【摘要】：旋流式噴嘴是常用的霧化噴嘴結(jié)構(gòu)形式,內(nèi)置旋芯裝置是產(chǎn)生旋流的有效結(jié)構(gòu)形式,與其他類型噴嘴相比較,它因結(jié)構(gòu)簡(jiǎn)單、中低壓霧化效果好而被廣泛應(yīng)用于消防,環(huán)保和化工等領(lǐng)域。針對(duì)內(nèi)置旋芯旋流噴嘴,基于先進(jìn)的噴嘴綜合測(cè)試臺(tái)和CFD數(shù)值模擬技術(shù),本文圍繞旋芯噴嘴的結(jié)構(gòu)及流場(chǎng)特性,進(jìn)行了數(shù)值模擬和實(shí)驗(yàn)研究。分析了旋芯噴嘴的結(jié)構(gòu)特點(diǎn)和霧化要求,并對(duì)噴嘴結(jié)構(gòu)參數(shù)進(jìn)行了改進(jìn)設(shè)計(jì);介紹了流體運(yùn)動(dòng)分析的方法及相應(yīng)運(yùn)動(dòng)方程,著重分析了旋流噴嘴內(nèi)部和外部流場(chǎng)運(yùn)動(dòng)狀態(tài),得到噴嘴內(nèi)部速度、壓力分布特性和噴嘴外部霧滴運(yùn)動(dòng)方程,理論分析了流場(chǎng)特性和旋流霧化機(jī)理。探討了旋芯噴嘴CFD模擬的一般方法。在相同的速度進(jìn)口和壓力出口條件下,噴嘴模型作相應(yīng)簡(jiǎn)化,旋芯分隔板長(zhǎng)度等同為噴嘴進(jìn)口直徑,旋芯固定在直管段底部,認(rèn)定旋芯整體為壁面,基于六面體結(jié)構(gòu)網(wǎng)格對(duì)三維模型進(jìn)行網(wǎng)格劃分,選用標(biāo)準(zhǔn)k??湍流模型,采用連續(xù)介質(zhì)-水進(jìn)行穩(wěn)態(tài)條件下的數(shù)值模擬。針對(duì)直通噴嘴和旋芯噴嘴,以及旋芯螺旋角、內(nèi)錐角等旋芯結(jié)構(gòu)參數(shù)變化,對(duì)噴嘴流場(chǎng)進(jìn)行了數(shù)值模擬,分別就流場(chǎng)內(nèi)速度、壓力分布進(jìn)行了對(duì)比分析。模擬結(jié)果表明,和普通直通噴嘴比較,旋芯噴嘴出口速度更大、速度分布更均勻,霧化效果更好,噴射距離更遠(yuǎn);旋芯噴嘴出口軸向速度衰減更快,有了明顯的切向速度,霧化錐角更大。由于流體回流和對(duì)空氣的卷吸作用,噴嘴出口位置會(huì)形成一個(gè)空氣錐,流體會(huì)形成膜狀旋轉(zhuǎn)噴出,使旋芯噴嘴顯現(xiàn)空心錐的霧化特性。噴嘴Qg錐角為90°左右時(shí),流體壓損最小、回流相對(duì)較小、速度分布較均勻、軸向速度和切向速度相對(duì)較大,最為優(yōu)化。旋芯螺旋角為15°左右時(shí),噴嘴內(nèi)部流場(chǎng)軸向速度和切向速度相對(duì)較大,壓損較低,最為優(yōu)化�；趪娮炀C合試驗(yàn)臺(tái),就直通噴嘴和內(nèi)置旋芯噴嘴進(jìn)行了對(duì)比實(shí)驗(yàn)研究,完成了流量特性實(shí)驗(yàn)和噴霧分布實(shí)驗(yàn),獲取了流量-壓降關(guān)系曲線、霧化角-壓降關(guān)系曲線和噴霧分布曲線,實(shí)驗(yàn)數(shù)據(jù)較好地驗(yàn)證了理論分析和數(shù)值模擬的結(jié)果。
[Abstract]:Swirl nozzle is a commonly used structure form of atomization nozzle, and the inner core device is an effective structure form for producing swirl flow. Compared with other types of nozzle, it is widely used in fire protection because of its simple structure and good atomization effect at medium and low pressure. Environmental protection and chemical industry. Based on advanced nozzle test bench and CFD numerical simulation technology, the structure and flow field characteristics of core nozzle are studied by numerical simulation and experiment. The structure characteristics and atomization requirements of the swirl nozzle are analyzed, and the structural parameters of the nozzle are improved. The method of fluid motion analysis and the corresponding motion equation are introduced, and the internal and external flow field motion state of the swirl nozzle is emphatically analyzed. The internal velocity and pressure distribution of the nozzle and the equation of droplet motion outside the nozzle are obtained. The characteristics of the flow field and the mechanism of swirl atomization are analyzed theoretically. The general method of CFD simulation of core nozzle is discussed. Under the condition of the same velocity inlet and pressure outlet, the nozzle model is simplified accordingly. The length of the spin-core separator is the same as the inlet diameter of the nozzle, and the rotary core is fixed at the bottom of the straight pipe section. Based on the hexahedron mesh, the 3D model is meshed, and the standard KG is chosen. The turbulent model is numerically simulated under steady state condition with continuous medium-water. The flow field of the nozzle is numerically simulated and the velocity and pressure distribution in the flow field are compared and analyzed according to the change of the structure parameters of the straight through nozzle and the core nozzle as well as the spiral angle and the inner cone angle of the rotary core. The simulation results show that the nozzle outlet velocity is larger, the velocity distribution is more uniform, the atomization effect is better, the injection distance is longer, the axial velocity attenuation is faster and the tangential velocity is obvious. The atomization cone angle is larger. Due to the reflux of the fluid and the entrainment of the air, an air cone will be formed at the outlet of the nozzle, and the fluid will form a membrane rotating jet, which will make the core nozzle show the atomization characteristics of the hollow cone. When the nozzle Qg cone angle is about 90 擄, the fluid pressure loss is minimum, the reflux is relatively small, the velocity distribution is more uniform, and the axial velocity and tangential velocity are relatively large. When the spiral angle of the core is about 15 擄, the axial and tangential velocity of the flow field in the nozzle is relatively large, and the pressure loss is relatively low. Based on the nozzle test bench, the flow characteristic experiment and spray distribution experiment were completed, and the flow-pressure drop curve was obtained. The atomization angle pressure drop relation curve and spray distribution curve are well verified by the experimental data and the results of the theoretical analysis and numerical simulation.
【學(xué)位授予單位】：武漢工程大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TH136

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