【摘要】：近年來我國水利水電事業(yè)迅速發(fā)展,新建了許多大型水利水電工程,這些工程往往具有高水頭、大流量的特點(diǎn),泄洪消能問題較為突出,許多地質(zhì)條件差,對環(huán)境要求高的在建和將建工程都放棄了挑流消能方案而選擇底流消能。 基于底流消能的跌坎型消能工是一種能適應(yīng)高水頭、大流量的新型消能工。由于跌坎的存在,水流進(jìn)入消力池后,沿程得到一定程度的擴(kuò)散,主流兩側(cè)形成漩渦以及強(qiáng)烈的紊動剪切擴(kuò)散,將高速的主流引離臨底區(qū)域,臨底流速有效降低,因此基于底流消能的跌坎型底流消能工,具有消能率高、入池流態(tài)穩(wěn)定,對地質(zhì)條件適應(yīng)性強(qiáng)以及水流霧化小等優(yōu)點(diǎn),該消能工具有較好的應(yīng)用前景。由于入射水流與消力池內(nèi)水體形成紊動劇烈的剪切面,導(dǎo)致大量空氣被卷吸入水中形成水氣兩相流,氣泡存在于水流紊流流場中時(shí),原來的紊流結(jié)構(gòu)勢必會發(fā)生變化,氣泡和水流之間的流動形態(tài)將存在明顯的差異,如氣泡跟隨性的強(qiáng)弱決定了水氣兩相之間的流速差,氣泡的存在使得水體膨脹,水深增加,同時(shí)也會增大水流脈動,增加建筑物的瞬時(shí)荷載,另外還會引起水流附加紊動耗散,因而摻氣濃度的大小及其分布規(guī)律必將影響到消力池內(nèi)臨底流速、壓強(qiáng),消力池內(nèi)水深以及消能率等水力因素。對于摻氣水流的研究,無疑能能幫助人們更好的認(rèn)識跌坎型底流消能工中各水力因素間的關(guān)系,對優(yōu)化跌坎型底流消能工體型設(shè)計(jì)有著重要意義。 本文是基于國家自然科學(xué)基金(項(xiàng)目編號：51169008)而立題,采用水力學(xué)試驗(yàn)的方法,測量了入池Froud數(shù)為3.09至5.41時(shí),跌坎型底流消能工在不同流量、跌坎深度以及入射角度下,不同水流結(jié)構(gòu)區(qū)的流速、底板壓強(qiáng)、摻氣濃度值,并通過對比分析得到入池流量、跌坎深度以及入射角度對不同水流結(jié)構(gòu)區(qū)摻氣濃度沿程分布的影響規(guī)律以及水體中氣泡遷移擴(kuò)散的運(yùn)動機(jī)理。
[Abstract]:In recent years, with the rapid development of water conservancy and hydropower industry in China, many large water conservancy and hydropower projects have been built. These projects often have the characteristics of high water head and large discharge, the problem of flood discharge and energy dissipation is prominent, and many geological conditions are poor. Both the construction and the construction project with high environmental requirements have abandoned the energy dissipation scheme and opted for the energy dissipation at the bottom flow. The energy dissipator based on bottom flow is a new type of energy dissipator with high water head and high flow rate. Because of the existence of the fall, the flow into the stilling pool, along the course to a certain extent of diffusion, the formation of vortex on both sides of the mainstream and strong turbulent shear diffusion, leading the high-speed mainstream away from the near bottom area, the near bottom velocity is effectively reduced, Therefore, the energy dissipation tool based on the bottom flow energy dissipation has the advantages of high energy dissipation rate, stable flow state in the pool, strong adaptability to geological conditions and small atomization of water flow, etc. The energy dissipation tool has a good prospect of application. Due to the turbulent shear surface between the incident water flow and the water body in the stilling pool, a large amount of air is swept into the water to form a two-phase water vapor flow. When bubbles exist in the turbulent flow field, the original turbulent structure is bound to change. There will be obvious differences in the flow patterns between the bubbles and the water flow. For example, the velocity difference between the two phases of water and gas is determined by the strength of the bubble's following property. The existence of the bubble causes the water body to expand, the water depth increases, and the flow pulsation is also increased. Increasing the instantaneous load of the building will also cause additional turbulent dissipation of water flow. Therefore, the magnitude of aeration concentration and its distribution law will affect the hydraulic factors such as the near bottom velocity, pressure, water depth and energy dissipation rate in the stilling tank. The study of aerated flow can undoubtedly help people to better understand the relationship between hydraulic factors in the energy dissipators of the floor flow, and it is of great significance to optimize the design of the energy dissipators of the floor flow. This paper is based on the National Natural Science Foundation of China (item No.: 51169008), using the method of hydraulics test, measuring the Froud number of the entering pool from 3.09 to 5.41, and measuring the energy dissipators with different flow, depth and angle of incidence under the condition of different flow, depth and angle of incidence. The velocity of flow, the pressure of bottom plate, the concentration of aeration in different flow structure areas are obtained, and the flow into the tank is obtained by comparison and analysis. The influence of the depth and the incident angle on the distribution of aeration concentration in different flow structures and the movement mechanism of bubble migration and diffusion in water are discussed.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV135.2;TV131.34

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