【摘要】 为了研究节能高效的油管表面清洗技术,基于计算流体力学方法,应用Fluent软件建立气液两相射流清洗三维物理模型,模拟研究气液两相射流速度场和压力场特性,分析喷嘴锥度、气体体积分数、喷射速度和喷距等射流参数对清洗效果的影响规律。研究结果表明:当气体体积分数为7.4%、喷嘴喷射速度为265 m/s时,两相射流速度较纯水射流提高14.2%,气泡通过喷嘴瞬时的射流速度较纯水射流提高221%。气液两相射流经过喷嘴速度迅速增大到最大值,并出现"等速核"形状,从等速核逐渐向外扩展,速度逐渐减低。两相射流从喷嘴喷出后,射流压力逐渐降低,压能逐渐转换为动能,在距离壁面约1/7喷距处,压力开始以球形向内逐渐增大,在壁面驻点处达到极大值;随喷嘴收缩段锥度增加,射流最大速度逐渐增大,收缩段锥度为3.5时,等速核最长;随着气体体积分数增加,最大射流速度逐渐增大,气体体积分数大于7.4%时,等速核长度基本不变;随喷射速度增大,流场内最大速度和等速核长度不断增加,射流冲击能量更高;随喷距增大,射流冲击壁面的压力逐渐减小,喷距小于5倍喷嘴直径时,冲击效果较好。气液两相射流比纯水射流的清洗作用面积提高24.7%,清洗效率更高。更多还原

【Abstract】 In order to study the saving and efficient cleaning technology of oil pipe surface, a three-dimensional physical model of gas-liquid two-phase jet cleaning was established with fluent software based on the computational fluid dynamics method. Velocity and pressure characteristics of the flow field with gas-liquid twophase jet were simulated. The influence of jet parameters such as nozzle taper, gas volume fraction, jet velocity and spray distance on cleaning effect was analyzed. The results show that the velocity of gas-liquid two-phase jet is 14.2% higher than that of waterjet when the gas volume fraction is 7.4% and the jet velocity of nozzle is 265 m/s. In particular, the jet velocity can increase by 221% when the bubbles pass through the nozzle. The jet velocity increases rapidly to the maximum value and the shape of "constant velocity core" appears when gas-liquid twophase jet passes through the nozzle. The jet velocity gradually decreases with the increase of distance from constant velocity core. After the two-phase jet is ejected from the nozzle, the jet pressure decreases gradually and pressure energy is gradually converted into kinetic energy. Pressure gradually increases in the form of a sphere at the position of about 1/7 jet distance from the wall. Pressure reaches the maximum at the stagnation point of the wall. With the increase of nozzle contraction section taper, the jet maximum velocity gradually increases. As the taper has the value of 3.5, the length of constant velocity core is the longest. As the gas volume fraction increases,the jet velocity increases gradually. While the gas volume fraction is bigger than 7.4%, the length of constant velocity core remains the same. With the jet velocity increasing, the maximum velocity and the length of constant velocity core increase continuously. Therefore, the impact energy of jet is higher. When spray distance increases,pressure of jet impacting on the wall decreases gradually. The impact effect is better when spray distance is lower than 5 times the nozzle diameter. The cleaning area of gas-liquid two-phase jet is 24.7% higher than that of water jet. Gas-liquid two-phase jet has higher cleaning efficiency.更多还原