CN110565524A - Assessment method of air supply and dehumidification system in main cable of suspension bridge - Google Patents
Assessment method of air supply and dehumidification system in main cable of suspension bridge Download PDFInfo
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- CN110565524A CN110565524A CN201910947114.XA CN201910947114A CN110565524A CN 110565524 A CN110565524 A CN 110565524A CN 201910947114 A CN201910947114 A CN 201910947114A CN 110565524 A CN110565524 A CN 110565524A
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- 239000000725 suspension Substances 0.000 title claims abstract description 36
- 238000007791 dehumidification Methods 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 11
- 238000011156 evaluation Methods 0.000 claims abstract description 6
- 238000001035 drying Methods 0.000 claims description 13
- 239000011800 void material Substances 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000009423 ventilation Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D19/00—Structural or constructional details of bridges
- E01D19/16—Suspension cables; Cable clamps for suspension cables ; Pre- or post-stressed cables
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
- F26B21/004—Nozzle assemblies; Air knives; Air distributors; Blow boxes
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/15—Correlation function computation including computation of convolution operations
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- Theoretical Computer Science (AREA)
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- Computational Mathematics (AREA)
- Mathematical Analysis (AREA)
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Abstract
the invention discloses an evaluation method of an air supply and dehumidification system in a main cable of a suspension bridge, wherein the air supply and dehumidification system in the main cable of the suspension bridge comprises an air supply device for conveying dry air and an air supply pipeline provided with a plurality of small air holes, the air supply pipeline is connected to the air supply device and embedded in the main cable of the suspension bridge, a plurality of cable clamps are sleeved outside the main cable, and each cable clamp comprises a common cable clamp and an exhaust cable clamp; and evaluating the air supply and dehumidification system in the main cable of the suspension bridge according to the total resistance loss generated in the flowing process of the dry air in the main cable of the suspension bridge. The method has the advantages that the air supply and dehumidification system in the main cable of the suspension bridge is evaluated according to the total resistance loss generated in the flowing process of the dry air in the main cable of the suspension bridge, so that the structural reasonability of the air supply and dehumidification system in the main cable and the reasonability of air inlet parameter setting are determined, and the result is accurate.
Description
Technical Field
the invention relates to the technical field of suspension bridge cable dehumidification, in particular to an evaluation method of an air supply and dehumidification system in a main cable of a suspension bridge.
Background
the main cable and the sling of the suspension bridge are respectively important load-bearing and force-transmitting components, so the durability of the cable component directly influences the service life of the long-span suspension bridge. In recent years, the detection of a part of main cables and slings of a large-span suspension bridge shows that the corrosion problem of high-strength steel wires in the main cables and slings of the suspension bridge is quite serious, the zinc coating of the part of the high-strength steel wires is corroded completely, the strength of the high-strength steel wires is degraded to different degrees, and the durability problem is quite prominent, which is described in documents such as ' review of anticorrosion and internal temperature and humidity change mechanism of the main cables of the large-span suspension bridge ', latest progress of dehumidification system research of the main cables of the suspension bridge in China ' and the like. Therefore, the method has important engineering value for implementing effective anticorrosion protection on the cable member of the suspension bridge.
The traditional main cable anticorrosion system is to coat an anticorrosion layer on the outside of the main cable to prevent rainwater and wet air from entering the inside of the main cable. The corrosion prevention system delays the corrosion of the high-strength steel wire of the main cable to a certain extent, but cannot fundamentally solve the corrosion problem. Because along with the ageing fracture of anticorrosive coating, inside outside steam can enter into the main push-towing rope from anticorrosive coating crack department, and then corrodes high strength steel wire. In addition, the conventional corrosion-resistant coating scheme cannot remove moisture that enters the interior of the main cable during installation thereof. In recent years, a dehumidification scheme of introducing dry air from the outside of a main cable has been widely used in practical engineering, but the dehumidification by air supply from the outside of the main cable has the defects of large energy consumption of air supply, low dehumidification efficiency, high requirement on air tightness of the main cable, difficulty in pressure feeding dry air to the center of the main cable with a large main cable section and the like. In this engineering context, it is considered to convey dry air from inside the main cable member for dehumidification. The specific scheme is that an air supply pipeline is embedded in the center of a main cable, small ventilation holes are formed in the air supply pipeline, dry air is firstly conveyed into the air supply pipeline through a fan, then is diffused into the main cable through the small ventilation holes, and finally is discharged out of the main cable through an exhaust cable clamp. The dry air takes away the moisture in the main cable in the flowing process so as to achieve the aim of dehumidification. The air supply dehumidification system in the main cable has the advantages of low air supply energy consumption, high dehumidification efficiency, thorough dehumidification of the section of the large-size main cable and the like, but an effective evaluation method is still lacked.
disclosure of Invention
The invention aims to provide an evaluation method of an air supply and dehumidification system in a main cable of a suspension bridge.
The technical scheme for realizing the purpose of the invention is as follows:
an evaluation method of a suspension bridge main cable internal air supply dehumidification system comprises an air supply device for conveying dry air and an air supply pipeline (6) provided with a plurality of small air holes, wherein the air supply pipeline (6) is connected to the air supply device and embedded in the suspension bridge main cable, a plurality of cable clamps are sleeved outside the main cable, and the cable clamps comprise common cable clamps (7) and exhaust cable clamps (8); evaluating an air supply and dehumidification system in a main cable of the suspension bridge according to total resistance loss delta P generated in the flowing process of dry air in the main cable of the suspension bridge; the total resistance loss
ΔP＝ΔPf+ΔPe
In the formula,. DELTA.PfIs the on-way gas resistance loss, delta P, in the main cable of the suspension bridgeeLocal gas resistance loss in a main cable of the suspension bridge;
wherein s is the hole spacing of the air supply pipeline, n is the hole number of the air supply pipeline, d is the hole diameter of the air supply pipeline, epsilon is the leakage rate of the dry air along the main cable, xi is the void ratio of the section of the main cable, and v is the leakage rate of the dry air along the main cable0An initial flow rate of the drying air, ρ is a density of the drying air, λ is an on-way resistance coefficient of the drying air flowing inside the main cable,the local resistance coefficient of the dry air flowing in the main cable;
In the formula, mjNumber of ordinary rope clamps (7) through which the drying air flows, vjis the average flow rate of the drying air.
the method has the advantages that the air supply and dehumidification system in the main cable of the suspension bridge is evaluated according to the total resistance loss generated in the flowing process of the dry air in the main cable of the suspension bridge, so that the structural reasonability of the air supply and dehumidification system in the main cable and the reasonability of air inlet parameter setting are determined, and the result is accurate.
Drawings
fig. 1 is a schematic structural diagram of a gas supply and dehumidification system inside a main cable of a suspension bridge.
Fig. 2 is a schematic diagram of the present invention.
In the figure: 1. the high-pressure fan, 2, a rotary dehumidifier, 3, a static pressure box, 4, a regulating valve, 5, a vortex flowmeter, 6, an air supply pipeline, 7, a common cable clamp, 8, an exhaust cable clamp, 9, an anticorrosive coating, 10, gas flow in a main cable, 11, gas leakage along the way of the main cable, 12, a main cable section, 13, air inlet flow Q, 14, a micro section 1, 15, a micro section 2, 16, a micro section 3, 17, a micro section n-3, 18, a micro section n-2, 19, a micro section n-1, 20 and a micro section n.
Detailed Description
the invention will be further described with reference to the accompanying drawings.
As shown in figure 1, a stainless steel air supply pipeline is embedded in a main cable of a suspension bridge, and small ventilation holes are formed in the pipeline. Dry air is conveyed to the interior of the air conveying pipeline by adopting an air conveying device, the dry air is diffused to the interior of the main cable through the small ventilation holes and exchanges heat and mass with wet air in the main cable to form saturated wet air, and the saturated wet air reaches a certain air pressure and then is discharged from an exhaust cable clamp arranged on the main cable. Through the multiple air inlet and exhaust processes, the dry air gradually takes away the moisture in the main cable, so as to achieve the purposes of dehumidification and humidity reduction.
In the process of air supply and dehumidification inside the main cable, the resistance loss of the air supply and dehumidification system inside the main cable directly influences the effect of the air supply and dehumidification system. For example, the loss of the dry air resistance of the air supply dehumidification system inside the main cable is too large, so as to ensure a certain air supply distance, the air inlet pressure of the air inlet is inevitably increased, and the increase of the air inlet pressure not only increases the air supply energy consumption and the cost of the air supply equipment, but also increases the leakage of the dry air along the main cable, thereby causing extra waste. The design of the main cable inside air-feeding and dehumidifying system in such a configuration is not reasonable. Therefore, the reasonability of the structure of the air supply and dehumidification system in the main cable of the suspension bridge and the reasonability of air inlet parameters can be evaluated by determining the resistance loss magnitude of the dry air, and the air supply device can also be used for the work of air supply equipment model selection and the like.
The principle of the loss of resistance of the drying air is shown in fig. 2. First, the following three assumptions are made: firstly, the flow direction of the dry air in the main cable is from the opening of the air supply pipeline to the exhaust cable clamp; secondly, the dry air is uniformly distributed along the section of the main cable in the process of flowing from the opening of the air supply pipeline to the exhaust cable clamp; leakage rate of the dry air along the main cable is a constant value.
Setting the air inlet flow of an air supply dehumidification system in the main cable as Q; the opening rate of the air supply pipeline is eta, the length of the air supply pipeline is L, the opening distance of the pipeline is S, and the main cable is divided into n-L/S intervals; the diameter of the section of the main cable is D; the on-way resistance coefficient of the gas is lambda and the local resistance coefficient isThe main cable gas leakage rate along the way is epsilon; the void ratio of the section of the main cable is xi; the total area of the internal voids of the main cable is A.
Firstly, calculating the on-way gas resistance loss delta P generated in the flowing process of the dry air between the main cable steel wiresfThe following are:
after the dry air in the air supply pipeline is conveyed to the x meter distance, the gas outflow rate of each opening of the air supply pipeline is as follows:
The area of the main cable section gap is as follows:
the gas flow rate there is then:
in the formula, v0For the initial velocity of the outflow gas in the main cable, the on-way resistance loss of the outflow gas from outflow to discharge is as follows:
The on-way resistance loss of the outlet gas of the 1 st orifice is as follows:
The on-way resistance loss of the 2 nd orifice effluent gas is:
The on-way resistance loss of the gas flowing out of the nth orifice is as follows:
The total on-way drag loss is then:
In the formula, D0The equivalent diameter of the main cable is calculated according to the fluid mechanics formula as follows:
Substituting (9) into (8) yields the total on-way drag loss as:
second, the local air resistance loss Δ P generated when the dry air passes through the cable-clamp region is calculatedjThe following are:
The local resistance loss generated by the flowing of fluid in a pipeline in fluid mechanics is calculated by the formula:
When the gas flowing out from the jth hole on the gas supply pipeline flows to the exhaust cable clamp, the gas flows through mjthe local resistance loss of the gas flowing out from the orifice is as follows:
In the formula: v. ofjThe average velocity, v, during the flow of the gas exiting the jth orificejThe calculation method of (2) is as follows:
the total gas partial resistance loss during the drying air flow is then:
third, the on-way resistance loss delta P in the flowing process of the drying air is superposedfAnd local drag loss Δ PjThe total gas resistance loss calculation formula is obtained as follows:
ΔP＝ΔPf+ΔPe (15)。
Claims (1)
1. an evaluation method of a suspension bridge main cable internal air supply dehumidification system comprises an air supply device for conveying dry air and an air supply pipeline (6) provided with a plurality of small air holes, wherein the air supply pipeline (6) is connected to the air supply device and embedded in the suspension bridge main cable, a plurality of cable clamps are sleeved outside the main cable, and the cable clamps comprise common cable clamps (7) and exhaust cable clamps (8); the method is characterized in that an air supply and dehumidification system in a main cable of the suspension bridge is evaluated according to total resistance loss delta P generated in the process that dry air flows in the main cable of the suspension bridge; the total resistance loss
ΔP＝ΔPf+ΔPe
in the formula,. DELTA.Pfis the on-way gas resistance loss, delta P, in the main cable of the suspension bridgeeLocal gas resistance loss in a main cable of the suspension bridge;
Wherein s is the hole spacing of the air supply pipeline, n is the hole number of the air supply pipeline, d is the hole diameter of the air supply pipeline, epsilon is the leakage rate of the dry air along the main cable, xi is the void ratio of the section of the main cable, and v is the leakage rate of the dry air along the main cable0An initial flow rate of the drying air, ρ is a density of the drying air, λ is an on-way resistance coefficient of the drying air flowing inside the main cable,The local resistance coefficient of the dry air flowing in the main cable;
In the formula, mjnumber of ordinary rope clamps (7) through which the drying air flows, vjIs the average flow rate of the drying air.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910947114.XA CN110565524B (en) | 2019-09-30 | 2019-09-30 | Assessment method for air supply and dehumidification system in main cable of suspension bridge |
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| CN201910947114.XA CN110565524B (en) | 2019-09-30 | 2019-09-30 | Assessment method for air supply and dehumidification system in main cable of suspension bridge |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111827114A (en) * | 2020-08-04 | 2020-10-27 | 北京赛亿科技有限公司 | Cable-stayed bridge inhaul cable dehumidification system utilizing ventilating steel pipe structure |
| CN111945562A (en) * | 2020-08-12 | 2020-11-17 | 郑州大学 | Dehumidification method of main cable of suspension bridge |
| CN113235428A (en) * | 2021-05-21 | 2021-08-10 | 浙江数智交院科技股份有限公司 | Bridge main cable structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1124077A (en) * | 1964-12-04 | 1968-08-21 | Peter Nikolaus Paulus | Improvements in or relating to air mixing apparatus |
| CN201503089U (en) * | 2009-03-06 | 2010-06-09 | 江苏省交通规划设计院有限公司 | Energy-saving dehumidification device for corrosion prevention of main cable of suspension bridge |
| CN203795310U (en) * | 2014-01-08 | 2014-08-27 | 中铁大桥局集团武汉桥梁科学研究院有限公司 | Suspension bridge main cable dehumidification system for taking in and out air through cable clips |
| CN204856239U (en) * | 2015-08-19 | 2015-12-09 | 南京军理科技股份有限公司 | Dehumidification of suspension bridge main push -towing rope is with integration monitoring device |
| CN107354859A (en) * | 2017-07-04 | 2017-11-17 | 镇江蓝舶科技股份有限公司 | A kind of integrated form dehumidification system safeguarded for main rope of suspension bridge |
| CN109140995A (en) * | 2018-08-20 | 2019-01-04 | 江苏中矿大正表面工程技术有限公司 | A kind of main rope of suspension bridge removal moisture drying system and detection device |
-
2019
- 2019-09-30 CN CN201910947114.XA patent/CN110565524B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1124077A (en) * | 1964-12-04 | 1968-08-21 | Peter Nikolaus Paulus | Improvements in or relating to air mixing apparatus |
| CN201503089U (en) * | 2009-03-06 | 2010-06-09 | 江苏省交通规划设计院有限公司 | Energy-saving dehumidification device for corrosion prevention of main cable of suspension bridge |
| CN203795310U (en) * | 2014-01-08 | 2014-08-27 | 中铁大桥局集团武汉桥梁科学研究院有限公司 | Suspension bridge main cable dehumidification system for taking in and out air through cable clips |
| CN204856239U (en) * | 2015-08-19 | 2015-12-09 | 南京军理科技股份有限公司 | Dehumidification of suspension bridge main push -towing rope is with integration monitoring device |
| CN107354859A (en) * | 2017-07-04 | 2017-11-17 | 镇江蓝舶科技股份有限公司 | A kind of integrated form dehumidification system safeguarded for main rope of suspension bridge |
| CN109140995A (en) * | 2018-08-20 | 2019-01-04 | 江苏中矿大正表面工程技术有限公司 | A kind of main rope of suspension bridge removal moisture drying system and detection device |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111827114A (en) * | 2020-08-04 | 2020-10-27 | 北京赛亿科技有限公司 | Cable-stayed bridge inhaul cable dehumidification system utilizing ventilating steel pipe structure |
| CN111945562A (en) * | 2020-08-12 | 2020-11-17 | 郑州大学 | Dehumidification method of main cable of suspension bridge |
| CN111945562B (en) * | 2020-08-12 | 2022-07-01 | 郑州大学 | Dehumidification method of main cable of suspension bridge |
| CN113235428A (en) * | 2021-05-21 | 2021-08-10 | 浙江数智交院科技股份有限公司 | Bridge main cable structure |
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