【摘要】：我國是煤炭消費(fèi)大國,同時(shí)也是煤炭開采大國,煤礦瓦斯災(zāi)害一直是困擾煤礦安全高效開采的主要難題,為解決煤礦工程中瓦斯治理難的問題,課題組在多年實(shí)踐和積累下提出了煤層網(wǎng)格化造縫預(yù)抽瓦斯方法,其主體思路是利用高壓旋噴射流逐層切割煤巖,引發(fā)其裂隙網(wǎng)格化貫通,促使其整體卸壓、增透,對(duì)提高低透氣性煤層的采前預(yù)抽效果極其顯著。作為一種安全、高效的造縫預(yù)抽瓦斯方案,高壓旋噴射流技術(shù)在此領(lǐng)域的作用正方興未艾,然而,其相關(guān)理論研究較為缺乏,特別是在雙壁面受限空間作用的射流湍流特性及射流割縫范圍預(yù)測等方面涉獵較少。此外,已有試驗(yàn)還表明高壓旋噴射流割縫系統(tǒng)工況轉(zhuǎn)換過程中存在顯著的瞬變特性,極易誘發(fā)煤體失穩(wěn)、抱鉆等現(xiàn)象。 針對(duì)于此,本文以對(duì)稱雙壁面受限空間射流為研究對(duì)象,基于CFD和PIV技術(shù)分析了雷諾數(shù)、對(duì)稱雙壁面受限空間寬度以及旋轉(zhuǎn)數(shù)等因素對(duì)其流動(dòng)特性的影響規(guī)律,探討了割縫斷面形貌的形成機(jī)理；實(shí)驗(yàn)研究了高壓旋噴射流割縫系統(tǒng)在工況轉(zhuǎn)換過程中的瞬變特性,分析了噴嘴結(jié)構(gòu)、數(shù)量以及閥芯結(jié)構(gòu)變化對(duì)系統(tǒng)瞬變性能的影響規(guī)律；利用均勻試驗(yàn)方法分析了高壓旋噴射流割縫半徑隨射流壓力、噴嘴直徑以及鉆桿速度的變化規(guī)律,研究了割縫半徑的預(yù)測方法；最后,在平頂山十礦和淮南謝一礦進(jìn)行了現(xiàn)場試驗(yàn),探討了高壓旋噴射流煤層內(nèi)網(wǎng)格化造縫能力和預(yù)防煤與瓦斯突出效果。論文主要取得了以下成果： (1)提出了高壓旋噴射流對(duì)稱雙壁面受限空間的物理模型,確定了雷諾應(yīng)力數(shù)值計(jì)算模型及工況；建立了對(duì)稱雙壁面受限空間實(shí)體模型,并采用PIV測試分析了其流場結(jié)構(gòu)與運(yùn)動(dòng)特征,驗(yàn)證了高壓旋噴射流流動(dòng)數(shù)值模擬方法的可靠性和可信性。 (2)基于雷諾應(yīng)力湍流模型模擬了高壓(高雷諾數(shù))條件下雙壁面受限空間內(nèi)射流壓力(雷諾數(shù))、受限空間寬度和旋轉(zhuǎn)速度(旋轉(zhuǎn)數(shù))對(duì)射流流動(dòng)特性的影響規(guī)律。結(jié)果表明雙壁面受限空間射流具有三個(gè)主體區(qū)域(射流核心段區(qū)域、自由射流段區(qū)域、雙壁面受限段區(qū)域)以及兩個(gè)過渡區(qū)域(從核心段至自由射流段過渡區(qū)域、自由射流段至壁面受限段過渡區(qū)域)；雷諾數(shù)未影響主體區(qū)域射流的流動(dòng)規(guī)律和動(dòng)力學(xué)特性,但對(duì)自由射流至壁面受限段區(qū)域影響頗為顯著,并使其局部產(chǎn)生負(fù)壓；雙壁面受限空間寬度雖會(huì)形成空間上的“遲滯效應(yīng)”,但對(duì)射流流動(dòng)狀態(tài)和流動(dòng)特性影響較�。恍D(zhuǎn)數(shù)促使流動(dòng)形態(tài)和動(dòng)力學(xué)特性分布發(fā)生偏向,且在局部區(qū)域產(chǎn)生漩渦結(jié)構(gòu),但基本未影響射流流態(tài)區(qū)域特征；高壓旋噴射流割縫形成的橢圓盤型形貌可判定為局部負(fù)壓拉應(yīng)力,壁面沖蝕、沖刷作用以及空間“遲滯效應(yīng)”作用的協(xié)同結(jié)果所致。 (3)基于流體過渡過程理論研究了高壓旋噴射流割縫系統(tǒng)的過渡過程特性,建立相應(yīng)的理論模型并對(duì)其有效性進(jìn)行了驗(yàn)證。通過對(duì)高壓旋噴射流割縫系統(tǒng)瞬變特性的分析,優(yōu)化了相關(guān)執(zhí)行部件結(jié)構(gòu)及工作參數(shù),保證了系統(tǒng)施工割縫過程轉(zhuǎn)變的安全性。 (4)根據(jù)雙壁面受限空間射流流動(dòng)特性和煤體破碎規(guī)律,建立了預(yù)測高壓旋噴射流割縫半徑的方法,并采用均勻試驗(yàn)方法進(jìn)行了實(shí)驗(yàn)驗(yàn)證,結(jié)果表明割縫半徑與噴嘴直徑成正比和射流壓力的四分之一次方均成正比。 (5)研制出適用于低透氣性煤層瓦斯治理的高壓旋噴射流割縫增透技術(shù)系統(tǒng)成套裝備,并在平頂山十礦己15-24080煤層中安全實(shí)施。現(xiàn)場試驗(yàn)表明,采用高壓旋噴射流割縫技術(shù)能夠減少鉆孔數(shù)量,縮短施工鉆孔時(shí)間,提高施工效率,相對(duì)于普通鉆孔,割縫鉆孔的瓦斯?jié)舛让黠@增大,且衰減較慢,而流量變化不大,在抽采4個(gè)月內(nèi),割縫瓦斯抽采純量提高了3倍以上。 (6)淮南謝一礦B11b煤層現(xiàn)場試驗(yàn)表明,在割縫后60天內(nèi),割縫鉆孔單孔瓦斯?jié)舛却蟛糠直３衷?0%左右,相對(duì)于未割縫鉆孔,單孔瓦斯?jié)舛人p緩慢。割縫孔瓦斯抽采量同比提高了30%以上,
[Abstract]:China is a big coal consumption country, and it is also a big coal mining country. Coal mine gas disaster is the main problem that plagued coal mine safe and efficient mining. In order to solve the difficult problem of gas management in coal mine, the project group put forward the method of coal seam mesh pre suction gas extraction under many years' practice and accumulation, the main idea of which is to use high pressure spin. The cutting of coal and rock by jet stream causes its crack to be meshed and connected to promote its overall pressure relief and penetration. It is very significant to improve the pre extraction effect of low permeability coal seam. As a safe and efficient seam pre gas extraction scheme, the role of high pressure jet flow technology is in the ascendant, however, its related theoretical research is more important. In particular, the characteristics of the jet turbulence and the prediction of the jet slit range are less involved. In addition, the existing experiments also show that there is a significant transient characteristic in the conversion process of the high pressure jet flow slotting system, which is very easy to induce the instability of the coal body and the drilling.
In this paper, a symmetric double wall confined space jet is used as the research object. Based on CFD and PIV technology, the influence rules of Reynolds number, the limited space width of the symmetrical double wall space and the rotation number on the flow characteristics are analyzed. The formation mechanism of the cross section morphology is discussed, and the experiment is carried out to study the high pressure jet slit system in the work. The influence law of the nozzle structure, quantity and the change of the valve core structure on the transient performance of the system is analyzed. The variation law of the slotting radius with the jet pressure, the diameter of the nozzle and the velocity of the drill rod is analyzed by the uniform test method, and the prediction method of the slotting radius is studied. Finally, the method is used to predict the radius of the slotting. In Pingdingshan ten mine and Xiyi mine in Huainan, the field tests were carried out to discuss the seam building capacity of the internal network of high pressure jet flow and the effect of preventing coal and gas outburst.
(1) a physical model of symmetric double wall confined space with high pressure jet flow is proposed. The numerical model and working condition of Reynolds stress are determined. A symmetric double wall limited space entity model is established. The structure and motion characteristics of the flow field are analyzed by PIV test. The reliability of the numerical simulation method of high pressure jet flow flow is verified and the reliability of the numerical simulation method is verified. Trustworthiness.
(2) based on the Reynolds stress turbulence model, the influence of the jet pressure (Lei Nuoshu) on the confined space within the confined space under the condition of high pressure (high Reynolds number), the limited space width and the rotation velocity (rotation number) on the flow characteristics of the jet. The results show that the two wall confined space ejection has three main regions (the jet core region, free jet). The Reynolds number does not affect the flow law and dynamic characteristics of the jet in the main region, but it has a significant influence on the free jet to the wall limited section, and makes it part of the region, and two transition regions (the transition region from the core to the free jet section, the free jet section to the transition region of the wall limited section). Negative pressure is produced; the limited space width of double wall surface will form a "hysteresis effect" in space, but it has little influence on the flow state and flow characteristics of the jet. The rotation number causes the distribution of flow morphology and dynamics to occur in the deviation, and the vortex structure is produced in the local region, but it does not affect the regional characteristics of the jet flow. The shape of the elliptical disc formed by the jet slit can be determined as the result of the local negative pressure tensile stress, the wall erosion, the scour effect and the synergistic result of the space "hysteresis effect".
(3) based on the theory of fluid transition process, the characteristics of the transition process of the high pressure jet slit system are studied, the corresponding theoretical model is established and its validity is verified. Through the analysis of the transient characteristics of the high pressure swirling jet slit system, the structure and the working parameters of the related components are optimized, and the construction slotting process of the system is ensured. The security of the transformation.
(4) according to the flow characteristics of the confined space jet and the breaking law of the coal body, a method to predict the cutting radius of the high pressure jet flow is established, and the uniform test method is used to verify the experimental results. The results show that the radius of the slotting is proportional to the diameter of the nozzle and the 1/4 square of the jet pressure.
(5) a complete set of equipment for high pressure jet flow seams is developed for the treatment of low permeability coal seam gas, and it is carried out safely in 15-24080 coal seam of Pingdingshan ten mine. The field test shows that the high pressure rotary jet slit technology can reduce the number of drilling holes, shorten the drilling time and improve the construction efficiency. Through drilling, the gas concentration in the slotted hole is obviously increased, and the attenuation is slow, but the flow rate is not changed. In the 4 months of extraction, the pure gas extraction is increased by more than 3 times.
(6) the field test of the B11b coal seam in the Shiyi mine of Huainan shows that the gas concentration of the single hole in the slotted hole is mostly kept around 90% within 60 days after the slotting, and the gas concentration of the single hole is slowly decreased compared with the non slit drilling. The gas extraction capacity of the slotted hole is increased by more than 30% over the same period.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TD712

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