, about 3 cm to 10 cm, and the calculation can obtain that U can generate the required vortex-induced resonance in the range of 0.5 m / s to 15.0 m / s of wind speed.

[0074] The natural frequency of the vertical rod is calculated by the following formula

[0075]

[0076] In the formula,

[0077] f0 is the natural frequency, unit Hz,

[0078] K is the stiffness coefficient of the vertical rod,

[0079] m is the mass of the vertical rod, unit kg.

[0080] The water surface width of the Hebei section of the middle line main canal of the South-to-North Water Diversion Project in this embodiment is 50 m, and the cylindrical vertical rods 2 are uniformly distributed with a radius of 1.5 m to 5 m. By using the above method and device, vortex-induced resonance generated by natural wind on the water surface can form a continuous hydraulic disturbance, which can effectively prevent the growth of ice and ice flowers on the water surface under ice period environmental conditions, so as to achieve the purpose of protecting the water body from freezing.

[0081] The fixed constraint point is located at a position of 0.4 m to 1.4 m above the water surface, and the specific position is adjusted according to the transverse wind speed. In this embodiment, the fixed constraint point is located at a position of 0.5 m above the water surface.

[0082] The anti-icing method of the open water conveyance main canal of the application utilizes the natural meteorological conditions of the open water conveyance main canal in winter, and uses floating and fixed cylindrical vertical rods to be vertically inserted into the water surface of the open water conveyance main canal, so that the cylindrical vertical rods form a state of a free and unconstrained upper end, a free and unconstrained lower end, and a fixed constraint point at a certain point in the middle. Through vortex-induced resonance generated by transverse wind on the cylindrical vertical rods, a torque for vibration amplification is formed to overcome the hydraulic constraints on the water surface to generate vibration and prevent the water surface from freezing. The anti-icing method does not require external power and is green and ecological, easy to arrange and implement during the ice period, and can be dismantled and recycled after the end of the ice period, and is suitable for various cold regions of water diversion projects during the ice period.

[0083] The above embodiments are the preferred embodiments of the application, but the embodiments of the application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the application shall be equivalent replacement methods, and shall be included in the protection scope of the application.

Claims

1. A method for preventing icing in an open-type water conveyance canal, characterized in that, Includes the following steps: The anti-icing method prevents the surface of the open water conveyance canal (1) from freezing by using an anti-icing device in the open water conveyance canal. The anti-icing device in the open water conveyance canal (1) is distributed in a matrix. The anti-icing device for the open water conveyance canal includes a cylindrical pole (2) that is vertically inserted into the water surface of the open water conveyance canal (1). The lower part of the cylindrical pole (2) is located below the water surface, forming a lower free and unrestrained end in the water. The upper part of the cylindrical pole (2) is located above the water surface, forming an upper free and unrestrained end in the air. The cylindrical pole (2) above the water surface is provided with a height-adjustable fixed constraint point. The fixed constraint point is located between the upper free and unrestrained end and the lower free and unrestrained end. A constraint device (3) for fixing the cylindrical pole (2) is provided at the fixed constraint point. When the lateral wind passes around the upper free and unconstrained end, the leeward side of the upper free and unconstrained end forms a Karman vortex-type vibration, generating a range of vortex shedding frequencies. When the lateral wind blows the upper free and unrestrained end, the upper free and unrestrained end generates the pole's self-vibration under the constraint of the constraint device (3), generating the pole's self-vibration frequency range; When the vortex shedding frequency range overlaps with the natural frequency range, vortex-induced resonance is generated. The generated vortex-induced resonance is transmitted to the water surface through the damping interface between the two media, air and water, and overcomes the hydraulic constraint of the water surface to generate vibration, thereby preventing the open water conveyance canal (1) from freezing.

2. The method for preventing icing in an open-type water conveyance canal according to claim 1, characterized in that: The constraint device (3) includes a through hole (3-1) arranged radially on the cylindrical upright (2) body. A cable (3-2) is inserted into the through hole (3-1) and the cable (3-2) is interference-fitted with the through hole (3-1). An anchor fixing device (3-3) is connected to both ends of the cable (3-2). The two anchor fixing devices (3-3) are located on opposite banks of the open water conveyance canal (1). The cable (3-2) is suspended and pulled up by the two anchor fixing devices (3-3) on opposite banks of the open water conveyance canal (1), thereby fixing the cylindrical upright (2).

3. The method for preventing icing in an open-type water conveyance canal according to claim 2, characterized in that: The perforations (3-1) are multiple perforations arranged at unequal intervals along the length of the cylindrical upright (2), thereby forming torques with different magnification factors.

4. The method for preventing icing in an open-type water conveyance canal according to claim 3, characterized in that: The anchor fixing device (3-3) is a movable fixing device.

5. The method for preventing icing in an open-type water conveyance canal according to claim 1, characterized in that: The cylindrical pole (2) is a lightweight, hollow cylinder with an inverted conical top to withstand more wind force.

6. The method for preventing icing in an open-type water conveyance canal according to claim 5, characterized in that: The bottom end of the cylindrical upright (2) is wrapped with a self-floating body (4), which is submerged in water to keep the cylindrical upright (2) always in a vertical state.

7. The method for preventing icing in an open-type water conveyance canal according to claim 6, characterized in that: The self-floating body (4) has a cylindrical lifting seat (4-1) embedded inside, and the lifting seat (4-1) is sleeved on the bottom end of the cylindrical upright (2).

8. The method for preventing icing in an open-type water conveyance canal according to claim 1, characterized in that: The ratio of the length of the upper free and unconstrained end to the length of the lower free and unconstrained end is 7:1 to 9:

1.

9. The method for preventing icing in an open-type water conveyance canal according to claim 1, characterized in that: The vortex shedding frequency is calculated using the following formula. f s =S t ×(U / D) In the formula, f s The vortex shedding frequency is expressed in Hz. S t For the Storoha number, U represents the transverse inflow velocity, in m / s. D is the diameter of the upright, in meters; The natural frequency of the pole is calculated using the following formula. In the formula, f0 is the natural resonant frequency, in Hz. K is the stiffness coefficient of the upright. m represents the mass of the pole, expressed in kg.

10. The method for preventing icing in an open-type water conveyance canal according to claim 1, characterized in that: The fixed constraint point is located 0.4 to 1.4 meters above the water surface, and the specific location is adjusted according to the lateral wind speed.

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