【摘要】：給水管網(wǎng)是重要的市政基礎(chǔ)設(shè)施，是給水系統(tǒng)重要的組成部分。經(jīng)過長年運(yùn)行后的管道易產(chǎn)生腐蝕，沿管道內(nèi)壁會逐漸形成不規(guī)則的生長環(huán)，它是給水管道內(nèi)壁由沉淀物、銹蝕物、黏垢及生物膜相互結(jié)合而成的混合體。生長環(huán)不僅會造成水質(zhì)的二次污染而且會使管道過水?dāng)嗝鏈p小，阻力系數(shù)增加，直接影響管道的通水能力和供水壓力。如何有效去除給水管道內(nèi)壁上的生長環(huán)，成為困擾全國各大供水企業(yè)的一大難題，是必須要徹底解決的現(xiàn)實(shí)問題。氣水脈沖管道清洗法是一種操作簡單、適應(yīng)性強(qiáng)、清洗效果較好、對環(huán)境無污染的生長環(huán)去除方法。但是，這種方法的應(yīng)用現(xiàn)在還處在經(jīng)驗(yàn)階段，對其清洗理論和清洗規(guī)律的研究很少。本文利用試驗(yàn)和數(shù)值模擬兩種手段，揭示了氣水脈沖管道清洗過程中兩相流的流動特性規(guī)律，分析了多個因素對管道壁面剪切力的影響。 采用壓力檢測的方法對清洗過程中的壓降進(jìn)行測定，將試驗(yàn)結(jié)果與氣液兩相流均相流模型相結(jié)合，尋求氣水脈沖管道清洗過程的壓降變化規(guī)律。管道中的水流充入高壓氣體時，管道內(nèi)的壓降比不充氣時增大了幾十倍；每個清洗周期，管道內(nèi)的壓降具有相同的變化。通過設(shè)定不同的試驗(yàn)條件，揭示了供氣壓力、供水流量等參數(shù)對管內(nèi)兩相流壓降變化的影響。在供水流量和脈沖頻率一定的情況下，管內(nèi)兩相流壓降與供氣壓力呈線性關(guān)系；在供氣壓力和脈沖頻率一定的情況下，管內(nèi)兩相流壓降與供水流量呈三次多項(xiàng)式關(guān)系。在大量試驗(yàn)基礎(chǔ)上，對清洗過程中氣液兩相流流型及其轉(zhuǎn)換進(jìn)行分析，確定起主要清洗作用的流型為彈狀流。 基于對水平管內(nèi)的氣液兩相流的理論研究，建立了氣水脈沖管道清洗過程的數(shù)學(xué)模型，采用VOF (volume of fluid)方法進(jìn)行CFD數(shù)值模擬，利用試驗(yàn)結(jié)果驗(yàn)證了模型的合理性，，分別分析清洗過程中直管段和彎管段中流型、動壓、湍流強(qiáng)度、壁面切應(yīng)力等流動特性，為氣水脈沖法清除管壁生長環(huán)的研究提供理論依據(jù)。氣液兩相流形成彈狀流的過程中，水平管道內(nèi)管道長度l100D、彎管道內(nèi)l15D時彈單元趨于穩(wěn)定。往管道水流中充入高壓氣體以后，管道內(nèi)的動壓比不充氣時明顯增大，并且隨著充氣時間的延長持續(xù)增大。管道內(nèi)的湍流強(qiáng)度增大，水的紊動情況加劇，壁面剪切力增大，壁面剪切力沿管道長度的變化趨勢與管道內(nèi)氣水兩相流流態(tài)變化相符。 通過數(shù)值模擬的方法計(jì)算不同管徑、管道傾斜度、管內(nèi)腐蝕情況、進(jìn)氣噴嘴尺寸和位置時管內(nèi)流體與管道壁面的剪切力。條件相同的情況下，管徑小于50mm時，管徑的變化對流體與壁面間的剪切力值和沿管道的分布情況影響不大；當(dāng)管徑大于50mm時，管徑對壁面剪切力的影響較大，隨著管徑的增大剪切力呈先增大后減小的趨勢。向下傾斜管道和水平管的壁面剪切力大于向上傾斜管道的值。粗糙管的壁面剪切力大于光滑管。粗糙度較小時，隨著粗糙度的增大，壁面剪切力增大。粗糙度大于0.3cm，隨著粗糙度的增大剪切力變化不大。進(jìn)氣噴嘴位置相同時，尺寸小于0.5D（D為管徑）的進(jìn)氣噴嘴，管道內(nèi)流體與管壁的剪切力較小，進(jìn)氣噴嘴尺寸大于等于0.5D時，進(jìn)氣噴嘴尺寸的改變對壁面剪切力的影響不大。隨著進(jìn)氣時間的增長，進(jìn)氣位置不同的管道內(nèi)上壁面剪切力值相差不大。在大部分管段內(nèi)，進(jìn)氣噴嘴在管道上部的管內(nèi)流體與下壁面剪切力值最小。 研究結(jié)果有助于提高氣水脈沖管道清洗工程的清洗效果，有利于氣水脈沖管道清洗技術(shù)的推廣應(yīng)用，有利于解決給水管網(wǎng)水質(zhì)二次污染問題，降低供水能耗，為保障人民的身體健康、減少能源的消耗、減輕環(huán)境污染提供技術(shù)支持。
[Abstract]:The water supply network is an important municipal infrastructure, which is an important part of the water supply system. the pipeline is easy to generate corrosion after the long-year operation, and an irregular growth ring is gradually formed along the inner wall of the pipeline, and the inner wall of the water supply pipe is a mixture formed by combining the sediment, the rust, the clay and the biological film. The growth ring can not only cause secondary pollution of water quality, but also reduce the cross-section of the pipe, increase the resistance coefficient, and directly influence the water supply capacity and the water supply pressure of the pipeline. How to effectively remove the growth ring on the inner wall of the water supply pipe becomes a difficult problem for the large-scale water supply enterprises in the whole country, and it is a real problem that must be thoroughly solved. The air-water pulse pipeline cleaning method is a method for removing the growth ring with the advantages of simple operation, strong adaptability, good cleaning effect and no pollution to the environment. However, the application of this method is still in the stage of experience, and has little research on its cleaning theory and cleaning rule. In this paper, the flow characteristics of two-phase flow in the process of gas-water pulse pipeline cleaning are revealed by means of experimental and numerical simulation, and the influence of several factors on the shear force of the wall surface is analyzed. The pressure drop in the cleaning process is measured by the method of pressure detection, the test result is combined with the gas-liquid two-phase flow homogeneous flow model, and the pressure drop variation rule of the gas-water pulse pipeline cleaning process is sought. law. When the water in the pipeline is filled into the high-pressure gas, the pressure drop in the pipeline is increased by dozens of times than when it is not inflated; and the pressure drop in the pipeline has the same change per cleaning cycle By setting different test conditions, the variation of pressure drop and pressure drop of two-phase flow in the tube is revealed by the parameters such as air supply pressure and water supply flow. In the event that the water supply flow and the pulse frequency are constant, the pressure drop of the two-phase flow in the pipe is in linear relation with the air supply pressure; in the case of the air supply pressure and the pulse frequency, the two-phase flow pressure drop and the water supply flow rate in the pipe are three times of polynomial on the basis of a large number of experiments, the two-phase flow type and the conversion of the gas liquid in the cleaning process are analyzed, the flow pattern of the main cleaning action is determined to be elastic, Based on the theoretical study of the two-phase flow of the gas liquid in the horizontal tube, the mathematical model of the gas-water pulse pipeline cleaning process is established, and the numerical simulation of the CFD is carried out by the volume of fluid method, and the model is validated by the results of the test. The flow characteristics of the flow type, the dynamic pressure, the turbulence intensity, the wall shear stress and the like in the straight pipe section and the bent pipe section during the cleaning process are analyzed respectively, and the study of the pipe wall growth ring is provided for the air-water pulse method. On the basis of the gas-liquid two-phase flow forming the elastic flow, the length of the pipe in the horizontal pipe is l100D, and the trend of the elastic unit in the curved pipe when the high-pressure gas is filled into the water flow of the pipeline, the dynamic pressure in the pipeline is obviously increased when the pressure in the pipeline is not inflated, and with the extension of the inflation time, The increase of the turbulence intensity in the pipeline, the increase of the turbulent flow of the water, the increase of the shear force of the wall, the change of the wall shear force along the length of the pipe and the flow state of the two-phase flow of the gas in the pipeline in accordance with that method of numerical simulation, the pipe wall and the pipe wall of the pipe are calculate by the method of numerical simulation, the pipe inclination, the corrosion condition in the pipe, the size and the position of the intake nozzle, The shear force of the surface is the same. When the pipe diameter is less than 50mm, the shear force value between the fluid and the wall surface and the distribution of the pipe are not affected by the change of the pipe diameter; when the pipe diameter is larger than 50mm, the influence of the pipe diameter on the shear force of the wall surface is large, The tendency to decrease. The wall shear force of the downward inclined pipe and the horizontal pipe is greater than the upward inclination The value of the inclined pipe. The shear force of the surface of the rough pipe It is larger than the smooth tube. The roughness is small, with the increase of the roughness, the wall surface The shear force is increased. The roughness is greater than 0. 3cm, and the shear force increases with the increase of the roughness. The force change is not large. When the position of the air inlet nozzle is the same, the air inlet nozzle with the size of less than 0.5D (D is the pipe diameter), the shearing force of the fluid in the pipeline and the pipe wall is small, the size of the air inlet nozzle is greater than or equal to 0.5D, and the change of the size of the air inlet nozzle is equal to the shear force of the wall surface. The influence of the air intake time is not large. With the increase of the air intake time, the shear force on the inner wall surface of the pipe with different air intake position The difference between the values is not large. In most of the pipe sections, the intake nozzle is cut from the pipe in the upper part of the pipe with the lower wall The method is beneficial to the popularization and application of the air-water pulse pipeline cleaning technology, is beneficial to solving the problem of secondary pollution of the water quality of the water supply pipe network, reduces the energy consumption of the water supply, and aims to ensure the health of the people, Reduce energy consumption and reduce environmental pollution
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU991.3

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