發(fā)布時(shí)間：2018-12-16 08:58

【摘要】：撞擊流技術(shù)作為強(qiáng)化混合的重要手段,已在煤氣化、聚合注射成型、細(xì)胞破碎等領(lǐng)域得到成功應(yīng)用。掌握撞擊流流動(dòng)特征及混合機(jī)理,對撞擊流反應(yīng)器的研發(fā)、設(shè)計(jì)及運(yùn)行參數(shù)的優(yōu)化有重要指導(dǎo)意義。本文以撞擊流反應(yīng)器為研究對象,采用粒子圖像測速儀(Particle Image Velocimetry,PIV)等實(shí)驗(yàn)儀器及圖像處理方法對小型撞擊流反應(yīng)器內(nèi)流動(dòng)特征及混合特征進(jìn)行了冷態(tài)實(shí)驗(yàn)研究,考察了激勵(lì)對流動(dòng)及混合的影響。主要內(nèi)容如下：1.采用粒子圖像測速儀和高速攝像儀研究了噴嘴射流Reynolds數(shù)在100～2000范圍內(nèi)撞擊流反應(yīng)器內(nèi)流動(dòng)特性。結(jié)果表明：隨著Reynolds數(shù)增大,撞擊流反應(yīng)器內(nèi)依次出現(xiàn)分離流、偏斜振蕩、軸向振蕩及旋渦脫落模式。其中,當(dāng)Re≈300時(shí),反應(yīng)器內(nèi)流動(dòng)模式由偏斜振蕩轉(zhuǎn)化為軸向振蕩。偏斜振蕩是由射流不穩(wěn)定性與撞擊不穩(wěn)定性共同作用引起,并由撞擊面與反應(yīng)器內(nèi)壁的相互作用維持；而射流入口擾動(dòng)和反應(yīng)器受限邊界條件是產(chǎn)生軸向振蕩的主要原因。2.利用粒子圖像測速儀、高速攝像儀及熱線風(fēng)速儀研究了激勵(lì)作用下撞擊流反應(yīng)器內(nèi)撞擊面的振蕩特性。結(jié)果表明,激勵(lì)作用能夠誘導(dǎo)撞擊面周期性的振蕩,撞擊面振蕩頻率與激勵(lì)頻率基本相等,振幅隨著激勵(lì)頻率的增加而減小。當(dāng)Re≤100時(shí),激勵(lì)作用能夠誘導(dǎo)撞擊面產(chǎn)生不同尺度的旋渦,旋渦的尺度隨激勵(lì)頻率的增加而減小。3.運(yùn)用平面激光誘導(dǎo)熒光技術(shù)考察了激勵(lì)作用對撞擊流反應(yīng)器內(nèi)混合效果的影響。結(jié)果表明,當(dāng)撞擊流反應(yīng)器內(nèi)處于分離流模式時(shí),兩股流體間的混合效果較差；當(dāng)流動(dòng)模式轉(zhuǎn)變?yōu)樽猿终袷帟r(shí),兩股流體間的混合效果顯著提升,說明Reynolds數(shù)是影響流體混合的關(guān)鍵因素。當(dāng)流動(dòng)模式為分離流時(shí),激勵(lì)作用能夠較好地改善流體的混合效果；當(dāng)流動(dòng)模式處于自持振蕩時(shí),激勵(lì)對流體的混合效果影響較小。
[Abstract]:Impinging flow technology, as an important means of enhancing mixing, has been successfully applied in the fields of coal gasification, polymer injection molding, cell breakage and so on. Mastering the characteristics of impinging flow and mixing mechanism is of great significance to the research and development of impinging flow reactor, design and optimization of operation parameters. In this paper, the cold flow characteristics and mixing characteristics in a small impinging flow reactor are studied by using particle image velocimetry (Particle Image Velocimetry,PIV) and image processing methods. The effects of excitation on flow and mixing are investigated. The main contents are as follows: 1. Particle image velocimeter and high speed camera were used to study the flow characteristics of jet Reynolds number in impinging flow reactor in the range of 100,2000. The results show that the separation flow, skew oscillation, axial oscillation and vortex shedding mode appear successively in the impinging flow reactor with the increase of Reynolds number. When Re 鈮，

本文編號：2382098